Out of spec welds

Some welder got out of town ahead of the posse.
http://www.startribune.com/local/south/92018749.html
Text here:Suspect pipeline weld prompts safety checks in 25 cities
Centerpoint says there are no immediate safety concerns. The problem surfaced in one welder's work for a national firm.
By MARY JANE SMETANKA, Star Tribune
Last update: April 24, 2010 - 9:53 PM
Welds on gas pipelines at 250 locations in 25 Minnesota cities are being spot-checked after a problem was discovered with work done by a welder for a contractor for Centerpoint Energy.
The problem was found in a weld last fall in southern Minnesota. Centerpoint says there are no immediate safety concerns.
However, the boring of holes in the ground to X-ray pipe welds could be disruptive in places like Richfield, where the work soon will affect sidewalks and landscaping surrounding the nearly new roundabout at 66th Street and Portland Avenue S.
"I've been with Richfield for 30 years and this has never happened before," said Mike Eastling, the city's director of public works.
Centerpoint spokeswoman Rebecca Virden said it will take several months for workers with Michels Corp., a pipeline and construction firm that did the welding, to re-check welds. While there are no gas leaks and pipes are functioning normally, she said, the utility has standards for welds that one Michels employee apparently didn't always meet.
The problem was discovered at a project in Kasota, Minn., at the end of the construction season, Virden said. She said a Centerpoint supervisor overseeing the work "didn't like the way the weld appeared, had it X-rayed and found it unsatisfactory." She said welds are supposed to be a certain thickness to prevent problems that can occur when the ground freezes and contracts.
"There is no leakage; it's about future reliability," she said. "It is not a safety issue at this point, but it's not up to code and standards, and it's not acceptable."
The welder, who worked for Michels in 2008 and 2009, is no longer with the firm, according to Centerpoint. Virden said that Michels, which is responsible for re-checking welds, has checked welds at about one-fifth of the locations where the welder worked and hasn't found other problems so far.
Most of the welds that are being checked are on service lines that come out of steel gas mains, Virden said. Michels, a national firm based near Fond du Lac, Wis., specializes in construction work for utilities. It has been a contractor for Centerpoint since 2003, and Virden said Centerpoint has been happy with Michels' work.
Bob Osborn, vice president for Michels' pipeline division, said he is not familiar with the details of the Minnesota case. He said problems with welders are rare. Those who work on gas pipelines undergo extensive training and are retested every six months to make sure they meet job standards.
"Utilities are under more scrutiny than ever," Osborn said. "That this is happening is really kind of a positive."
Hennepin County, which issued permits allowing Michels to spot-check welds, is requiring that the contractor restore sidewalks and landscaping around Richfield's roundabout to new condition. Unless faulty welds are found, the disruption at 66th and Portland should be confined to sidewalks and landscaping areas, because city engineers required that much of the new pipe that was laid there not be directly under the roundabout.
Mary Jane Smetanka 612-673-7380
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I thought that they have robot pipe welders that make perfect, consistent welds every single time. Why aren't those being used? Or are those robots for factories only?
i
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The article mentions "service lines that come out of steel gas mains". I take that to mean the 1" lines that welded to the side of a 4" or 6" pipe. A lot of these welds are run with line pressure in the pipe using a special drill rig: weld stub on, clamp on the rig, use a hole saw through the rig to cut hole in pipe, disconnect everything leaving a suitable valve on the end of the stub.
I see a lot of 4" plastic pipe replacement for the older steel pipe in residential areas.
On 4/25/2010 9:58 PM, Ignoramus24857 wrote:

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RoyJ wrote:

So they're making all this fuss because of a single bad weld that was found on one active project during normal inspection? All the other projects were inspected as they were completed, no?
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RoyJ wrote:

-- snip --

Kinda cool to know that there are companies out there that won't just sweep this sort of thing under the rug.
It probably helps that it was a contractor finding a problem with a sub -- one wonders if they would have generated all the expense for themselves if it had been their own welders, or if they couldn't put the welding sub on the hook for the expense.
--
Tim Wescott
Control system and signal processing consulting
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