CRA-Compass®: Your Guide to Corrosion Resistant Alloys - Corrosion Prediction, Selection and Application Limits for Resistance to Pitting, Crevice Corrosion and SSC/SCC
Performance Functionality Usability
Anytime Anywhere Any Device Any OS
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Features and Component Modules of CRA-Compass
CRA-Compass consists of the following standalone modules:
Overview of CRA-Compass for Production Tubing
This module deals with the selection and application limits of common corrosion resistant alloys used in the oil and gas production system as per international standard ISO 15156. Users of CRA-Compass simply enter the production data, the software will compute the in-situ pH as per ISO 15156, the pitting resistance equivalent number (PREN) as per ISO 15156, the corrosion rate when the selected alloy is used below the temperature limit, the SSC environmental severity as per ISO 1516, the CRA's susceptibility to SSC and SCC. Figures 1 and 2 below show the screen shots of this module.
Overview of CRA-Compass for Waters and Brines
This module deals with the application limits of 55 common corrosion resistant alloys used in water systems including natural seawater, chlorinated seawater, brines, produced water, formation water, brackish water, groundwater, fresh water, and potable water. Users can define their own alloys for CRA-Compass to evaluate the application limits for their resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC) under the specified operating conditions. The performance of the CRAs in coastal/marine environment is also included in this module.
Figure 3 below shows the overview of the CRA-Compass for waters and brines. The user simply selects one of the 55 corrosion resistant alloys from the list or define his/her own alloy by entering the chemical compositions.
Figure 3 Overview of the CRA-Compass for Waters
After selecting or defining the alloy, the pitting resistance equivalent number, PREN, as defined in the International Standard ISO 15156, is calculated and displayed.
The next step the user needs to do is to select one of the two input parameters, the temperature or the concentration of chloride. If the user select the temperature as the input parameter (Figure 2), CRA-Compass will determine the application limit or the maximum concentration of chloride for the selected alloy in terms of its resistance to pitting and crevice corrosion. The probability of stress corrosion cracking (SCC) and the temperature limit for SCC are also determined. If the user select the chloride concentration as the input parameter, CRA-Compass will determine the application limit or the maximum temperature for the selected alloy (Figure 3) in both chlorinated and non-chlorinated waters in terms of its resistance to pitting and crevice corrosion. The probability of stress corrosion cracking (SCC) and the temperature limit for SCC are also determined. The critical pitting potential, Epit, for the selected alloy is computed by CRA-Compass and is displayed under the Output on Application Limit. This predicted value corresponds to the measurement in 3.5% NaCl solution at 30oC in the laboratory.
If an alloy is not in the built-in list, the user can select "User-Defined-Alloy" from the list and then enter the chemical compositions in the table as shown in Figure 6 below. The PREN number and all other predictions are then computed accordingly.
Figure 6 User-Defined-Alloy
Three performance indicators for the selected alloy in the coastal/marine atmosphere are predicted based on the results from 4 years field exposure: (1) the maximum depth of corrosion attack; (2) the form of corrosion (pitting, uniform corrosion, no corrosion); (3) the degradation rating number (RN) as per JIS G0595.
Overview of CRA-Compass for Acids and Alkalis (H2SO4, HNO3, H3PO4, HCl, HF, Acetic Acid, Formic Acid, NaOH)
Figure 6 below demonstrates the operation of CRA-Compass for Acids and Alkalis, which is similar to the operation of the CRA-Compass for Waters discussed above. The user simply select an alloy from the dropdown list, and then enter the temperature and concentration. CRA-Compass for Acids will determine the boiling point of the acid, and the predicted corrosion rate of the selected alloy at the specified temperature and concentration. In addition to that, CRA-Compass for acids will compute the iso-corrosion diagram for the selected alloy so as to give the user a complete picture of the corrosion behavior of the selected alloy across the entire range of acid concentration and temperature.
Figure 7 CRA-Compass for Acids and Alkalis
CRA-Compass, giving you the right directions in CRA selection and application.
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