Questions and interpretations for NACE MR0175/ISO 15156


 

Question 1.

Some of the materials we produce are in thicknesses or diameters that fall outside the scope of MR0175. We request clarification or guidance as to how hardness testing requirements that fall outside the scope of MR0175 should be addressed.

 

QUESTION 2:

MR0175 is obviously written for guidance in meeting the H2S corrosion problem. Where does NACE address chloride corrosion cracking, particularly in pipe and tube materials? We are seeing more and more customer specs calling for special materials. What is the NACE opinion on best pipe/tube materials for defeating chloride corrosion cracking?

 

QUESTION 3:

The "Changes to NACE Standard MR0175-2003" document states the following: "MR0175 is not expected to be technically changed before it is combined with ISO 15156. ISO 15156 is in a different format, with most information provided in tables, so it will not look the same, but it will be technically equivalent." Although this statement says that the two standards will be technically equivalent, their respective sections on applicability show the following deviations:

 

 (a) NACE MR0175 has a generic rule (1.4.1.1) of a H2S partial pressure above 0.0003 MPa abs,
       whereas NACE MR0175/ISO 15156 has no such rule.

 (b) NACE MR0175 has a generic exception rule (1.4.2.1) of a total pressure less than 0.45 MPa abs,
       whereas, within NACE MR0175/ISO 15156, this is only applicable to "Flow-lines, gathering lines,
       field facilities and field processing plants" and "Water-handling equipment." (I assume that you
       are aware that MR0175/ISO 15156 Part 1 (2001) mentions 4.3 bar whereas Parts 2 and 3 (2003) mention 0.45 MPa abs).

 (c) NACE MR0175 has a generic exception rule (1.4.2.2) for multiphase systems under certain conditions,
      whereas NACE MR0175/ISO 15156 has no such rule. Can you please clarify?


 QUESTION 4:

Crude oil storage and handling facilities operating at a total absolute pressure below

0.45 MPa. My understanding of the above paragraph is that, it includes only dead oils with no gas in equilibrium. If any gas is in equilibrium with a crude (operating less than 0.45 MPa) which contains H2S more than 0.3kPa (in the gas phase), the whole system is considered as sour. I need your advice for my understanding, if correct or not?


 QUESTION 5:

Water handling facilities (less than 0.45 MPa) I really don’t know what does it mean? It means that the possibility of corrosion is low enough to be excluded from the standard requirements? Or the consequence of the problem is minimum? Can we conclude from the above paragraph that, low pressure water handling facilities, has no gas to be released which may produce SSC or any hydrogen problems?

 

QUESTION 6:

Is it the intent of NACE MR0175/ISO 15156-2 that material manufacturers state on the Material Test Certificates that material conforms to the NACE standard even though no operating criteria are known?

 

QUESTION 7:

Is a NACE office available in Italy or in other European countries?

QUESTION 8:

With reference to Paragraph 1.10.2: Equipment manufactured with UNS N04400 and operating before the issuing of the last MR0175 edition may be replaced today with equipment manufactured with the same material, if the equipment design and environmental conditions have not been changed? If a conformity declaration to MR0175 is required for the new equipment, which edition must be declared (2003 or previous)?

QUESTION 9:

 

For new wells and/or petroleum plants designed according to MR0175 before its last edition, but manufactured after the last edition was issued, may materials considered by the design but not listed in the new standard edition be used?

 

If a conformity declaration to MR0175 is required for the equipment of the new well/plant, which edition must be declared (2003 or previous)?

 

QUESTION 10:

May materials not listed in the last edition of MR0175, which have successfully passed test requirements of TM0177 and/or have demonstrated adequacy for service performances, have your declaration of conformity and be certified by the manufacturer "in conformity with NACE MR0175-2003"?

QUESTION 11:

I need your help with the definition of CRAs in Part 3 of MR0175/ISO 15156.

 

The "corrosion-resistant alloys" is very general and does not specify whether or not the definition includes the Fe-based alloys or not. More than that, the term CRA is used together with "other alloys" making it even more confusing.

 

QUESTION 12:

Could you please confirm that NACE MR0175/ISO 15156:1: 2001, Paragraph 3.3 contains errors in some copies of the document and should read:

 

3.3

carbon steel

alloy of carbon and iron containing up to 2% carbon and up to 1.65% manganese and residual quantities of other elements, except those intentionally added in specific quantities for de-oxidation (usually silicon and/or aluminum)

 

NOTE: Carbon steels used in the petroleum industry usually contain less than 0.8% carbon.

 

QUESTION 12:

Paragraph 1.8.3.3.1 of the 2003 edition allows "interpolation" between data presented in the tables. If these data are plotted on semi-logarithmic graph paper

such that the ordinate is temperature and abscissa H2S partial pressure, much of the data plots as curves rather than straight lines making "interpolation" problematic lacking the polynomial expression for the curves obtained by a curve-fitting, mathematical routine. Since graphical data are easier to use than the discrete, Cartesian coordinates, I suggest that NACE give the data in the various tables in graphical form, along with the respective polynomial expressions for the resulting curves that enable the user to calculate pH2S for any given temperature.

 

QUESTION 13:

In Paragraph 1.8.3.3.1 it is mentioned that interpolation between H2S levels and temperature is acceptable. When applying this to Table 3 (as an example) what will be the maximum partial H2S pressure at 140°C, where an interpolation is required between 2.8 MPa and unlimited? Does this mean that below 149°C there is no limit to the maximum partial H2S pressure?

 

QUESTION 14:

My customer has some swab tanks that were manufactured in 1953; they are made

of rolled 1/2-inch plate A283C; the tank is 84 in. in diameter and is rated for 100-psi service. The question is given the following conditions does this tank meet NACE MR0175? According to Section A2.1.6 the requirement that all rolled or deformed material must be stress relieved and have a hardness of 22 HRC max. The problem is we cannot or have no documentation as it relates to the heat treat of the plate post welding. yet when tested the material meets the A283C requirements and the hardness are in the 120-127 HB. Ultrasonic testing as part of a corrosion survey on the tank was performed and all was in order. Engineering approval was granted on

the status of the vessel as a pressure vessel under the ABSA (Alberta Boilers Safety Association). This tank is 52 years old, is in excellent condition, and the customer wants to have more current documents on the tank as it relates to its status as an ABSA pressure vessel and it's NACE MR0175.

 

With all this information can a determination be made that this material in its current state is suitable as a material that qualifies as a NACE MR0175/ISO 15156- compliant material? Using the long life, performance, and the mechanical data gathered can this determination be made? If so, can these criteria be used to establish a basis for performing future work on this exact style of tank?

QUESTION 15:

Base Material

 

In accordance to NACE MR0175/ISO 15156, Part 1, Item 7, 3rd paragraph, "no additional laboratory testing of pre-qualified materials selected in these ways is required."

 

In accordance to NACE MR0175/ISO 15156, Part 2, Item B1, letter "a," "Some carbon and low alloy steels described or listed in A.2 might not pass some of laboratory . . ."

 

In our understanding, NACE Standards TM0177 and TM0284 are used to qualify new materials that are not previously included in NACE MR0175. If we are using materials previously included in NACE MR0175, it is not necessary to test them according to NACE TM0177 and TM0284.

 

We would like you to confirm if our interpretation below is correct and if not give us the correct interpretation.

 

QUESTION 16:

image Paragraph 1.10.2 states, ―The user may replace materials in kind for existing wells or for new wells within a given field if the design basis for the equipment has not changed.‖

Does this statement include valves or valve components that are used within wells?

 

QUESTION 17:

When materials in an existing field are replaced, what criteria should be used? Paragraph 8.2 of ISO 15156-1 provides some criteria for qualification, but it is not clear what approach should be used for materials that have been in use with no problems, but documentation does not exist.

 

QUESTION 18:

I need some clarifications on the clause 8.2 of the MR0175/ISO 15156-1 (Qualification based upon field experience).

 

―A material may be qualified by documented field experience‖--‖the duration of the documented field experience shall be at least two years. . . ―

 

What kind of documentation is expected? We need to know exactly what to ask from the end user. Is a letter describing the conditions for which the material qualified for the past two years enough?

 

QUESTION 19:

What do we (the equipment manufacturer) do with this documentation? Does it have to be filed with NACE? If yes, is this our responsibility?

 

QUESTION 20:

If filing with NACE is not required, do we have to verify the claims or can we just provide the materials as requested by the end user?

 

QUESTION 21:

In the pre-December 2003 MR0175, Paragraph 1.10 (The Effect of Changing Requirements in MR0175 on Existing Equipment) spelled out how to handle materials that MR0175 made changes to. Where is such a statement or treatment in the December 2003 MR0175/ISO 15156?

 

If it was left out, is there a way of handling those changes?

 

QUESTION 22:

Definition of pressure-containing parts on page 7. ―Those parts whose failure to function as intended would result in a release of retained fluid to the atmosphere. Examples are valve bodies, bonnets, and stems.‖

 

Are stems always defined as pressure-containing parts, regardless of features that by design keep the stem intact?

Example #1: Internal entry stems for ball valves that have a shoulder that rests against the body around the stem bore.

Example #2: Shafts for butterfly valves that have a retaining ring holding the shaft inside the valve.

 

QUESTION 23:

Sub-clause 7.1.2 says SSC Resistant Steels for partial pressures equal to or above

0.3 kPa (0.05 psi) can be selected using A.2.

 (a) If criteria, like temperature, hardness are met, do we assume that for all partial pressures above 0.05 psi the suggested SSC-resistant materials could be used? E.g., SSC-resistant materials mentioned in Table A.2 and Table A.3.

 

(b) What are the acceptable pH and Cl- limits?

 

(c) Does A.2.2.3.3 cover L80 type 1?

 

(d) For low-alloy steels described in Section A.2 of this standard, what are the cases where injection of corrosion inhibitors are required, both for downhole casings/tubing and surface pipelines?

 

QUESTION 24:

I was wondering if you could assist me in interpreting the partial pressure limitation for Carbon Steels referenced in part 2 section 7.1.2 and A.2.

 

Is there a partial pressure max limit for carbon steels? If so, where is the reference in MR0175?

QUESTION 25:

There is the sentence in the note 1 of Figure 1 in ISO 15156-2: "The discontinuities in the figure below 0.3 kPa (0.05 psi) and above 1 MPa (150 psi) partial pressure H2S reflect uncertainty with respect to the measurement of H2S partial pressure (low H2S) and steels performance outside these limits (both lower and higher H2S)." I understand the above sentence, and if I will use the carbon steel and low-alloy steel in the sour service above 1 MPa (150 psi) of partial pressure of H2S, what can I do? Should I require a special laboratory test imitating the H2S partial pressure and pH in the service for SSC of the carbon steel and low-alloy steel? Which solution can I use in the special laboratory test?

 

NACE TM0177 A solution or the imitating solution in the service?

 

QUESTION 26:

Does the MR0175/ISO 15156-2, 7.3.2 also apply to low-alloy martensitic steels such as CA6NM which is in fact considered a CRA (MR0175/ISO 15156-3)?

 

QUESTION 27:

Seal welding of vent holes on saddle plates welded to pipe. We have provided vent holes on saddle plates in accordance with ASME B31.3. We have used these saddle plates at support locations as a protective shield to pipe. Now we would like

to close the vent hole by seal welding after completion of saddle welding with pipe and carrying out PWHT. Permanent closing of vent hole is required to avoid corrosion in offshore conditions. Service is crude oil with H2S, i.e., NACE MR0175 is applicable.

 

Kindly advise us about the acceptance of seal welding for these service conditions.

 

QUESTION 28:

Ref Part 2 Figure 2 Butt Weld Survey method for Vickers Hardness Measurement. Location points 17, 18 & 19. What is the acceptance criteria? Table A.1 only provides acceptance for the Weld Cap and Root. As the area is not exposed should the acceptance level be 275 HV 10?

 

QUESTION 29:

Is it acceptable to use HV 500g (microhardness) testing for NACE applications for WPS qualification? I understand that Paragraph 7.3.3.2 of NACE MR0175/ISO 15156 Part 2 says that hardness testing shall normally be carried out using HV 10kg or HV 5kg, which is our usual practice.

 

FYI, the hardness testing was done with HV 500g on CSA Z245.1 Grade 359 pipe material.

 

QUESTION 30:

Per 7.3.3.3 as modified in NACE / ISO 15156-2:2003/Cor.1:2005(E), "Using the Vickers or Rockwell 15N measurement methods, hardness impressions 2, 6, and 10 should be entirely within the heat-affected zone and located as close as possible to, but no more than 1mm from, the fusion boundary between the weld overlay and HAZ."

 

Is a correct interpretation that when welding dissimilar metals such as corrosion resistant overlays on low alloy steels, the phrase, "as close as possible to, but no more than 1mm from, the fusion boundary" means that the indentation should be no less than 3x the mean diagonal length of the indentation from the fusion boundary as is required for adjacent indentations in ISO 6507-1:1998?

 

Note: ISO 6507-1:1998 is referenced by NACE/ISO 15156-2:2003 in the first paragraph of Section 7.3.3.2 (Hardness testing methods for welding procedure qualification).

 

QUESTION 31:

About welds, in accordance with NACE MR0175/ISO 15156, Part 2, Item 7.3.3.4, "hardness acceptance criteria for welds," "weld hardness acceptance criteria for steels selected using option 1 (see 7.1) shall be as specified in A.2.1.4. Alternative weld hardness acceptance criteria may be established from successful SSC testing of welded samples. SSC testing shall be in accordance with Annex B."

 

So, in our understanding, if our welding procedure qualifications (WPSs) are qualified in accordance with NACE MR0175/ISO 15156, Part 2, Item A.2.1.4, it is not necessary to test them according to TM0177.

We would like you to confirm whether our interpretation below is correct and if not give us the correct interpretation.

 

QUESTION 32:

NACE MR0175 and NACE TM0177--WELDS

On the other hand, if we make the test in accordance with NACE TM0177 in our WPSs that are previously qualified to conform to NACE MR0175, what kind of results will we have? Will we have a necessary or redundant results?

 

QUESTION 33:

We are trying to interpret the NACE requirements for pressure vessel plate material. The NACE standard leaves the option of HIC testing with the client, as it appears. In accordance with the standard, the condition in which the HIC testing becomes mandatory should be based on some criteria other than H2S partial pressure. We would appreciate it if you can guide in giving the other conditions if sulfur and phosphorous content are controlled in accordance with NACE. Does HIC become mandatory due to non-uniformity of sulfur and phosphorous in the material due to steelmaking process even if the limit of these elements are maintained?

 

QUESTION 34:

Are there other reasons such as chloride environment?

 

 

QUESTION 35:

According to NACE MR0175/ISO 15156, Part 2, Paragraph 8, HIC test is not mandatory for carbon steel SMLS pipe. But what about maximum sulfur content? Do we have to apply maximum sulfur content requirement to carbon steel regardless of HIC test?

 

QUESTIONS 36:

It appears that ISO 15156-2 is ambiguous in defining the acceptance criteria for HIC testing. Section B.5 and Table B.3 refer to NACE TM0284. This TM prescribes CLR, CTR, and CSR results to be reported for each of the three sections taken from a specimen and also as the average per specimen.

 

(a). Could you please confirm that the intention of Section B.5 and Table B.3 is that the requirements of NACE TM0284 for the evaluation of test specimens should be followed and that CLR, CTR, and CSR should be calculated and reported for each section and the average for each test specimen.

 

Table B.3 does not specify if the criteria apply to the single section numbers or to the averages per specimen or to the averages over a series of specimens. The last of these was suggested recently to us, for qualification purposes, by a materials manufacturer.

 

ISO 3183-3 (the successor to API 5L) uses the same CLR, CTR, and CSR values as criteria as ISO 15156 but in addition it mentions that averages per specimen should be measured against the acceptance criteria (not single section numbers). I think it is common practice to apply this approach.

 

If one decides that the acceptance criteria are to be applied to single sections, I do not believe that using, in addition, the same criteria for the average per specimen yields any useful additional information (because it is less restrictive), but it does no harm either.

 

If, however, one decides that the acceptance criteria are to be applied only to the average per specimen, I am of the opinion that an additional condition should be imposed for single section results or for single crack lengths, for instance, no single crack length should exceed 5 mm, as part of the overall acceptance requirements.

 

(b) Are the acceptance criteria intended to apply to the test results of both single section and the average per specimen?

 

(c) Is the intention that, in coming to a qualification the CLR, CTR, and CSR values be calculated by averaging the results for a series of specimens?

 

(d) If they are intended to apply to only the average per specimen, what additional requirements should be placed on the results of single section results?

 

QUESTION 37:

ISO 15156 / NACE MR0175 does not mention clearly about sulfur restrictions for carbon steel forgings and castings to ASTM-A105 and ASTM-A216 respectively.

 

These two specs are work-horse of any oil/gas processing industry. Almost 75% to 90% of materials of construction would fall into these specifications. For example: flanges and fittings and valves and rotating machinery casings.

 

The paragraph A.2.1.3 states:

 

A.2.1.3 Carbon steels acceptable with revised or additional restrictions

 

In addition to the restrictions of A.2.1.2, some carbon steels are acceptable subject to the revised or additional restrictions as follows.

 

a) Forgings produced in accordance with ASTM A 105 are acceptable if the hardness does not exceed 187 HBW.

 

Please note: In the original standards ASTM-A105 allows sulfur up to 0.040% and ASTM A 216 allows sulfur up to 0.045%. However, NACE MR0175/ISO 15156, Section 8 says: Conventional forgings with sulfur levels less than 0.025 %, and castings, are not normally considered sensitive to HIC or SOHIC.


The above statement means ASTM A 105 forgings are acceptable, if sulfur is limited to 0.025% and hardness to 187 HBW

 

Castings have no additional sulfur limit other than specified in the base spec. (for example: 0.045% for ASTM-A216).

 

The document has reference to many casting and forging grades, but, these two grades are not adequately covered. ASTM A 216 is not covered at all.

 

It would be appreciated if NACE clearly makes mention of these two important materials with limitations if any clearly stated. Would such changes be possible?

(MP INQUIRY #2007-05)

QUESTION 38:

 

Could you please define the word "Qualification."

 

In our understanding, qualification is required for new materials that are not listed in Table A.2 of NACE MR0175/ISO 15156-2. We would like you to confirm that our interpretation is correct and if not what is your position?

 

 QUESTION 39:

 

Paragraph A.2.1.2 on page 17 still shows hot-rolled yet Paragraph A.2.1.3 states that ASTM A 234 grade WPB is an acceptable material. My question is as follows:

 

(a) Does NACE MR0175/ISO 15156-2 allow the use of material ASTM A 234 grade WPB with a heat treatment as shown in ASTM A 234/A 234M-02 Section 7 Heat treatment, subsection 7.2.1, although this type of forming and cooling in still air is not listed in Paragraph A.2.1.2 of the NACE standard?

 

(b) Does the term ―hot rolled‖ referred to in Paragraph A.2.1.2 only apply to sheet or plate material and as such cannot be applied to the forming of butt weld fittings?

 

QUESTION 40:

 

Often my company is asked by customers to certify our forgings to NACE MR0175. It is my understanding from them that our competition (including imports), certifies to MR0175 without normalizing and consequently we are pressured to do the same.

We have three presses, two are fed by gas-fired furnaces, and one is with induction heaters. The gas heat forgings are typically heated to 2,300 to 2,350°F and forged on a 900T or 3500T open die press in a tooling pot, then still air cooled to ambient. The forgings heated by induction are heated to similar temperatures but only a portion of a bar and the flange end is forged close to shape, then air cooled in still air.

 

Customers can order these forgings in the "as forged" or "normalized" condition per SA105. My question is do we have to normalize the forgings coming from either forging process in order to certify to NACE MR0175? The problem is interpretation of NACE MR0175/ISO 15156-2:2003(E), page 17, Annex A, Paragraph A.2.1.2. The heat-treated condition "hot-rolled" is not clearly understood and competitors with similar processes interpret that if the entire raw material piece prior to forge, let's call it a mult, is taken to 2,300 to 2,350°F prior to forge that this satisfies the "hot-rolled" definition.

 

We have contended that our products need to be subsequently followed with a normalizing cycle after being fully cooled to ambient in order to be certified to NACE and that neither of the forging processes listed above satisfies the definition of "hot- rolled" process.

 

 

 QUESTION 41:

 

We require a determination on the acceptability of products manufactured out of

materials meeting ASTM A 234 Gr WPB, ASTM A 420 Gr WPL6, ASTM A 350 Gr LF2, and API 5CT J55, K55, N80, and L80 materials.

 

Alberta Oil Tool manufactures Swage Nipples and Bull Plugs primarily for use in the oil and gas industry. Swage Nipples and Bull Plugs are manufactured from line pipe, tubing, and casing. Line pipe swage nipples and bull plugs are manufactured with materials that meet the requirements of the following specifications:

ASTM A 234/ASME SA 234 Gr. WPB

ASTM A 350/ASME SA 350 Gr. LF2

ASTM A 420/ASME SA 420 Gr. WPL6

 

Tubing and casing swage nipples and bull plugs available in materials meeting API 5CT Grades J55, K55, N80, and L80.

 

Our initial determination is that these products fall into the scope of Section 11. Paragraph 11.5, Pipe Fittings, states that fittings meeting the requirements of ASTM A 234 Grade WPB and ASTM A 105 are acceptable. However, we can find no criteria for pipe fittings that are to be used in low-temperature service applications. In comparison to ASTM A 350 Gr. LF 2 (a low-temperature specification), ASTM A 105 is congruent and therefore we determined that fittings manufactured to ASTM A 350 Gr. LF2 are acceptable under NACE MR0275-2003.

 

Table D2, Acceptable API and ASTM Specifications for Tubular Goods, lists API 5CT Grades J55, K55, and L80 as acceptable materials for tubing and casing, as well as ASTM A 106 Gr. B and ASTM A 333 Gr. 6 materials for pipe. This table lists many of the materials in question. ASTM A 106, GR. B material is used to manufacture fittings that comply with ASTM A 234 Gr. B material is used to manufacture fittings that comply with ASTM A 234 Gr. WPB, while ASTM A 333 Gr. 6 material is used to manufacture ASTM A 420 Gr. WPB, while ASTM A 333 Gr. 6 material is used to manufacture ASTM A 420 Gr. WPL6 fittings.

 

As NACE Standard MR0175-2003 does not clearly identify all the acceptable materials in one location, our interpretation of the entire standard is that all of the swage nipples and bull plugs that we manufacture are acceptable, and meet the requirements of NACE MR0275-2003.

 

Is this interpretation correct? Please have our findings confirmed by answering the following questions. Please provide reasons for any products that do not comply with NACE MR0175-2003.

 

(1) Are fittings meeting ASTM A 234/ASME SA 234 Grade WPB acceptable for use under the scope of NACE MR0175-2003?

(2) Are fittings meeting ASTM A 420/ASME SA 420 Grade WPL6 acceptable for use under the scope of NACE MR0175-2003?

(3) Are fittings meeting ASTM A 350/ASME SA 350 Grade LF2 acceptable for use under the scope of NACE MR0175-2003?

(4) Are fittings manufactured from API 5CT Grade J55 material acceptable for use u under the scope of NACE MR0175-2003?

(5) Are fittings manufactured from API 5CT Grade K55 material acceptable for use under the scope of NACE MR0175-2003?

(6) Are fittings manufactured from API 5CT Grade N80 material acceptable for use under the scope of NACE MR0175-2003?

(7) Are fittings manufactured from API 5CT Grade L80 material acceptable for use under the scope of NACE MR0175-2003?

 

QUESTION 42:

Per A.2.1.4 as modified in NACE / ISO 15156-2:2003/Cor.1:2005(E), "Tubular products with an SMYS not exceeding 360 MPa (52ksi) and listed in Table A.2 are acceptable in the as-welded condition. For these products, hardness testing of welding procedures may be waived if agreed by the equipment user".

 

Is a correct interpretation that all hardness testing is being waived for tubular products with an SMYS not exceeding 52ksi in the as-welded condition if as agreed by the equipment user?

 

 QUESTION 43:

 

We have weld overlays (Inconel 625 filler metal with SAW process) applied to low- alloy ferritic steel valves (ASME/ASTM A 352 Gr LCC). The steel valve is used on wet gas wellhead production platform with operating temperatures at 93°C, operating pressure of 145 bar with vapor fraction of H2S (177 kg-mol/h) and CO2 (877 kg- mol/h). Hardness tests were performed on the as-welded condition. The results achieved were well below the 250 HV criteria of Table A.1 of NACE MR0175/ISO 15156-2 first edition. Since the hardness results complied with the requirements of Table A.1 of NACE MR0175/ISO 15156-2, we believe and understand that the valve does not require postweld heat treatment after the weld overlay. Having met the hardness criteria after overlay we believe that we met the requirements of the following paragraphs of NACE MR0175/ISO 15156-2 first edition:

 

-Paragraph A.2.1.5

-Paragraph A.2.1.4

 

Is our interpretation of Paragraphs A.2.1.5 and A.2.1.4 of NACE MR0175/ISO 15156-2 correct based on the above-stated specific application and conditions and that the valves overlayed with Inconel 625 consumables do not require postweld heat treatment?

 

QUESTION 44:

 

We need a clarification on MR0175/ISO 15156 Part 2:2003, Annex A. We are a manufacturer of temporary pipe work, flowlines, etc., for sour gas service in well testing and process use in a surface application.

 

As such we believe Paragraphs A.2.1 through A.2.4 and Table A.1 with a hardness limit of 22 HRC are applicable in these circumstances.

 

However, pipe suppliers in this region tell us that 26 HRC is acceptable in such applications. I believe the 26 HRC limit is only applicable to material used in a downhole application as in Paragraph A.2.2.3, etc. (i.e., not a surface application) and that this is in error in terms of our usage.

 

QUESTION 45:

In reference to Table D2, Acceptable Specifications for Tubular Goods, in the left column titled ―For All Temperatures,‖ why is Pipe a separate category from Tubing and Casing? In the API 5CT specification (see Paragraph 1.1), as well as the NACE MR0175-2003 standard, ―casing is identical to ―pipe‖ (see Sections 10 and 2, Tubular Components).

 

QUESTION 46:

Are the bolting materials and nuts specified in Paragraphs 6.2.1.2 and 6.2.1.3, respectively, the only acceptable materials in compliance with MR0175-2003 for Exposed Bolting?

 

QUESTION 47:

 

Does Paragraph 6.2.1.1 allow other nuts and bolting materials besides the ones listed in Paragraphs 6.2.1.2 and 6.2.1.3?

 

QUESTION 48:

 

Are the following ASTM bolting materials and nuts acceptable for exposed bolting in accordance with Paragraph 6.2 of MR0175-2003? (ASTM A 193, carbide solution treated, GR B8R, B8RA, B8, B8M; A 194, carbide solution treated, Gr 8R, 8RA; A 320, carbide solution treated, Gr B8, B8M)

 

QUESTION 49:

 

SUBJECT: Paragraph 6.2.1.1 of NACE MR0175-2003 Standard

(a) It is not clear whether or not the word "restrictions" as used in Paragraph 6.2.1.1 of NACE MR0175-2003 includes any environmental restrictions for bolting and nuts exposed to sour gas environments. Are bolting and nuts, which are manufactured from wrought austenitic stainless steel materials in accordance with the applicable paragraph in Section 4 of NACE MR0175-2003, acceptable for use in exposed sour environments with no environmental limits with respect to chloride content, partial pressure of H2S, temperature, and free elemental sulfur?

(b) Is the answer to the above question in agreement with ISO 15156?

 

 

QUESTION 50:

Does NACE MR0175/ISO 15156-2, Paragraph A.2.2.4 apply to Gr. 660 flange bolting materials or only to carbon and low alloy steel bolting materials in Part 2?

 

 

QUESTION 51:

This query is about specifications of external bolting material in NACE MR0175/ISO 15156.

 

In MR0175-2003, Section 6, Paragraph 6.2.1, all external bolting on sour systems that is denied direct atmospheric exposure, due to insulation or flange protectors, is considered to be in sour service because of the chance of exposure to H2S leaks.

 

This seems to be in contradiction with Paragraph 1.4/Appendix A, where a minimum total pressure of 0.45 MPa (4.5 bara) is given as a minimum pressure level for sulfide stress cracking in gas.

External bolting is normally at a lower pressure than that. On the other hand, external bolting may be considered potentially wet, which would lower the limit to a partial pressure of 0.0003 MPa H2S.

 

In NACE MR0175/ISO 15156 Part 2, this specification is maintained for C-steel bolting but it is not extended to CRA bolting in Part 3. I have two questions about this guideline:

 

(a) How should I interpret the ambiguity/exception that exists in regard to minimum pressure level around external bolting?

 

(b) What is the current position of CRA external bolting on sour systems?

 

(c) Is Class 2 bolting accepted or shall it be Class 1?

 

QUESTION 52:

The title of Paragraph A.2.3.2.2 in NACE MR0175/ISO 15156-2 is ―Shear rams.‖ This section allows the use of rams made from quenched and tempered, Cr-Mo, low- alloy steels up to a maximum hardness of 26 HRC provided the composition and heat treatment are carefully controlled and supporting SSC testing is performed. The text of this section does not limit these provisions to just shear rams; however, the section title would imply that only shear rams are covered by its provisions. This apparent shear ram restriction was not in previous revisions to NACE MR0175 (see 12.4.3 in NACE MR0175-2003 for example). It is important to ram manufacturers as well as end users that all Cr-Mo, low-alloy steel rams, not just shear rams, be allowed up to 26 HRC to ensure maximum hang-off capacity and for anti-extrusion purposes. Do the provisions of A.2.3.2.2 apply only to shear rams or can they be applied to other types of rams as well?

 

QUESTION 53:

In NACE MR0175/ISO 15156 Part 2, Paragraph A.2.4, ductile iron ASTM A 536 is listed in Table A.5 as acceptable materials for drillable packer components for sour service. However, it is not mentioned in Paragraph A.2.4.1. Can we use this material for pressure-containing parts, i.e., valve stems?

 

QUESTION 54:

I have a query regarding material suitability on a recent enquiry to supply a nodular iron screw compressor.

 

NACE Standard MR0175 accepts ferritic ductile iron to ASTM A 395. My question is if our existing in-house standard of ASTM A 536 Grade 60/40/18 will comply as a direct alternative. On the face of it tensile strength, elongation are similar at 415N/mm2 and 18%!

 

QUESTION 55:

 

Base Material

In accordance to NACE MR0175/ISO 15156, Part 1, Item 7, 3rd paragraph, "no additional laboratory testing of pre-qualified materials selected in these ways is required."

 

In accordance to NACE MR0175/ISO 15156, Part 2, Item B1, letter "a," "Some carbon and low alloy steels described or listed in A.2 might not pass some of laboratory . . ."

 

In our understanding, NACE Standards TM0177 and TM0284 are used to qualify new materials that are not previously included in NACE MR0175. If we are using materials previously included in NACE MR0175, it is not necessary to test them according to NACE TM0177 and TM0284.

 

We would like you to confirm if our interpretation below is correct and if not give us the correct interpretation.

 

QUESTION 56:

 

We have some questions about some particular points concerning the SSC (NACE Standard TM0177) and HIC (NACE Standard TM0284) tests and the requirements of NACE MR0175/ISO 15156-2003.

 

Our understandings are:

 

SSC tests shall be performed in accordance with NACE Standard TM0177. The solution shall be Solution A given in TM0177 in accordance with requirements given in Table B.1 of NACE MR0175/ISO 15156-Part 2. The duration of the test shall be 720 h in accordance with Paragraph 8.6.7 of TM0177.

 

Test method used shall be in accordance with guideline given in Table B.1 of NACE MNR0175/ISO 15156-Part 2, for severe sour service, i.e., Region 3. UT (Method A) appears to be more adapted to test raw plate and FPB (Method B) to reveal susceptibility to SOHIC and/or SZC that occur at welds, then this latest test appears to be more adapted to test welds.

 

Our questions are:

1) What would you recommend for SSC test methods (refer to TM0177: Method A, B, C, or D) for:

 

-Raw plates

-Weld (to qualify a welding procedure)?

 

In addition, we would like to know which method--A or B--is more contraingnant.

 

QUESTION 57:

For HIC test, NACE MR0175/ISO 15156-2:2003 Table B.3 is not clear regarding the acceptance criteria to be taken into account. We usually understood that "CLR, CTR, CSR" to be taken into account is the average of the values measured from one test specimen as defined in NACE Standard TM0284, Paragraph 4.2.1. What is your position?

QUESTION 58:

NACE MR0175/ISO 15156, Part 2, Annex C, Section C.1 states that "The partial pressure of H2S may be calculated by multiplying the system total pressure by the mole fraction of H2S in the gas." Does the word "may" permit other methods, such as incorporating the effects of non-ideal gas behavior, to calculate partial pressure for determining material selection?

 

QUESTION 59:

I have a request for a clarification for a possible error in Annex D of NACE MR0175/ISO 15156-2 dealing with pH estimation. I've posted it at the ISO Maintenance users' forum, but I had no reply.

 

Annex D (informative) of ISO 15156 Part 2 reports a procedure for in situ pH estimation based on pCO2 + pH2S, T and HCO3-.

 

The maps reported were previously published on EFC 16 (not 17 as quoted) and based, if I'm not wrong, on papers by J.L. Crolet and M. Bonis.

 

However, Figure D.2 is different from the maps published by EFC 16: the pH axis seems shifted some 3/4 of pH unit upward, producing a more neutral pH.

 

I assume the former EFC map is correct and not the ISO. Can somebody confirm my assumption is correct?

 

QUESTION 60:

I need your help with the definition of CRAs in Part 3 of MR0175/ISO 15156.

 

The "corrosion-resistant alloys" is very general and does not specify whether or not the definition includes the Fe-based alloys or not. More than that, the term CRA is used together with "other alloys" making it even more confusing.

 

QUESTION 61:

Paragraph 9.2.4.1 Pressure Containing Components--What is the definition of bonnets? What about drain plugs?

 

QUESTION 62:

 

Our company has understood that NACE Standard MR0175 required the maximum specified hardness for austenitic stainless steels be satisfied at any location on bar stock (e.g., at locations considered significant by the user). Since cold-finished bars frequently have surface hardness values above the maximum specified in MR0175, we have declined to certify these products as compliant to the specification. We appear to be in the minority, or perhaps the only stainless bar producer that interprets the standard in this way. We routinely find competitors' cold-finished stainless bar in the marketplace certified to MR0175 based on a mid-radius hardness even though the surface hardness is above the maximum permitted in the standard.

 

We realize this is a long-standing issue, but would like to clarify the hardness requirements of the MR0175 standard. We understand the logic in requiring the material meet a hardness maximum at any location (e.g., surface) in order to provide a predictable level of stress corrosion cracking resistance. Yet the standard does not clearly state, for example, that meeting surface hardness is a requirement. Please clarify the hardness requirements of MR0175 to allow all stainless bar producers to provide a uniform product to this standard.

 

QUESTION 63:

 

We have some 316 stainless steel housings with a large through bore machined. Inadvertently this bore was machined oversize. We would like to flame spray build up the surface with 316 or 316L stainless material and remachine to size. As we understand the standard, 316 and 316L stainless are both included in a lengthy list of materials accepted for direct exposure to sour gas. As we intend to apply stainless to stainless for the purpose of remachining to dimension and not as a corrosion-inhibiting coating, would this process be acceptable and compliant with the NACE Standard MR0175/ISO 15156?

 

QUESTION 64:

 

For the cast austenitic and duplex stainless steels there is no specific mention of a requirement for post weld heat treatment in Part 3 that discusses welding of these alloys. However, there is a statement in the application of these alloys that they are only acceptable in the solution annealed and quench condition. In my opinion, the as welded condition does not meet the intent of being solution annealed and quenched. So can these alloys be used in the as welded condition?

 

QUESTION 65:

 

Seal welding of vent holes on saddle plates welded to pipe. We have provided vent holes on saddle plates in accordance with ASME B31.3. We have used these saddle plates at support locations as a protective shield to pipe. Now we would like to close the vent hole by seal welding after completion of saddle welding with pipe and carrying out PWHT. Permanent closing of vent hole is required to avoid corrosion in offshore conditions. Service is crude oil with H2S, i.e., NACE MR0175 is applicable.

 

Kindly advise us about the acceptance of seal welding for these service conditions.

QUESTION 66:

 

Per A.6.3 as modified in NACE/ISO 15156-3:2003/Cor.2:2005(E), "The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable."

 

Per Table A.23 note (b) as modified in NACE/ISO 15156-3:2003/Cor.2:2005(E), "Low-carbon, Martensitic stainless steels either cast J91540 (CA6NM) or wrought S42400 or S41500 (F6NM) shall have 23 HRC maximum hardness..."

 

Per 6.2.2.2.2 as modified in NACE/ISO 15156-3:2003/Cor.2:2005(E), "Hardness testing for welding procedure qualification shall be carried out using Vickers HV 10 or HV 5 methods in accordance with ISO 6507-1 or the Rockwell 15N method in accordance with ISO 6508-1. The use of other methods shall require explicit user approval."

 

However, neither a Vickers nor Rockwell 15N acceptance criteria is specified for Martensitic Stainless Steels. Furthermore, ASTM E140 does not provide a hardness conversion for Martensitic Stainless Steels. Thus, there is neither a Vickers nor Rockwell 15N acceptance criteria.

 

Is a correct interpretation that the acceptable hardness test method for qualification of Martensitic Stainless Steels is the Rockwell C Method, regardless of the applied stress, and without the need for explicit user approval?

 

QUESTION 67:

If I want to ballot a new alloy to be used in the acceptable environments described in Table A.32 of NACE MR0175/ISO 15156, which environmental test conditions should be used to qualify for ―Any combination of hydrogen sulfide, chloride concentration, and pH‖ at 135°C (275°F) with elemental sulfur? The same question applies to Table A.34.

 

QUESTION 67:

 

In general, for the tables listed in Annex A of NACE MR0175/ISO 15156, what should the environmental test conditions be to qualify a new alloy where the

―Remarks‖ in the respective tables state ―Any combinations of temperature, partial pressure H2S, chloride concentration, and pH‖?

 

 

QUESTION 68:

 

We have some 316 stainless steel housings with a large through bore machined. Inadvertently this bore was machined oversize. We would like to flame spray build up the surface with 316 or 316L stainless material and remachine to size. As we understand the standard, 316 and 316L stainless are both included in a lengthy list of materials accepted for direct exposure to sour gas. As we intend to apply stainless to stainless for the purpose of remachining to dimension and not as a corrosion-inhibiting coating, would this process be acceptable and compliant with the NACE Standard MR0175/ISO 15156?

 

QUESTION 69:

 

Do Paragraphs 9.2 and 9.5 both apply to choke valves? Additionally, choke valves are also used in applications where they are not directly mounted on the Christmas tree (i.e., manifolds, heaters, separators, etc.); can we still consider the choke valve to fall under Paragraph 9.2 for these applications?

 

QUESTION 70:

 

Paragraph 9.2—Wellheads and Christmas trees. Does this paragraph include the valve bodies that are on the Christmas trees as well as other valve bodies exposed to H2S? In other words, which paragraph in Section 9 refers to the valve body?

(MP INQUIRY #2003-04)

 

QUESTION 71:

 

Paragraph 11.4 of the standard, which is titled "Compressors and Pumps," appears to not address many significant applications for pumps. None of the material classes addressed in Paragraphs 11.4.2, 11.4.3, 11.4.4, 11.4.5, 11.4.6, or 11.4.7 speak to applications in pumps in sour service. Is this intentional? It would appear that the limitations applied to compressors would be also applicable to pumps.

 

QUESTION 72:

Are the bolting materials and nuts specified in Paragraphs 6.2.1.2 and 6.2.1.3, respectively, the only acceptable materials in compliance with MR0175-2003 for Exposed Bolting?

 

QUESTION 73:

 

Does Paragraph 6.2.1.1 allow other nuts and bolting materials besides the ones listed in Paragraphs 6.2.1.2 and 6.2.1.3?

 

  QUESTION 74:

 

With the former MR0175-2000 the material 316L (bar and pipe material) and CF8M (casting material) was allowed for use for NACE applications. With the new revision (MR0175-2003) the 316L does not fulfill the new allowed limits of the chemical components any more and the allowed temperature range to use CF8M is drastically reduced (so that it has nearly no meaning anymore for the NACE applications). According to our experiences these two materials have been very common for applications that require the "NACE conformity."

 

Now we are very interested in the reasons why these two materials are (nearly) not possible with the new specification any more.

 

--Do you know what have been the reasons to change the limits of the allowed alloys and the allowed maximum temperature in this way?

 

--Have there been serious problems with these materials in NACE applications in the past?

 

 

QUESTION 75:

 

Paragraph 4.2—Austenitic Steels (say 316 SS). One of the acceptance limits for these materials is a maximum H2S partial pressure of 15 psia at a maximum of 140°F when no chlorides are present. Can I assume that I can still use a material from this category at a higher temperature than 140°F if the partial pressure of H2S is lower than 15 psia?

 

QUESTION 76:

 

In the past we have used 300 series SS pipes and valves in sour service. We are not sure of the implications and use of SS in sour service according to NACE Standard MR0175-2003. Could you please advise whether 300 series SS (304/316, etc.) can be used at lower H2S partial pressures for temperatures above 60°C (140°F)?

 

 

QUESTION 77:

 

Paragraph 4.2.2 is new. Would you let us know which interpretation applies?

 

  (a) Paragraph 4.2.2 is intended to place a limit on acceptable H2S content under the conditions stated, i.e., when temperature does not exceed 60°C, when no elemental sulfur is present, but without restriction on chlorides.

 

 (b) Paragraph 4.2.2 places a maximum temperature limit of 60°C on the use of austenitic stainless steel under any conditions in which MR0175 applies, for example, at 0.1 psia H2S partial pressure with no chlorides present.

 

QUESTION 78:

 

In addition, please clarify the reason for the 60°C limit in Paragraph 4.2.2:

We have noted that a limit of 60°C is commonly cited with respect to chloride stress corrosion for austenitic SST in other publications, and that chloride is mentioned in Paragraph 4.2.2. Are we correct in assuming, therefore, that the 60°C limit in Paragraph 4.2.2 is based on chloride stress corrosion concerns above 60°C when chloride concentrations above 50 mg/L are present rather than H2S corrosion concerns? That is, the first sentence of Paragraph 4.2.2 does not have a limit on chlorides but does have a temperature limit, whereas the second sentence limits chlorides but does not have a temperature limit.

 

 

QUESTION 79:

 

AISI 316: Technical justification of the temperature limitation to 60°C.

 

 

QUESTION 80:

 

SUBJECT: Paragraph 6.2.1.1 of NACE MR0175-2003 Standard

(a) It is not clear whether or not the word "restrictions" as used in Paragraph 6.2.1.1 of NACE MR0175-2003 includes any environmental restrictions for bolting and nuts exposed to sour gas environments. Are bolting and nuts, which are manufactured from wrought austenitic stainless steel materials in accordance with the applicable paragraph in Section 4 of NACE MR0175-2003, acceptable for use in exposed sour environments with no environmental limits with respect to chloride content, partial pressure of H2S, temperature, and free elemental sulfur?

 

(b) Is the answer to the above question in agreement with ISO 15156?

 

 

QUESTION 81:

 

NACE MR0175/ISO 15156-Part 3: From Table A.2 it seems that AISI 316/316L SS can no longer be used whenever the process temperature is above 60°C even if chlorides are totally absent from the environment. As this could have an enormous impact on the material selection for oil and gas processing plants, I would like to have a confirmation of the above.

 

QUESTION 82:

 

We are now in the detailed engineering design phase of a sour gas refinery, and we have implemented NACE MR0175/ISO 15156 for design purposes. NaCl (sodium chloride) will come to the refinery through three-phase flow pipeline from offshore, after liquid separation in slug catcher; then the sour gas will go to gas treatment units for further processing. Table A.2 refers to chloride content in aqueous solution as mg/L; my question is in sour gas treatment units in which we use austenitic stainless steel, what are the criteria for the limitation of application of austenitic stainless steel? My idea is we have to comply with the first row of Table A.2. There is no means to identify the chloride content in the gas stream.

 

 

QUESTION 83:

 

Would you let me know whether our interpretation is correct? NACE MR0175/ISO 15156-3:2003 Para. A.2.2 states environment limits for austenitic stainless steel. According to Para. A.2.2, austenitic stainless steel (304/316 SS) is applicable with max. H2S partial pressure of 15 psi at a max. temperature of 140°F and UNS S20910 for valve stem is applicable without environmental limit.

 

Austenitic stainless steel (304/316 SS) is applicable to valve stem material at a max. H2S partial pressure of 15 psi and a max. temperature of 140°F. Over a temperature of 140°F, UNS S20910 is applicable material to valve stem.

 

QUESTION 84:

 

I have a technical query related to the latest edition of MR0175/ISO 15156 and the use of 316 stainless steel for sour service application. This latest edition of the standard imposes new restrictions on the use of 316 SS in environments operating above 60°C.

My question is can 316 SS be used above 60°C for non-stressed vessel internals or for items such as thermowells located into sour lines or vessels? I ask this because I note that the standard need not be applied to parts loaded in compression (Part 2, Table 1). The implication may be that parts have to be stressed for SCC to be an issue.

 

As a similar situation to vessel internals and thermowells, please could you advise on the use of 316 stainless steel for valve internals in a sour application, operating above 60°C. Of particular interest is the use of solid 316 SS balls for ball valves.

 

QUESTION 85:

Paragraphs 4.2 and 4.2.1 refer to all CRAs being used in contact with well fluids but do not necessarily include instrument or control tubing (Bourdon tubes) being used in pressure indicators as listed in Paragraph 8.4.4.1. Currently this means that 316 stainless steel alloys (L, Ti, etc.) containing those elements are not ruled out from their being used in gauges where the well fluid wetted parts are not exposed to fluids that do not exceed:

4.2.2 The maximum acceptable H2S partial pressure shall be 100 kPa abs (15 psia) at a maximum temperature of 60°C (140°F), with no restrictions on chlorides, and no elemental sulfur.

 

If the chloride content is less than 50 mg/L, the H2S partial pressure shall be less than 150 kPa abs (50 psia).

 

Each application is subject to the specific environmental conditions to the equipment supplier, particularly if the equipment will be used in sour service.

 

Under the above stated conditions, do gauges that are made with 316 SS alloy steels comply with NACE Standard MR0175-2003?

 

QUESTION 86:

For round bar stock 304/316 SS material, does the NACE MR0175 Rockwell C 22 max hardness requirement refer to the hardness anywhere on the raw material or does it refer to the hardness measured at mid-radius, which is the location where ASTM standards require the hardness measurement to be made?

 

For 304/316 austenitic stainless steel MR0175 indicates that the hardness must be Rockwell C 22 max as long as the material was not hardened to enhance mechanical properties. The hardness on 304/316 SS round bar typically varies with radial position. The material typically has the highest hardness readings at the outer surface and lowest in the center. ASTM standards define hardness measurements for bar stock to be taken at mid-radius. In purchasing raw material, the hardness readings reported are at mid-radius.

 

QUESTION 87:

I would like to have advice regarding the addenda with particular focus on Reference 3.

 

(a) According to Table A.2 of NACE MR0175/ISO 15156-3-2003/Cor. 2-2005 (E), an environmental limit for austenitic stainless steel was added under the title of "Any equipment or components in oil and gas processing and injection facilities after separation."

 

Fluid from the oil wells is processed in the gathering center, which usually consists of flow lines, separators, desalter, storage tanks and gas processing facilities.

 

  (1) What does the "separation" facility mean? Is "separation" the facility downstream from the separator in the gathering center?

  (2) In case that environmental condition of a stream after separation is maximum chloride content above 50 mg/L and max H2S partial pressure below 15 psia, is the austenitic stainless steel acceptable for use?

  (3) If not, is there any technical reason for different environmental limits defined for the facilities before and after separation?

 

(b) According to NACE MR0175/ISO 15156-3-2003/Cor. 2-2005 (E), environmental limits for some materials. Please advise when NACE MR0175/ISO 15156 would be accordingly revised.

 

QUESTION 88:

Paragraph 4.3.1 for UNS S20910 allows this material to be used in sulfur-free environments when the maximum H2S partial pressure is 15 psia to 150°F in the annealed or hot-rolled (hot/cold-worked) condition at 35 HRC maximum hardness.

 

Paragraph 9.4.1 for UNS S20910 allows this material to be used for valve shafts, stems, and pins at a maximum hardness level of 35 HRC in the cold-worked condition, provided this cold working is preceded by a solution-anneal heat treatment.

 

Does this mean that I can use UNS S20910 for valve stems in the cold-worked condition (preceded by a solution-anneal heat treatment) at 35 HRC max with no environmental restrictions?

 

QUESTION 89:

 

We have a client that wishes us to use UNS S17400 double age-hardened stainless steel for the valve stem on some 4.1/16-in. 5k gate valves (basically because we have some in redundant stock and can deliver far quicker than the nickel alloy version of stem we currently use).

 

He does, however, want the valves to comply with API 6A material class DD and the latest version of NACE MR0175. Where there is slight ambiguity is with the use of UNS S17400 for valves and choke components (excluding bodies and bonnets) with an allowable partial pressure of 0.5 psi (ref. Table A.27).

 

Is it correct to assume that this additionally excludes valve stems because these are specifically dealt with in Table A.3, or can valve stems be used manufactured from UNS S17400 (in the required treated condition), as they are a valve component, with an allowable partial pressure of 0.5 psi in accordance with Table A.27?

 

QUESTION 90:

 

SUBJECT: Paragraph 9.4 of NACE MR0175-2003 Standard

(a) Are shafts, stems, and pins used in valves, unloaders, and other devices, when manufactured from austenitic stainless steel materials in accordance with Section 4 of NACE MR0175-2003, acceptable for use in sour environments with no environmental limits with respect to chloride content, partial pressure of H2S, temperature and free elemental sulfur?

(b) If the answer to the former question is no, what are the specific environmental limits?

 

QUESTION 91:

 

SUBJECT: Paragraph 9.4 of NACE MR0175-2003 Standard

(a) Are shafts, stems, and pins manufactured from austenitic stainless steels in accordance with and meet the hardness and heat-treat requirements of Section 4 of MR0175-2003 acceptable for use in sour environments with no environmental limits with respect to chloride content, partial pressure of H2S, temperature and free elemental sulfur?

(b) Is the answer to the above question in agreement with ISO 15156?

 

 

QUESTION 92:

 

SUBJECT: Paragraph 9.3 of NACE MR0175-2003 Standard

The packaging content of large skid-mounted gas compressors applied in the oil and gas, gas processing, and process industries generally include several valves varied in type, such as relief valves, ball valves, globe valves, plug valves, gate valves, butterfly valves, and check valves installed on scrubbers, in process gas piping, and in off-skid mounted header systems and sometimes contain chokes in higher pressure scrubber drain systems. Are the body and bonnet components of valves, when manufactured from austenitic stainless steel materials in accordance with Section 4 of NACE MR0175-2003, acceptable for use in sour environments with no environmental limits with respect to chloride content, partial pressure of H2S, temperature, and free elemental sulfur.

QUESTION 93:

If the answer to the former question is no, what are the specific environmental limits?

 

 

QUESTION 94:

 

Are the non-pressure-containing components of valves, when manufactured from austenitic stainless steel materials in accordance with Section 4 of NACE MR0175-2003, acceptable for use in sour environments with no environmental limits with respect to chloride content, partial pressure of H2S, temperature, and free elemental sulfur?

 

 

QUESTION 95:

 

If the answer to the former question is no, what are the specific environmental limits?

 

 

QUESTION 96:

 

Are the answers to all of the above questions in agreement with ISO 15156?

 

QUESTIONS 97:

 

I have an application where I am supplying a pipeline from a gas compressor to a turbine generator. The pipe is 10 in. in diameter and contains natural gas with H2S.

The H2S concentration is 250 ppm by volume. The gas is pressurized to 475 psi @152°F. I would like to know what table from Annex A this pipe would fall under. The material I would like to use is 304L SS, which satisfies the requirements in A.2. I would appreciate any guidance you can provide with this subject.

 

 

QUESTION 98:

 

Recently I have down loaded a NACE MR0175-ISO 15156-3 Technical Circular 1 from your web.

According to the revised Table A.2, we can use austenitic stainless steel 316 up to 93 degree C.

I have one simple question whether the following condition is allowed for 316SS according to the NACE MR-0175/ISO 1515 Code.

When the temperature is more than 95 degree C and the chloride content is less than 4,500 ppm, can we use 316SS for facilities?

 

 

QUESTION 99:

I am requesting a clarification of intent for comments included in Tables A.2 and A.6 in Annex A of the 2003 edition.

 

In both of these tables there is a statement "these materials shall also -- -- be in the solution-annealed and quenched . . . . condition."

 

It is my interpretation that this was a requirement for the base material and was not intended for a fabricated part, e.g., a welded compressor housing.

 

We have to complete some fabrications and believe the required heat treatment will cause cracking and distortion of the part--however, a part must meet the requirements of MR0175/ISO 15156.

 

 

QUESTION 100:

 

Part 3 of the standard for austenitic stainless steels requires a solution anneal and quench or thermal stabilization along with no cold-work intended to enhance mechanical properties. I have a 316 st/st (UNS S31600) part that we spec 1/4 hard temper, but still falls under the max hardness requirement of HRC 22. My mechanical engineer tells me 1/4 hard in essence means cold-working the material to increase its properties.

 

My question is: Can we do 1/4 hard if we still meet the hardness requirement? I am looking to comply with Annex A.2 and Tables A.2 & A.6 for this part.

 

QUESTION 101:

 

In the latest NACE MR0175 there are two component categories "Instrument tubing and associated compression fittings,..." and "Diaphragms, pressure measuring devices and pressure seals." To which category does the Bourdon tube belong?

 

 

QUESTION 102:

 

SUBJECT: Paragraph 11.4.7 of NACE MR0175-2003 Standard

QUESTION: It is not clear whether or not the word "restrictions" as used in paragraph 11.4.7 of NACE MR0175-2003 includes any environmental restrictions. Does Paragraph 11.4.7 provide an exemption to all of the environmental restrictions or limits detailed in Paragraph 4.2.2 in cases in which an austenitic stainless steel material has been selected for use in compressors in sour environments?

QUESTION: If the answer to the former question is no, are all of the environmental restrictions detailed in Paragraph 4.2.2 of NACE MR0175-2003 included in the word "restrictions" as used in Paragraph 11.4.7?

 

 

QUESTION 103:

 

As a manufacturer of reciprocating compressors, we supply machines for compressing sour gas sometimes with a H2S partial pressure up to 10 bar. Before NACE Standard MR0175-2003 came into force, compressor components like valves, valve cages as well as packing cups were manufactured out of austenitic stainless steel to prevent corrosion.

 

The 2003 edition of MR0175 now contains many restrictions regarding the use of austenitic SS, limiting the H2S partial pressure and temperature to very low values (see page 9, item 4.2.2). Under these circumstances (max. temperature 60°C) these materials are not any more applicable for the compression part.

 

On the contrary, the use of austenitic SS (UNS S31635/1.4571) acc. EN ISO 15156- 3:2003 is allowed--presumed the required heat treatment has been carried out (see page 19, Table A.6). In order to avoid surface corrosion we furthermore intend to

use austenitic SS. But by doing so we are contradicting the NACE standard requirements--the standard that is mostly quoted by our customers. We ask for clarification on your part.

 

 

QUESTION 104:

 

The way I read Paragraph 4.2, austenitic stainless steels meeting Paragraph 4.2.1 must be solution-annealed and quenched or annealed and thermally stabilized with a maximum hardness of 22 HRC. (1) Am I correct in assuming these materials must be annealed regardless of hardness? (2) If a construction started with materials in this condition, would it be necessary to anneal again following a welding operation?

 

QUESTION 105:

 

In Part 3, Table A.4 it shows S31600 stainless, but not S31603 stainless (316Lss). Also, our equipment is a flowmeter which is not specifically referred to anywhere in the standard, so do I treat it as a fitting? As for the bolt material, ASTM A354/ UNS K04100, I don’t see this material anywhere in any of the 3 parts, but I believe it goes into the Part 3 category. This is where I also need help.

 

QUESTION 106:

My stainless steel sheet material qualifies to Section A.2. I am forming this sheet into tubes and (longitudinally) welding the formed tube without filler metals using an automatic arc welding process (ASTM 249/ASTM 269). After welding the tube is fully annealed per ASTM. My hardness values are all below 22 HRC as required.

  (1) Is my welded and annealed tubing bound to the welding requirements of A.2.3 and 6.2.2?

  (2) After annealing, if I now butt weld two ends of the tubing above using the orbital weld (no filler metal) process (no additional anneal), am I now bound to A.2.3 and 6.2.2?

 

 

QUESTION 107:

 

Inconel 600 (UNS N06600) was an included material in the 2002 revision of MR0175, per section 4.1.4.1. In both the 2003 revision of MR0175 and MR0175/ISO 15156-3:2003, I have not been able to find any references to N06600 or any material category/type that would cover this material. Am I overlooking a reference to this material, or was this material removed from the specification? If it was removed, were their specific reasons that lead to its removal?

 

 

QUESTION 108:

 

In Section of Part 3: Table A.2 (austenitic stainless steel) states:

"These materials shall also

-be in the solution-annealed and quenched, or annealed and thermally stabilized heat-treatment condition,

-be free of cold work intended to enhance their mechanical properties, and

-have a maximum hardness of 22 HRC."

 

Whereas for welding in Section A.2.3 it is stated that:

"The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable."

 

I addition Section 6.2.2.2.2 states that "Hardness testing for welding procedure qualification shall be carried out using Vickers HV 10 or HV 5 methods in accordance with ISO 6507-1 or the Rockwell 15N method in accordance with ISO 6508-1.

 

The use of other methods shall require explicit user approval."

 

(a). Please clarify how the requirement for 22 HRC is interpreted in light of this, i.e., what Vickers (HV 10 or HV 5) or Rockwell (15N) value should be used as a maximum for weld HAZ and weld metal?

 

On an associated point, for solid-solution nickel-based alloys (Section A.4) and duplex stainless steels (Section A.7) there are no hardness requirements for materials in the solution-annealed condition (with the exception of one HIP duplex stainless steel alloy). The relevant sections (A.4.3 and A.7.3) on welding state:

 

"The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable".

 

(b). Please confirm that the interpretation that NACE MR0175/ISO 15156 therefore places no hardness restrictions for welds in these materials is correct.

QUESTION 109:

 

In several paragraphs of both NACE MR0175 and ISO 15156 it is stated that materials (e.g., austenitic SS) are acceptable if they are free of cold work intended to enhance their mechanical properties or is stated "in the annealed or solution- annealed condition only" (e.g., Ni-based only).

 

Is there a limit to what is considered cold work, e.g., 5%, or is any cold work whatsoever included?

 

 

QUESTION 110:

 

In order to decrease the danger of low stress creep we slightly overstress superaustenitic SS and Ni-based alloy valve bodies during hydrotesting. This overstressing causes a "cold deformation" of 0.2-0.5%. We do not use the cold deformation in order to enhance the mechanical properties!

 

Is this practice allowed under the rules of NACE MR0175/ISO 15156 ?

 

QUESTION 111:

We have requirement of 6Mo valves for one of our ongoing projects wherein we need to use A 351 CK3MCuN (J 93254) body material.

 

With reference to Table A -8 of NACE MR0175/ISO-15156 - 2003 Environmental and materials limits for highly alloyed austenitic steels used for any equipment or components ) we have following clarification:

 

Table A - 8 lists the above material J 93254 (ASTM A 351 CK3MCuN) can be used for any combinations of temperature, pH2S, chloride concentration and in situ pH occurring in production environments are acceptable.

 

We understand that forging grade equivalent of above J 93254 which is UNS 31254 will also be qualified under these conditions.

 

Please confirm /clarify the whether forging grade equivalent of J 93254 which is UNS 31254 will also be qualified?

 

QUESTION 112:

We have a question regarding the meaning of a sentence in Paragraph 4.4 in MR0175-2003. This same sentence is repeated in Paragraph 10.2.1.

 

The paragraph states:

Highly alloyed austenitic stainless steels in this category are those with Ni% + 2 Mo% >30 and 2% Mo minimum.

 

A1. Does the statement mean that there are essentially two groups in this category? Such that . . .

 

One qualifying group consists of materials that contain N% + 2 Mo% >30

 

Another qualifying group consists of any austenitic stainless steel with 2% Mo minimum (such as 316, 317).

 

A2. Or does the statement mean that there must be a minimum of 2% Mo in the Ni%

+ 2 Mo% >30 requirement?

 

Since the environmental restrictions in Paragraph 4.4 are the same as in 4.2 (where most austenitics are acceptable), I assume #A1 is the correct interpretation since this would allow for inclusion of 316 and 317.

 

 

QUESTION 113:

 

NACE Standard MR0175-2003 has two different highly alloyed austenitic SS families, one (Paragraph 4.4) with Ni% + 2 Mo% >30 (and Mo>=2%) and one (Paragraph 4.5) with PREN >40. Both have two different ranges for temperature, partial H2S partial pressure, and maximum chloride content. Which environmental limits have to be used for materials applicable for both categories like UNS S31254?

 

 

QUESTION 114:

 

Paragraph 4.4 in MR0175 identifies "Highly Alloyed Austenitic Stainless Steels with Ni% + Mo>30 and 2% Mo minimum" as a category. Is it intended by the standard writers that the two conditions be both present? In other words, is it Ni% + Mo>30 with 2% Mo minimum? Or is the 2% Mo minimum another defined material group in the category? I believe it to be the former as I am not aware of highly alloyed austenitic stainless steels only defined by the term "2% Mo minimum."

 

QUESTION 115:

Alloys 400 (N04400), 600 (N06600), and 800 (N08800) were previously listed in MR0175-94 as acceptable to 35 HRC. The newest revision does not list either 600 or 800 and now appears to place equipment restrictions on alloy 400 (Table A.16). None of these alloys appear to qualify by chemistry under A.4 Solid Solution Nickel Based Alloys (Table A.12, p. 21).

 (a) Does 600 qualify anywhere in NACE MR0175/ISO 15156?

 (b) Does 800 qualify anywhere in NACE MR0175/ISO 15156? Can 800 be qualified under A.2.1 Austenitic Stainless Steels? Some publications refer to 800 as a stainless steel and others as a nickel alloy. ASTM lists it as an Ni-Fe-Cr alloy as did MR0175-94.

 (c) I assume 400 is restricted to only the equipment and conditions listed in Table A.16?

 

QUESTION 116:

 

Are "contained" electrical tubular heating elements manufactured from solution- annealed or annealed UNS N08800 tube (sheath material) acceptable for applications under Paragraph A.4.1 (MR0175/ISO 15156-3)? By "contained" we mean that the heating elements are in a bundle totally enclosed inside a pipe body, shell, or tank.

 

QUESTION 117:

Paragraph 10.5.1.1 (NACE MR0175/ISO 15156-3, Sub-clause A.4, Table A.12)) requires a minimum Ni content of 29.5%, but solution-annealed and cold-worked alloy UNS N08535 (Alloy 2535, classified as a "nonferrous alloy" in MR0175-2002) only contains 29.0% Ni (minimum).

 

Does this mean that Alloy 2535 must be restricted to environments described by Paragraph 10.2.1.1 of MR0175-2003 (NACE MR0175/ISO 15156-3, Sub-clause A.2, Table A.9) that are the same as for austenitic stainless steels like 316?

 

 

QUESTION 118:

 

Alloy G-3 (UNS N06985, classified as a "Nonferrous alloy" in MR0175-2002), a 6% Mo, solution-annealed and cold-worked alloy, may contain as little as 35.9% Ni.

Does this mean that its environmental limits are given in Table 5 of MR0175-2003 instead of Table 6 (NACE MR0175/ISO 15156-3, Sub-clause A.2, Table A.12)?

 

QUESTION 119:

 

Is annealed UNS N06625, Grade 1, per ASTM B443, B444, or B446 (also commonly referenced as stabilized or stabilize annealed) acceptable as a material under Paragraph 4.11.1 of MR0175-2003?

 

Discussion: It clearly was acceptable in the previous version of MR0175; however, Grade 1 material is NOT solution annealed, as appears to be required by Paragraph 4.11.1. Solution-annealed material requires annealing at a temperature above 2,000°F and is identified as Grade 2. This condition is typically reserved for service temperatures in excess of 1,100°F.

 

QUESTION 120:

Paragraph 4.11 of NACE Standard MR0175-2003 does not stipulate a minimum cobalt content. Do solid-solution nickel-based alloy wrought materials complying with either of the two chemical composition alternatives detailed in Paragraph 4.11.1, but with zero percent cobalt, qualify for no environmental limits with respect to partial pressures of H2S in accordance with Paragraph 4.11.2?

 

QUESTION 121:

 

We manufacture a fluid-handling product machined from UNS N06600 in the cold- worked condition with a hardness less than 35 HRC. We have certified that this product meets MR0175 based on Paragraph 4.1.4.1 of MR0175-2002.

  (a) It appears this material is not included in MR0275-2003. Is it acceptable to certify that this material meets MR0175-2003 based on the listing in previous versions?

  (b) If not, is it acceptable to continue to certify meeting MR0175-2002?

 

 

QUESTION 122:

 

Old (2002) Paragraph 4.1.5.1 UNS N06625 HRC >35

New (2003) Paragraph 4.11 and A13: N06625 solution-annealed only: Technical justification?

 

QUESTION 123:

 

I have a query regarding UNS N08825 pipe material in hot finished annealed delivery condition as availability of ASTM B 423 (UNS N08825) material in cold finished annealed condition is scarce but it is generally available in hot finished delivery condition above 8" size.

 

Therefore my query goes as follows:

 

"NACE MR0175/ISO 15156-3:2003(E) does not list UNS No. N08825 in hot finished annealed condition in Table A.12, A.13 and A.14. Table A.12 breaks down solid solution nickel-based alloys into Type-4a, 4b, 4c and 4d depending on Cr, Ni+Co, Mo and Mo+W mass fraction and metallurgical condition. Now my question is whether ASTM B 423 (UNS N08825) pipe in hot finished annealed delivery condition for 8" and 10" pipe shall be acceptable for piping because for type 4a and 4b metallurgical condition does states the requirement of cold-worked or hot worked."

 

 

 QUESTION 124:

 

We believe that Alloy 400, UNS N04400, should be included in both the latest version of MR0175 and the imminent ISO 15156 standard. As outlined in the foreword of MR0175-2003, ―Many of the guidelines and specific requirements in this standard are based on field experience with the materials listed . . . ―

 

We propose that Alloy 400, UNS N04400, be added to Section 8, Special Components, Paragraph 8.4.2, Diaphragms, Pressure-Measuring Devices, and Pressure Seals.

 

 

QUESTION 125:

 

In what paragraph are the requirements for wrought bar in nickel-copper alloy (i.e., UNS N04400 and N04405)? In the 2002 version, these materials were covered in Paragraph 4.1.1.

 

QUESTION 126:

 

We manufacture a fluid-handling product machined from UNS N04400 and N04405 in the cold-worked condition with a hardness less than 35 HRC. We have certified that this product meets MR0175 based on Paragraph 4.1.1.1 of MR0175-2002.

  (a) May we continue to certify that this product meets MR0175-2003, since this material is mentioned in Paragraph 10.6.2.2?

  (b) Is it acceptable to continue to certify meeting MR0175-2002?

 

QUESTION 127:

 

What are the reasons for the exclusion of nickel-copper alloys, e.g., UNS N04400, from the materials listed in Section 4?

 

 

QUESTION 128:

 

NACE Standard MR0175-96, Section 4, includes Paragraph 4.1.1 titled Nickel- Copper Alloys specifically listing UNS N04400 (K-Monel), UNS N04405, and N05500. These CRA metals have been omitted from MR0175-2003 except for brief mention under Section 10 for specific equipment not related to our business. We are a manufacturer of process gauges, some of which are for use in sour gas environments. These metals (especially N04400) have always been used in our (and other manufacturers') gauges for pressure-containing parts having direct exposure to sour gas. Have these materials been omitted for a reason or are they still acceptable?

 

 

QUESTION 129:

 

We manufacture instrumentation and in particular, BOURDON TUBE-type pressure gauges. Due to the manufacturing process, 316 SS tube exceeds the hardness limit in NACE MR0175. The alternative has always been to supply ―MONEL‖ UNS N04400 to comply with NACE MR0175. Paragraph 8.4 would previously have referenced N04400 in Section 4, thus meeting the requirements. We note N04400 is referenced in Section 10 only, specific to downhole equipment. We are holders of your standard NACE MR0175-2003. We have a particular query regarding UNS N04400. The 2003 edition of the standard does not contain in Section 4 (CRAs) a section for nickel-copper alloys (NACE MR0175—ALL PREVIOUS ISSUES), and as UNS N04400 does not fall within the stated parameters within Section 4, can you please clarify: Is UNS N04400 no longer within the scope of MR0175-2003 section 4, or will an amendment be issued to re-include it in Section 4?

 

QUESTION 131:

According to NACE Standard MR0175-2003, 625 material, as a solid-solution nickel-

based alloy, is acceptable only in the solution-annealed condition. This constitutes a major change with respect to previous editions, in which 625 material was accepted up to 35 HRC regardless of the delivery condition. The annealed condition is considered the most suitable condition by most of our customers and we are not aware of problems or failures with material 625 used in this condition for NACE applications. Unless a real problem exists in using annealed 625, we would like to understand whether:

 

(a) The definition of solution annealing given in NACE Standard MR0175-2003 has to be interpreted to exclude 625 material in the annealed condition; or


 (b)
For 625 material, annealing performed in a given temperature range (to be suitably defined, even more narrow than the range from 1,600 to 1,900°F) can be considered a solution-annealing heat treatment as defined in Section 2.

 

  QUESTION 132:

 

Question on Alloy 31 (UNS N08031)

The typical chemical composition of this alloy is: Fe bal, Ni 31, Cr 27, Mo 6.5, Cu 1.2, N 0.20. Based on the individual heat chemistry, the alloy could be either a nickel-based alloy (nickel being the highest element) or high-performance stainless steel in which iron is the highest element.

 

NACE MR0175-2002:

*Alloy 31 appears in Section 4: Nonferrous Metals.

*4.1.3 Nickel-Iron-Molybdenum Alloys Paragraph 4.1.3.14 (provides allowed use and the table of balloted data).

NACE MR0175-2003: The nonferrous section is no longer present in this version.

*Section 4 is now entitled ―Corrosion-Resistant Alloys (CRAs)--All Other Alloys Not Defined As Carbon and Low-Alloy Steels and Cast Irons in Section 3

*Section 4.11 Solid-Solution Nickel-Based Alloys (Category) appears to be the section in which Alloy 31 fits the category of 4.11.1: 19.0% Cr min., 29.5% Ni + Co min., and 2.5% Mo min. No specific mention of alloy 31 is made in this section.

*The balloted table of data for alloy 31 appears in Appendix C: Ballot Submittal Data, Table C7.

It appears that name of this alloy UNS N08031 (alloy 31) began to disappear in this version.

 

I fully understand that this document NACE MR0175-2003 is no longer valid and now has been replaced by NACE MR0175/ISO 15156 First Edition, Part 3.

 

NACE MR0175/ISO 15156 First Edition, 2003-12-15, Part 3 (Comments and Questions)

 

It appears that alloy 31 (UNS N08031) should appear in Section A.4 Solid-solution nickel-based alloys.

 

It would further appear that alloy 31 (UNS N08031) fits the materials type 4c described in Table A.12 as: 19.5% Cr min., 29.5% Ni + Co min., and 2.5% Mo min. Is this the material type/grouping that alloy 31 (UNS N08031) should be grouped with?

 

Table D.4 lists various alloys included in the Section A.4 Solid-solution nickel-based alloys. Alloy 28 (Alloy 28 in reality is not a nickel-based alloy) and 32 are listed in this table. No mention is made of alloy 31 in this table or within the document.

Could 32 be a typo error and should be 31??

 

It appears that alloy 31 (UNS N08031) has completely disappeared from this version.

 

I would appreciate clarification on this point. Alloy 31 (UNS N08031) should be listed in this NACE MR0175/ISO 15156-3 First Edition, 2003-12-15, Part 3 document. If this is an error, how do we get it corrected and if this is not an error how do we get alloy 31 in this document?

 

QUESTION 133:

 

I have a query regarding UNS N08825 pipe material in hot finished annealed delivery condition as availability of ASTM B 423 (UNS N08825) material in cold finished annealed condition is scarce but it is generally available in hot finished delivery condition above 8" size. Therefore my query goes as follows:

 

"NACE MR0175/ISO 15156-3:2003(E) does not list UNS No. N08825 in hot finished annealed condition in Table A.12, A.13 and A.14. Table A.12 breaks down Solid solution nickel-based alloys into Type-4a, 4b, 4c and 4d depending on Cr, Ni+Co, Mo and Mo+W mass fraction and metallurgical condition. Now my question is whether ASTM B 423 (UNS N08825) pipe in hot finished annealed delivery condition for 8" and 10" pipe shall be acceptable for piping because for type 4a and 4b metallurgical condition does states the requirement of cold-worked or hot worked".

 

QUESTION 134:

 

Table 4 (for precipitation-hardenable, 6Mo alloys) (NACE MR0175/ISO 15156-3, Sub-clause A.9.2, Table A.33) permits elemental sulfur in the environment at 450°F, but not at 425°F, yet again at 400°F. Where does the user discover whether sulfur is or is not acceptable for applications between these temperatures? This is odd enough, but Table 6 (for 6 Mo, precipitation-hardenable 6 Mo alloys) (NACE

MR0175/ISO 15156-3, Sub-clause A.4.2, Table A.14) does allow sulfur at 425°F. Are the precipitation-hardenable versions of these alloys more resistant to cracking than their solution-annealed and cold-worked analogs?

 

 

QUESTION 135:

 

(a) Table 6 (NACE MR0175/ISO 15156-3, Sub-clause A.4.2, Table A.14) permits sulfur at 300°F in any H2S partial pressure, but not at 425°F. Where, if anywhere, between 425°F and 300°F are alloys in this category sulfur-resistant? If an oil- company client has a well with bottom-hole temperature of 350°F with produced brine that contains sulfur, will an alloy like 2550 (UNS N06975) be sufficiently resistant, or (b) must C-276 (UNS N10276) be deployed?

 

QUESTION 136:

 

Could you please confirm that the kPa units of the H2S column of ISO 15156-3, Table A.14 are incorrect and that the units should be MPa not kPa?

 

QUESTION 137:

 

NACE MR0175/ISO 15156-3: We make bellows for use in Safety Relief Valves. We use all nickel alloy materials but we are particularly concerned with Inconel 625/Inconel 625LCF. In previous editions of the NACE standard, the material hardness value for UNS N06625 is clearly stated as being acceptable to 35 HRC maximum, but in the above-referenced latest edition we are finding it difficult to trace this requirement and keep our records and practices updated. Would you please confirm the hardness requirements stated in the above-referenced latest edition and also reference relevant paragraphs and tables.

 

We buy the strip material in the solution-annealed condition, but there is a certain amount of work hardening that takes place during the bellows forming process.

 

QUESTION 138:

Does Monel in the annealed condition in accordance with ASTM B 127 and Monel in the as-cast condition in accordance with ASTM A 494 M-35-2 and M-30C meet NACE Standard MR0175-2003?

 

QUESTION 139:

 

This question relates to NACE MR0175/ISO 15156 Part 3, Appendix A, Paragraph A.4.3. Is the hardness testing survey required as part of the welding procedure qualification for solution heat-treated nickel-based alloys welded with solid-solution nickel-based weld metal? In accordance with A.4.3 there are no hardness requirements.

 

A.4.3 Welding solid-solution nickel-based alloys of this materials group. The requirements for the cracking-resistance properties of welds shall apply (see 6.2.2).

 

The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable.

 

There are no hardness requirements for welding solid-solution nickel-based alloys with solid-solution nickel-based weld metal.

 

Is the hardness testing survey required as part of the welding procedure qualification for solid solution nickel-based alloys (as addressed in NACE MR0175/ISO 15156-3, A.4) welded with solid-solution nickel-based weld metal?

 

QUESTION 140:

We need clarification of Paragraph 4.8.2—Low-Carbon Martensitic Stainless Steels. In the 2002 edition this was Paragraph 3.7.2.1. The 2002 edition allowed wrought material meeting the chemistry requirements of ASTM A 487 CA6NM. The 2003 edition appears not to allow these F6NM wrought materials (UNS S41500), just S42400, which is not the same thing. Please advise whether this material is acceptable.

 

QUESTION 141:

 

My inquiry concerns CA6NM: In the old MR0175-2002 this material is discussed in Paragraph 3.7.2.1. In this paragraph there is a note (12) stating that the hardness correlation in ASTM E 140 doesn’t apply to CA6NM and that for this material the maximum permissible value (in Brinell) is 255 BHN.

 

In the new MR0175/ISO 15156, this statement is no longer used. There is, however, a paragraph in Paragraph 7.3.2 of MR01756/ISO 15156-2 which stipulates that users can establish hardness correlations for individual materials. Please see below:

 

For ferritic steels EFC Publication 16 shows graphs for the conversion of hardness readings, from Vickers (HV) to Rockwell (HRC) and from Vickers (HV) to Brinell (HBW), derived from the tables of ASTM E 140 and BS 860. Other conversion tables also exist. Users may establish correlations for individual materials.

 

Finally the questions:

Is CA6NM acceptable per MR0175/ISO 15156 at a hardness of max 255 BHN which has been (empirically) determined to be the equivalent of 23 HRC (but which on the ASTM E 140 scale corresponds to about 25 HRC)?

 

 

QUESTION 142:

 

My question is about SS 431 (wnr 1.4057/S43100) which is a martensitic stainless steel.

 

In Part 3 of the documentation, according to A.6 Martensitic (stainless) steels (identified as individual alloys) and Table A.18. Environmental and materials limits for martensitic stainless steels used for any equipment or components.

 

As the alloy SS 431 (wnr 1.4057/S43100) is not mentioned, does that mean that it cannot be used according to NACE or can we use it as long as the hardness of the material is max. 22 HRC?

 

Do we need to apply any special attention to the heat treatments, as shown in Table A.18?

 

 

QUESTION 143:

 

I have a question regarding NACE MR0175/ISO 15156-3:2003. On Table A.18, the heat treatment requirements for CA6NM and F6NM are listed. Is this the only approved heat treatment? If we follow this heat treatment initially, are other heat treatments allowed as long as they do not exceed the original? We're trying to find out if a supplemental stress relieve is acceptable to try and lower the material hardness.

 

QUESTION 144:

Inconsistency between Table A.18 and A.23 of Para. A.6.2 in NACE MR0175/ISO 15156-3:2003. Table A.18 allows martensitic stainless steels for any equipment or component, but Table A.23 excludes casing and tubing hanger and valve stems. What is the meaning of any equipment or component? Does any equipment or component from Table A.18 exclude casing and tubing hangers and valve stems?

 

QUESTION 145:

 

Is the maximum hardness limit for ISO 11960 L-80 Type 13 Cr tubing used as a downhole tubular component, packer, and other subsurface equipment in accordance with NACE MR0175/ISO 15156 the maximum hardness as specified in the latest edition of ISO 11960?

 

Note: ISO 11960 is also designated as API 5CT.

 

Note: ISO 11960 currently specifies 23 HRC as the maximum hardness for L-80 Type 13 Cr tubing.

 

Discussion: NACE MR0175/ISO 15156-3, Table A.19 lists ISO 11960 L-80 Type 13 Cr and two other materials as begin acceptable for "downhole tubular components, packers, and other subsurface equipment."

 

There are notes in this table that specify the maximum hardness limits of the other two materials, individually. However, there is no note to specify the maximum hardness limit of ISO 11960 L-80 Type 13 Cr tubing.

 

This seems to indicate that ISO 11960 becomes the controlling document for L-80 Type 13 Cr, and therefore the maximum hardness for ISO 11960 L-80 13 Cr tubing is currently 23 HRC as specified in Table C.6 and Table E.6 of ISO 11960.

 

QUESTION 146:

 

I need to clarify a confusion about NACE MR0175/ISO 15156-3:2003 (E).

 

Why are tubing and subsurface equipment in Tables A.19 and A.20, respectively, treated as two separate categories? Tubing itself is subsurface equipment so why is it treated separately? Moreover, K90941 as mentioned in Table A.20 is recommended for subsurface equipment under any H2S partial pressure but not for tubing, exposed to the same condition; why? L-80 type 13 Cr is more cracking- resistant material than K90941; still it is not recommended for subsurface equipment apart from tubing; why?

 

We are in a process of developing a sour gas field and purchased a copy of this standard to be a guideline for material selection. We need answers to these questions so we can select the most appropriate material for downhole casing/tubing.

 

 

QUESTION 147:

 

In the 2002 version of MR0175, the maximum hardness requirement for duplex UNS S32550 was covered in Paragraph 3.9.1. This same material is now covered in Paragraph 4.9 of the 2003 version of this standard, but the hardness requirement seems to be missing. Has the hardness requirement been dropped for this material, or is the hardness assumed to be acceptable as long as the material has been solution annealed and liquid quenched?

 

 

QUESTION 148:

 

What is the foundation for limiting forged and cast UNS S31803 (Paragraph 4.9.3) to a maximum partial H2S pressure and temperature while the hot isostatic pressure- produced equivalent (Paragraph 4.9.4) is only limited to maximum hardness?

 

 

QUESTION 149:

 

Zeron 100: Old (2002): Paragraph 3.9.6/3.9.7: pH2S <0.2 bar (20 kPa) and 120 pH2S <1 bar (100 kPa) and 15 g/L Cl- and pH >5.6

New (2003) Paragraphs 4.10 and A24: pH2S <0.2 bar (20 kPa) only: What is the technical justification for this change?

 

 

QUESTION 150:

 

The question is in regard to Appendix A.7 of NACE MR0175/ISO 15156-3:2003(E). In A.7.3 third paragraph, it requires that "the microstructure ... shall have grain boundaries with no continuous precipitates". Is there any guidance as to what continuous means? For example, does it mean continuous throughout the microstructure?

 

Our laboratory has reported suspected continuous precipitates "at some locations".

 

 

QUESTION 151:

 

ISO 15156-3, A.7.3--Regarding metallographic examination of the microstructure:

 

 (a) Do closely spaced spheroidal precipitates such as grain boundary carbides constitute continuous precipitates?

 (b) At what spacing would closely spaced spheroidal precipitates be considered continuous?

 (c) Are the quantification of precipitates (intermetallic phases, nitrides, carbides) to be evaluated as a volume fraction relative to the bulk sample?

 (d) In cases where only grain boundary precipitates are observed, is the quantification to be made as a volume fraction relative to the bulk sample or as a lineal fraction relative to grain boundary length?

 (e In the absence of intermetallic phases and nitrides, does 1 vol.% represent the maximum allowable carbide precipitate content?

 (f) What is a suitable recommended practice or standard by which to perform this quantification?

 

QUESTION 152:

 

Can you please answer the following queries or pass to committee. These queries relate to welding of 22% Cr duplex/25% Cr duplex Annex A7, of MR0175/ISO 15156- 3, A.7.3 (2nd para) " The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal," When applied to ASTM A790 UNS 32760 (see attachment) only a Brinel hardness is given 270 BHN (28 HRC equiv.).

This is a reduction of 6 HRC from the 34 HRC allowance in NACE MR0175:2000.

 

If no HRC limit is given in the material specification do we assume no maximum HRC hardness limit or use the Brinel hardness specified (28 HRC equiv.).

 

Alternatively do we revert to the referenced NACE MR0175 [14] and assume 34 HRC.

 

QUESTION 153:

What grade of stainless steel meeting NACE requirements can be used for a tubing hanger when the pH is <3.5?

My interpretation based on understanding Paragraph 9.2 of NACE MR0175 and Section A.8 of ISO 15156 is that only UNS S66286 is acceptable. Could you please confirm my statement or correct it?

 

QUESTION 154:

 

Table A.26 limits the precipitation-hardened austenitic steel UNS S66286 to 150°F and 15 psi H2S when chlorides are present.

 

(a) Can this material be used at higher temperature if no chlorides are present?

 

(b) Is this material included in the current ballot for austenitic steels which (apparently) would allow their use at a higher temperature if no chlorides are present?

 

(c) Would the MP consider adding an unrestricted clause for the use of this material for valve stems, pins, and shafts (similar to Table A.3 for UNS S20910)? This material would perform much better as a valve stem in H2S environment than the cold-worked Nitronic 50.

 

QUESTION 155:

 

Does NACE MR0175/ISO 15156-3 Table A.26 apply to Gr. 660 material used in subsea bolting applications external to the production wellbore environment when indirectly heated above 150°F?

 

QUESTION 156:

Reference: NACE MR0175/ISO 15156-3 Table A.27--Environmental and materials limits for martensitic precipitation-hardened stainless steels used for wellhead and christmas tree components (excluding bodies and bonnets), valves and chokes (excluding bodies and bonnets) and packers and other subsurface equipment

 

API 6A makes a distinction between hangers and body components. NACE MR0175/ISO 15156 doesn't define either. This has led to some confusion regarding whether or not UNS S17400 material may be used as hangers in a sour environment.

 

(a). Does the exclusion of wellhead "bodies and bonnets" in Table A.27 also mean that hangers are excluded?

 

(b). Are hangers considered "subsurface equipment" in the context of Table A.27?

 

(c). Does Table A.27 prohibit the use of UNS S17400 material for hangers in sour service?

 

QUESTION 157:

If both Paragraphs 9.2 and 9.5 are applicable, as we believe they are, can we select which paragraph we follow when they cover the same component or materials? Does Paragraph 9.4 apply to choke valves?

 

QUESTION 158:

 

Paragraphs 9.2.4.1 and 9.5.2. Why is it that UNS S17400 can be used for pressure- containing wellhead and Christmas tree components (Paragraph 9.2.4.1) but not for pressure-containing valve components (Paragraph 9.5.2)?

 

QUESTION 159:

17-4 pH: Old (2002): Paragraph 3.8.1. Only requirement: HRC 33

 

New (2003): Paragraph 9.2.4.1 and A27: pH2S <0.034 bar: Technical justification?

 

QUESTION 160:

Can you provide clarification on Paragraph 9.5.7: ―UNS S17400 …. has been used in service tool applications at the surface when stressed at less than 60% of its minimum specified yield strength under working conditions. Paragraph 9.5 is concerned with Internal Components for Valves, Pressure Regulators, and Level Controllers. What exactly do service tool applications encompass?

 

QUESTION 161:

SUBJECT: Paragraph 11.4.5 of NACE MR0175-2003 Standard

QUESTION: Are wrought UNS S17400 and S15500 martensitic precipitation- hardenable stainless steels that meet the hardness and heat-treat requirements of Paragraph 11.4.5 of NACE MR0175-2003 acceptable for use in compressors in sour environments with no environmental limits with respect to chloride content, partial pressure of H2S, temperature, and free elemental sulfur?

QUESTION: If the answer to the former question is no, what are the specific environmental limits?

 

QUESTION 162:

 

SUBJECT: Paragraphs 11.4.4 and 11.4.6 of NACE MR0175-2003

(a) Are the martensitic stainless steels that are listed in Paragraphs 11.4.4 and 11.4.6 of NACE MR1075-2003 and meet the hardness and heat-treat requirements specified in their respective paragraphs acceptable for use in compressors in sour environments with no environmental limits with respect to chloride content, partial pressure of H2S, temperature, and free elemental sulfur?

(b) If the answer to the former question is no, what are the specific environmental limits?

(c) Are the answers to the above questions in agreement with ISO 15156?

 

QUESTION 163:

 

The precipitation-hardenable version of G-3 has no environmental limits per Paragraph 4.15.6 of the 2003 edition. "Conventional wisdom" has it that a solution- annealed and cold-worked nickel-based alloy is more resistant to environmental cracking than its precipitation-hardenable clone.

 

QUESTION 164:

I think that the (Cartesian) coordinates in Table 3 (NACE MR0175/ISO 15156-3, Sub-clause A.9.2, Table A.32) {T 390°F, pH2S 360 psi} may have come from data supplied by me to NACE from my office files for recommendations made to oil companies for Alloy 925 (UNS N09935). If so, I have no confirmation that the oil companies ever deployed equipment made from Alloy 925 in these environments. I recommend that NACE remove these data from Table 3, replacing them with test

data from Battelle showing cracking resistance at 450°F, pH2S 400 psi in 15% Cl and also a second set of coordinates at 425°F, pH2S 300 psi in the presence of elemental sulfur (Hibner).

 

 

QUESTION 165:

 

Our question relates to ISO 15156-3, Table A.32:

How should the table be interpreted in terms of the maximum allowable temperature for applications with less than 30 psi partial pressure of H2S?

 

For example, in its current layout the table prohibits the use of UNS N07718 at temperatures higher than 450°F at any H2S pressure below 30 psi.

 

QUESTION 166:

 

Table 4 (for precipitation-hardenable, 6Mo alloys) (NACE MR0175/ISO 15156-3, Sub-clause A.9.2, Table A.33) permits elemental sulfur in the environment at 450°F, but not at 425°F, yet again at 400°F. Where does the user discover whether sulfur is or is not acceptable for applications between these temperatures? This is odd enough, but Table 6 (NACE MR0175/ISO 15156-3, Sub-clause A.4.2, Table A.14) (for 6 Mo, precipitation-hardenable 6 Mo alloys) does allow sulfur at 425°F. Are the precipitation-hardenable versions of these alloys more resistant to cracking than their solution-annealed and cold-worked analogs?

 

QUESTION 167:

(a) Does NACE MR0175 / ISO 15156 apply to the spring application as depicted in figure 1, when areas of the spring are plastically deformed (not more than 1 or 2% strain)?

(b) Why does NACE MR0175 / ISO 15156, Part 3 specifically demand age- hardening although age-hardening typically increases the hardness of UNS R30003? Is this because problems were reported when the material was not age-hardened, because data is only available for age-hardened material, or another reason?

 

QUESTION 168:

Because UNS C72900 and C96900 are copper alloys, are they, by definition, covered by Section 4 of NACE Standard MR0175, which basically states copper alloys are suitable for use without restriction other than as noted in the footnote, which informs the user that such materials may exhibit accelerated general weight- loss corrosion in some sour environments?

 

 

QUESTION 169:

 

Paragraph 1.5.1 of NACE Standard MR0175-2003 states that ―SCC may be controlled by any or all of three measures: (1) using the materials and processes described in this standard; (2) controlling the environment; or (3) isolating the components from the sour environment.

 

My client has an application in which Inconel 625 weld metal is overlay welded onto a martensitic steel component. The martensitic steel component base material and heat-affected zones are isolated from the fluids by the Inconel 625; all wetted surfaces are Inconel 625.

 

My client’s customer believes the base material must be stress relieved in accordance with Paragraph 5.2.1, which states: ―Overlays applied to carbon and low-alloy steel or to martensitic stainless steels by thermal processes such as welding, silver brazing, or spray metallizing systems are acceptable for use in sour environments, provided the substrate does not exceed the lower critical temperature during application. In those cases in which the lower critical temperature is exceeded, the component must be heat treated or thermally stress relieved in accordance with procedures that have been shown to return the base metal to the base metal hardness as specified in this standard.

 

We believe that Paragraph 5.2.1 does not apply since the base metal is isolated from the sour environment with Inconel 625, which is acceptable to 35 HRC.

 

QUESTION 170:

 (a) Subject: Equivalency of the technical content of both MR0175-2003 and MR0175/ISO 15156 in relation to the use of Stellite 6 cladding.

 

Question: In NACE MR0175-2003 cobalt-based alloys (e.g., Stellite 6) are acceptable for hardfacing applications (Section 5, Paragraph 5.2.5).


In NACE MR0175/ISO 15156, Paragraph A.13.2.2 states "the cracking resistance of alloys specifically designed to provide hard-facing is not specified in this part of NACE MR0175/ISO 15156." Is there perhaps another part of this specification that we may have overseen?

 

(b) Subject: Solid Stellite 6 Castings.

Question: Are solid Stellite 6 castings are permitted for wear-resistant parts in valves under the MR0175/ISO 15156 regime?

 

QUESTION 171:

We believe that the inclusion of some alloy trade names in the second columns of ISO 15156-3, Annex D Tables D.1-D.12 is in conflict with the NACE policy on the use of trade names in standards. Could the Maintenance Panel please propose steps to resolve this policy problem?

 

 

QUESTION 172:

 

It is our understanding of NACE MR0175/ISO 15156 that provided ASTM A 995 Grade 4A (UNS J92205) 22 Cr duplex stainless steel complies with the materiallimits of Table A24 of Annex A, it can be selected for use in H2S-containing environments provided the environmental limits given in Table A24 are not exceeded.

 

QUESTION 173: It does not ALSO have to be listed in Annex D Table D7, which we believe is for information only and lists only SOME duplex stainless steels.

 

QUESTION 174:

 

Could you please confirm that the information given for alloy UNS N08367 in NACE MR0175/ISO 15156-3, Table D2 is incorrect and should be that shown below for the elements affected?

S maximum should be 0,03

N range should be 0,18 to 0,25 Cu range should be 0,00 to 0,75 FPREN should be 42 to 49

Ni + 2 Mo should be 35,5 to39,5

 

QUESTION 175:

 

(a) In Table D2, the alloy N08367 was assigned a PREN of 20 - 23. Calculations based on Cr +3.3 Mo yields much higher PREN (40 - 45). If this was a mistake, please correct.

 

QUESTION 175 (b):

In NACE MR0175/ISO 15156-3 Table D.6, F6NM is associated with UNS S42400.

In ASTM A182, F6NM is associated with UNS S41500. But composition listed in Table D.6 for F6NM does not match either one of these UNS numbers. Is there a reason for that or is it a mistake? The composition is similar to both but does not match up.