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The Corrosion Times
- Local and International News on Corrosion

Why Did the Bridge Fall?
Time Thursday, 2 August 2007

It may take several days to figure out how many people died in Wednesday's collapse of the I-35W bridge in Minneapolis yesterday - the official toll still stands at four, but nobody expects it to stay there. Between 20 and 30 people are still missing, and while some of them may be lying in hospitals, unconscious and unidentified, plenty of cars are still submerged in the Mississippi River. Anyone trapped inside - and there are such people - are no longer alive. So recovery crews are picking their way carefully around the twisted steel and broken concrete that could shift without warning in the muddy current.

Investigators, meanwhile, from the National Transportation Safety Board (NTSB) and from a private firm of forensic engineers hired by the state of Minnesota, have already arrived to begin trying to figure out what happened. That might not be easy. Sometimes a bridge collapses for glaringly obvious reasons - being whacked by a barge, for example. That's what knocked down Florida's Sunshine Skyway bridge in 1980, killing 35 people, and the I-40 bridge near Webbers Falls, Oklahoma, in 2002, killing 14, and a causeway in Louisiana in 1964, killing 14.

But in other cases - the Mianus River Bridge in Connecticut (three dead in 1983) or the Silver Bridge, spanning the Ohio River between Ohio and West Virginia (46 dead in 1967) - the cause is far more subtle. The former was triggered by metal fatigue in a single steel pin: when it finally failed, the loss of support transferred excess stress on other parts, which couldn't handle it, failing in turn. The latter was finally traced, again, to a single piece of metal, which had been forged with a tiny, unnoticed crack that weakened further with corrosion.

Corrosion may have played a role here as well: the Minneapolis bridge - what's known as a deck steel truss bridge - was a concrete roadway supported by gridwork of steel. "When you use both concrete and steel like this," says William Miller, an expert on bridge engineering at Temple University in Philadelphia, "there can be chemical reactions going on where these two very different substances meet. This is especially a problem in extreme climates where water can get into the cracks between supports, freeze and expand and cause a huge amount of damage." Beyond that, says Miller, "concrete is a very forgiving material, and so it can stand up to a lot of cracking and wear. Steel on the other hand, cannot." In a place like Minnesota, where road crews dump corrosive ice melter on roadways by the ton in winter, the problem is even worse.

But since civil engineers know all this, how come they didn't spot the weak points? It may well be that the real breaking point was hidden, or simply wasn't obvious under normal inspection. In fact, as everyone knows by now, the bridge was deemed "structurally deficient" starting in 1990. That didn't result in an emergency repair order, but rather an intention to replace the bridge by 2020 - not unusual, evidently, since the designation doesn't suggest imminent danger. According to Minnesota Gov. Tim Pawlenty, speaking Thursday afternoon at a press conference, there are no fewer 70,000 to 80,000 bridges in the U.S. in the same category; at least another 80,000 are considered "functionally obsolete," or not up to current design standards, another label that fails to testify to a structure's safety for travel.

Minneapolis Bridge Collapse Killing 7
AP Wednesday, 1 August 2007

MINNEAPOLIS - An interstate bridge jammed with rush-hour traffic suddenly broke into huge sections and collapsed into the Mississippi River Wednesday, pitching dozens of cars 60 feet into the water and killing at least seven people.

The steel-arched bridge, which was built in 1967, rose about 64 feet above the river and stretched about 1,900 feet across the river. The bridge was built with a single 458-foot-long steel arch to avoid putting any piers in the water that might interfere with river navigation. The bridge was scheduled for inspection this fall.

Sony Recalls Digital Cameras Over Metal Plating Defects
30 July 2007

30 July 2007 - Sony is recalling 416,000 digital cameras because the case may warp, creating an edge that can cut or scratch the user's hands. Sony has issued a safety alert about certain batches of its "Cyber-shot" DSC-T5 digital still camera. The metal plating on the bottom of the camera unit may warp, causing slight cuts or scratching to the skin of the user. The metal plating of some DSC-T5 units may peel away from the camera unit and warp outward. The adhesive strength of the metal plating is too weak, so damage to the bottom casing can cause the plating to peel away and warp outward. The manufacturer is offering a free replacement of the bottom casing. Sony says that although the metal plating of units with other serial numbers may peel away if dropped or exposed to some other external impact, the plating will not warp. The recall affects 350,000 Cyber Shot DSC-T5 cameras sold in the United States, Europe and China, and about 66,000 sold in Japan, Sony spokeswoman Ryoko Takagi said.

NYC explosion of steam pipe 'like a volcano'
USA Today  Wednesday, 18 July 2007

NEW YORK — A steam pipe blew up near Grand Central Terminal on Monday and sent thousands of people running out of buildings in a panic that it was a terror attack. "The building started shaking. There was steam and smoke billowing out of the ground," said Bryan Kohler, an accountant who works from a seventh-floor office on Third Avenue. "Everybody panicked. You know what it's like now. We grabbed our stuff and ran."

The pipe blew at about 6 p.m., the height of rush hour, and sent a geyser of mud, steam and scalding water into the air on 41st Street, according to witnesses. White steam clouds rose as high as the nearby 77-story Chrysler Building. One person was killed and 26 others were wounded as the ruptured pipe sent thick plumes of smoke and ash into the air.
 

New York City still uses steam to heat and cool many buildings, including the Empire State Building. In 1989 a steam explosion ripped through a street, killing three people. The 2-foot pipe that burst Monday was installed in 1925.
 

CTE TUNNEL CEILING SLAB COLLAPSE LTA to take preventive measures
The Straits Times Wednesday, 23 May 2007

CENTRAL Expressway (CTE) tunnels will now be inspected more closely and frequently, the Land Transport Authority (LTA) said yesterday - two weeks after a concrete slab the size of a car's bonnet fell from a tunnel ceiling.

The checks will be carried out every three months on stretches which are under waterways, and every six months in other areas. Previously, the inspections were conducted once a year. The LTA said also that it will apply an electrochemical treatment - zinc hydrogel anode - to tunnels located under waterways. The zinc reacts with the steel in the concrete to form a weak electrical current - as in a battery - which helps impede corrosion. On the evening of May 9, chunks of concrete from the ceiling of a south-bound tunnel, which goes under the Singapore River - fell onto the road. Miraculously, no vehicles were hit. The cause has been identified as concrete spalling, which happens when steel beams in concrete rust and expand. The tunnels have been troubled with water seepage since the CTE opened in 1991, though millions of dollars have been spent to arrest leaks at nearly 2,000 points.

Yesterday, the LTA reiterated that the tunnels are structurally safe. It said that spalling "will not lead to a reduction in strength of the structure if attended to with proper repairs". However, certified corrosion specialist Qiu Jianhai told The Straits Times that "spalling concrete is just a visible surface problem signalling the start of the deterioration of the structure". He said that if corrosion control had been incorporated at the point of construction, it would have been cheaper. Dr Qiu, incidentally, also advocated the zinc hydrogel treatment.
 

Falling Concrete in CTE Tunnel Engineers, MP call for thorough check
The Straits Times Friday, 11 May 2007

TROUBLED with leaks from the time it opened in 1991, the Central Expressway (CTE) tunnels should be given a thorough check to prevent more slabs of spalling concrete from smashing onto the road. This was what civil engineers, motorists and the deputy chairman of the Government Parliamentary Committee (GPC) for Transport said yesterday, after chunks of concrete came crashing down around 8pm on Wednesday.

This happened on the southbound CTE tunnel towards the Ayer Rajah Expressway, near the Havelock exit - a stretch that is built under the Singapore River. Miraculously, the slabs did not hit any vehicle at what is usually a fairly busy time of day in the tunnel. The Land Transport Authority (LTA) says the tunnel was safe and Wednesday's incident was "an isolated one". LTA chief engineer Paul Fok said checks are done regularly to spot and fix any defects. On top of that, professional engineers inspect all tunnels "at least once every five years" to certify their structural integrity. He added: "The structural integrity of the CTE tunnels is not affected. We have checked the surrounding areas and found no areas of concern." The authorities have insisted that leaks are common in tunnels the world over, although tunnel builders that The Straits Times spoke to say that watertight tunnels are feasible to construct. "There are sections of MRT tunnels here that are dry, even those going under rivers. But others leak," said a construction source. "It all depends on time, cost and the quality of people who designed and built the project."
 

'Why wasn't pipeline pigged?'
Anchorage Daily News, 14 Oct. 2006

Alaska's congressional delegation on Friday grilled BP executives and government regulators about Prudhoe Bay oil leaks and, in particular, this week's revelation that state officials had ordered BP to clean sludge out of key pipelines in 2002 but let the company off the hook three months later.

Federal pipeline regulators believe the sludge that BP allowed to accumulate inside the pipes for many years might have harbored corrosives that ate holes through the steel, leading to a 201,000-gallon oil spill last winter and a second leak in early August that forced an emergency partial shutdown of the nation's largest oil field.

BP TRIAL: Browne called to testify over refinery blast
Financial Times, 18 Sept. 2006

Plaintiffs’ lawyers who earlier agreed not to call Lord Browne, BP’s chief executive, to testify in the civil cases arising from last year’s fatal Texas refinery explosion, said they now intended to question the head of the UK oil group.

Mr Buzbee said he would ask Lord Browne about BP’s practices across the US, including Alaska, where the company had to shut half its oilfield because of severe corrosion, to determine whether the company has a pattern of neglect, underfunding and underinvestment. “There is a whole bevy of topics I want to bring up with Lord Browne,” Mr Buzbee said.

Corrosive insulating paper triggered Sony's third laptop battery recall
The Straits Times Wednesday, 20 September 2006

TOSHIBA said yesterday that it will replace 340,000 faulty laptop batteries worldwide, in the third recall in two months involving Sony-made batteries. The latest recall brings the total number of Sony batteries recalled this year to about six million worldwide.

A Sony spokesman said the batteries involved in the latest Toshiba recall suffer from a different problem, caused by the corrosive effects of the insulating paper used in the battery packs.

Shell pays up after water gets into vehicles’ fuel tanks
The Straits Times Tuesday, 29 August 2006

FIVE vehicles which pulled into a Shell station in Palan Jurong Kechil recently were served watered-down petrol. An undetected puncture in an underground fuel pipe - 2mm wick and likely the result of corrosion - caused a substantial amount of water in the soil to get into the pump.

Vehicles which took in the adulterated petrol - four cars and a motorcycle - suffered varying degree of damages. For one owner, Shell agreed to throw in a two-year warranty on the car - on top of the three- ear new-car warranty - and $10,000 in compensation.

Corrosion, oil spill prompt shutdown of Alaskan oil field
AP: 7 August 2006

ANCHORAGE, Alaska (AP) - BP Exploration Alaska has begun shutting down the Prudhoe Bay oil field. The company says it has discovered unexpectedly severe corrosion and a small spill from an oil transit pipeline. Company officials say it will take days to shut down the field. Once the shutdown is complete, it's expected to reduce oil field production by 400,000 barrels a day. In a prepared statement, BP America Chairman and President Bob Malone says the company regrets that it's necessary to take the action. And he says the company apologizes to the nation and to Alaska "for the adverse impacts it will cause." Prudhoe Bay represents about half of Alaska's oil production and about eight percent of U-S production, according to the US Energy Information Administration.

HDB's vow: Fewer defects, longer warranties
The Straits Times Wednesday, 29 September 2004

THE Housing Board has vowed to reduce the cases of spalling concrete and water seepage in its new flats - and hopes to back it up with much longer warranties against these defects.

Even if 1 or 2 per cent of flats have such problems, 'it's a lot', said HDB chief executive Niam Chiang Meng during its annual report briefing on Monday.

The board has asked a new building quality department to see how common defects can be prevented, he said. And he has 'challenged' his staff to eventually offer 10-year guarantees against spalling concrete and five-year ones against water seepage.

Seepage in new flats has been an issue recently, as most home owners have to pay the cost of repairs once the one-year defect liability period - when faults are fixed for free - expires.

In the first six months of this year, 21 flats less than 10 years old had spalling concrete. This is when ceilings crack when steel bars embedded in concrete corrode and expand. Based on that figure, two out of every 10,000 such flats have the problem each year.

In the first half of this year, 372 flats less than five years old also had water leaking through their ceilings. This works out to seven out of every 1,000 such flats each year.

The figure for water seeping in through walls was 444, or eight out of every 1,000 flats less than five years old each year.

Killer Windows: The heat is on to retrofit windows
The Straits Times Monday, 8 September 2004

A HOME owner with casement windows five years old or more who does not change the aluminium rivets to stainless steel ones by 30 September 2005 faces a maximum fine of $5,000 or six months' jail, or both.

He also faces fines of up to $500 for each day after his conviction that he still does not do the retrofitting. The changes were made to the Building Control Act passed by Parliament last Wednesday.

The Act had been amended in 1999 to allow for a maximum penalty of $5,000 fine and six months' jail for those who did not make their air-conditioners safe from falling by Sept 30, 2000.

With the current amendment, the Government's powers will be broadened to include all external features of a building that could pose a danger to the public and to impose a daily fine for those who refuse to act after a conviction.

The new law was prompted by the rise in the number of falling windows from just 19 in 2000 to 106 last year, mostly from HDB flats. Up until last month, 84 cases were reported this year and all were from HDB flats.

Lamp post corrosion: Three experts split
The Straits Times Tuesday, 8 June 2004

A THIRD expert witness, testifying in a coroner's inquiry into the death of a teenager hit by a falling lamp post, has added to the array of opinions over which part of the post was most severely corroded.

Associate Professor Qiu Jianhai, 41, a corrosion expert from the Nanyang Technological University's School of Materials Engineering, said corrosion occurred exactly at the ground level.

Earlier in the inquiry, two expert witnesses had been divided on whether the lamp post was corroded above or below ground level. This is central to the issue of whether a person doing a visual check of the lamp post could have seen the rusted area and taken action that might have prevented the fatal incident.

On Feb 28 last year, secondary school student Tay Wei Yi, 13, was playing volleyball at a Tampines basketball court when the lamp post fell and hit him on the head. A senior property officer with Tampines Town Council's managing agent had visually checked the lamp post three weeks before the incident but had not noticed any defects.

Dr Qiu said the most severe corrosion took place not above or below ground, but just at ground level. The 'junction' between the atmosphere and the soil would be the most severely corroded because of the 'wetting and drying' process due to collected rainwater, he said.

LTA spends $4m to tackle CTE water leaks for third time
The Straits Times Friday, 5 September 2003

Sony Digital Camera DSC-P1 Battery Issue
Wednesday, 16 April 2003

Sony has released a statement on its support site about a potential issue affecting some of its Cyber-shot DSC-P1 digital cameras. The cameras may exhibit shorter time between charges and/or the inaccurate indication of the need for battery recharging. The issue seems to be caused by corrosion on the connection between the AC adaptor and the camera. This symptom often results from accumulated corrosion at the connection between the supplied AC adaptor and the DSC-P1 camera.

Boy hit on head by lamp post dies
The Straits Times Wednesday, 7 March 2003

Tay Wei Yi, the 13-year old boy who was hit on the head by a lamp post which was fell over last week, died yesterday morning at Changi General Hospital.
 

Tragic Collapse: Boy hit by falling lamp post
The New Paper  Sunday 2 March 2003

A Tampines teenage is fighting for his life after being hit by a falling lamp post on Friday night.

Tay Wei Yi, 13, lies unconscious in the intensive care ward of Changi General Hospital.

He was playing with with schoolmates at a basketball court in Tampines when the accident happened around 7pm. A lamp post at the side of the court collapsed without warning, knocking him to the ground.