Why NOT to pneumatic test

[StressGuy]

There's an email going around now with pictures of the aftermath of this incident:

http://www.shanghaidaily.com/sp/article/2009/200902/20090207/article_390150.htm

Here's your key bullet:

The explosion occurred during a pressure test of the equipment, according to the city government media office. Workers were pumping air into a gasifier when some 500 meters of the piping network burst into fragments, buckling cement crossbeams.

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Looking at the pictures, this was clearly high pressure rated pipe, so I've no doubt the test pressure was quite high and the stored energy somewhere north of enormous.

I cropped one of the images out of the PDF file and attached it to this post. If you get to see the full file, definitely check it out.

To be certain, pneumatic testing has it's place. But, the large amounts of stored energy involved must be respected.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

 

[BigInch]

Ooooo! That one's going in my train wreck file.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[zdas04]

Maybe someday the data on target pressure total hoop stress etc. will emerge. Right now all anyone knows is that there was an explosion during pneumatic testing. I recently shut down a test because the ambient was less than the minimum I specified--violating that procedure would have put a half dozen people at risk and probably wouldn't have made the international press.

Any test is risky if there is not a competent test procedure or if the test procedure is not followed. I think I'll wait a bit on this one before changing behaviour.

David

 

[unclesyd]

Based on the picture and the following information in the video and press release I believe that something other than an overpressure existed. Looking the picture posted by StressGuy the scene was vaguely familiar with an explosion that I was privy to where there was an explosion that traveled several hundred yards and destroyed a lot of piping and a heater. I went looking and found the following additional information.

http://news.xinhuanet.com/english/2009-02/07/content_10779866.htm

http://www.shanghaidaily.com/sp/article/2009/200902/20090207/article_390150.htm

 

[MikeHalloran]

Judging, okay guessing, from the way it's crushed and buckled, the pipe in the movie looks awfully thin walled.





Mike Halloran
Pembroke Pines, FL, USA

 

[simplemath]

Not sure if any speculation added, but this is what I get from ex-coworker who was at the scene:
The blast happened at pneumatic testing a 500m length 36" natural gas pipe line. The testing pressure is 15.6Mpa. When the pressure reaches 12.3Mpa, a flange at the battery limit broke from the root of the hub, 3-4cm from the circ weld seam. The flange itself flied away 100m.The released air swing the pipe and totaled the gasifier and surrounding piping. The fracture is clear-cut. It is up to further investigation to find out the cause.


--It boils down to simple math--

 

[KENAT]

Reminds me why we'd test some pneumatics with a hydraulic test.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

 

[chicopee]

"I believe something other than overpressure existed" could it be that the piping, welding material and related materials were made in China? I always say buy USA!!

 

[FACS]

So, was the test a failure or success?

Charlie

http://www.facsco.com

 

[unclesyd]

FACS,

The test was a sucess, it found the defect in the piping.

I had 6 failures on some jacketed SS piping spools that required the spools to be broken down and the core pipe replaced. This took a lot of time and money but in the end I got an Attaboy because I insisted that all the spools be tested after being received from the fabricator who had graphited the shop test reports.

 

[uniqueflange]

it seems one month ago ,i havn't heard that though i was near shanghai .there are many accident we do not know .

mainly because corruption from the design to the purchase ,
every step...

many famous multinational company just know the market of china ,and used to it ,enjoy it as he want to survival in this fields