Pipe Pressure Test Failure 7

[dik]

A portion of 8" dia pipe failed a pressure test. Failure was along the longitudinal welded seam. It is my understanding that ASTM does not permit welding within an 1" of the seam. Is this correct? and is it possible under some other regulation that the seam, with a proper welding procedure, can be rewelded to repair the damage.

Dik

 

[jmiles]

I believe by MT he means Magnetic Particle Testing.

I know ive come to this late, but yeah id have gottent eh lawyers involved a long time ago, replace all the pipe that came from that supplier.

Ive worked in Offshore and i know the kind of service life that is expected in alot of this stuff, and the usual quality standrds, this pipe ahs failed miserably. the sad thing is no matter how this works out its a lose lose situation, your losing fab time, its going to cost you money to rebuild it all and to source new pipe, things are bad all around really.

 

[ginsoakedboy]

dik,

This is an interesting thread, and I think everyone here can empathize with your situation. One encounters such ethical-economic dilemmas in the supposedly objective world of engineering with surprising frequency.

That being said, I find myself agreeing to most of the statements made by racookpe1978. Would like to hear more as the situation evolves, and wish you the best.

 

[lukeraider43]

Hi Dik

What was the outcome of the pipe in question

 

[dik]

Last I heard, they still don't have resolution on this...

Dik

 

[unclesyd]

Something I've learned the hard way is that you as an end user can not inspect integrity into a product. Despite all the codes, standards, and guarantees you still have to depend on the integrity of the manufacturer to produce the very best product needed to meet your specified requirements. Unless there an accident or injury your best bet is get rid of the problem to cut the losses.

We have had several hydrotest failures in CS piping over the years and If I recall correctly all were of the ERW variety slated for use in non hazardous service. We did have inservice failure of 10" Sch 80 welded pipe from fatigue, thermal, in 75 psig steam service. The origin of the failure was an area of LOF and LOP in the seam weld. All our failures were in domestic made pipe.

The same problem is found in SS piping. Take a look at the following thread to see what you can run into with such a failure. Since this thread was posted two other sticks of SS pipe, one SCH 40 and one SCH 80 have been found to contain LOF defects by the pipe fitters while prepping for welding. These pipe were by two different manufacturers. I don't have the spec for the pipe. This has resulted in the requirement that all end preps on SS pipe are to be PT tested..

Thread378-70822

The reference URL in the above thread has changed to the one below.

http://www.uscfc.uscourts.gov/sites/default/files/Mortenson.pdf

In my previous post I mentioned that the same problem had occurred at Vandenberg Air Force Base and I have sense learned that the same problem was found at the NASA Site in Mississippi except on a larger scale. I have heard that NASA wasn't very happy about the problem.

 

[brimmer]

MT will only show external or surface breaking indications, we would not know if the failed indication broke the surface until it actually ruptured which is why there is a need for UT here as well. MT won't show tight LoF indications in the weld even though material is only 1/4 inch thick. You are definitely on the right track with the material testing, good luck.