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Pipe Pressure Test Failure 7

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dik

dik

Structural
Apr 13, 2001
25,583
CA
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
 
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hmmmmmmmm.... more out of curiousity - what material? (carbon steel?) What wall thickness/schedule? What test pressure?

I have not heard of the 1" seam rule, but am aware of branch connections through seams, which are allowed - however there are also specific provisions in the ASTM (ASME) specifications that provide for repair welding for certification (approved by the purchaser, of course) With general reference to A-530.
 
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What nonsense. Most of the time you can't see the seam. Even when you can, a girth weld that can't approach the seam within 1-inch would actually leave a two inch hole in the pipe near each seam (call it a 4-inch gap 1/16 inch wide, pretty big hole).

I have never heard of an ERW seam failing in a test (these seams are prone to MIC and other types of cathodic corrosion when they are standing in water, but that failure is always some time after the test). I've had hydrotest failures, but never at the seam or at a girth weld. I would get the mill data on the pipe and trace back to why a bullet proof weld failed. This had to be a manufacturing defect that could have affected the entire mill run.

David
 
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It is a new installation of offshore material and I think regular schedule 40 pipe. All certificates were in place. It was to be tested to 140 psi and the seam failed at less than 80. According to the specs the original material was to be tested to 1400 psi...

Dik
 
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Sorry... forgot to add the material... carbon steel...
 
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Hi dik

I would recommend that somebody check the design before re-testing and make sure the pipe wall is thick enough for the application.
Also I would be in contact with the pipe supplier particulary if the pipe failed at a pressure it should have withstood.
I know that in some pressure vessel specifications that some welds are restricted as to how close they can be to a main seam weld but I am not familiar with ASTM

desertfox
 
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80psi?? and then cracked.
You are sure it wasn't made of bubblegum?

Greetings
 
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What exactly does the failure look like? Is it a hairline crack or did the joint open up?

How long is the failure?

What is the ASTM designation of this pipe?
 
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dik...along the lines of the last post, but more on the face of the ERW failure face. Was there lack of fusion? Was there a cupping pullout from one side or the other? Was there complete joint fusion? I've seen ERW pipe "unzip" in pressure tests, due to poor weld. Relatively rare, but it happens.

The 1"-rule makes no sense. ERW pipe can and is routinely welded...wherever necessary for the connections.

There is a 1" proximity reduction in allowable stress for welded aluminum, but not carbon steel.
 
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In all likelyhood the failure was in the H.A.Z. and not directly at the seam which is probably stronger than the pipe material.
 
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The pipe was 10" dia, sched 40 and the split was a few inches at the ERW joint.

ASTM A53, states:

12.2.2 Type S pipe and the parent metal of Type E pipe, except within 1?2 in. [13 mm] of the fusion line of the electric-resistance-weld seam, are permitted to be repaired in accordance with the welding provisions of 12.5. Repair welding of Type F pipe and the weld seam of Type E pipe is prohibited.
 
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There were two failures, an 8" one that failed at 125 psi and the 10" one that failed at 80 psi. Both from the same Chinese offshore manufacturer.

Dik
 
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To be frank - I wouldn't both repairing the pipe - I would flat out replace it and negotiate/demand restitution from the supplier - because that is not properly specified A53 pipe!! The pipe, to meet specfication approval SHOULD have been already tested by THE MANUFACTURER to -

8" Sch. 40 Grade A: 1340 psi !!!!!!
Grade B: 1570 psi !!!!!!

10" Sch 40 Grade A: 1220 psi !!!!!!
Grade B: 1430 psi !!!!!2

I don't have access to the ASTM standards right now, but I am looking at the ASME SA-53, which is identical to the ASTM except for insertion of test practices in 11.1.1 and editorial correction to Table X4.1

And there is no mention of the clause you have stated , in fact - it states "14.5 Weld repair shall be permitted only subject to approval of the purchaser and in accordance with Specification A 530/A 530M."
 
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Both from the same Chinese offshore manufacturer... say no more. I have never seen new pipe fail at such a low pressure, 80 psi, that is ridiculous. I have seen some ERW failures during hydrotest in the weld, most are due to lack of fusion, others porosity if the weld was really poor. I have also seen hook cracks fail. I don't know if your pipeline is liquid and will cycle, but if it does, defects like this in welds can grow from fatigue and fail later. I would be very weary considering these failed at such a low pressure, they must be very large defects.
I would not attempt to repair the weld but put in a new spool piece where the failures were.
I would seek some compensation from manufacturer.
 
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dik...

Can you get pictures and post them...???

They might be very informative and enable you ( and us) to learn more...

"brimmer" is spot on...... you have been sold un-inspected Chinese "crap pipe" and deserve compensation.

Now ... lets all repeat that new millenia business mantra:

"freemarkets....freemarkets....freemarkets...freemarkets.."

This fine forum has many other previous posts about defective Chinese piping, pressure vessels and components.

-MJC

 
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Chicopee:

I don't know where the actual failure was, but was in the same line as the ERW joint. See note to MJC

MJC:

No pix... the pipe was re-welded prior to us being informed.

AllHandlesTaken:

My quote from A53 was a direct 'cut and paste'; if you cannot locate this, has this been changed?
 
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I will have to check the ASTM standard later for that clause (or just take your word for it).

Like I mentioned I was looking at the ASME SA-53; 2007 ed.

What year is the ASTM spec that you are looking at?
 
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Whoops - I just noted that the clause you specified is in fact in the 2007 ASME SA-53; under 14.2.2 (I guess I should have looked a little harder :(

Regardless, I would still replace it all with different QUALITY pipe and take it up with your purchaser's/supplier.
 
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AllHandlesTaken...

I will have to check the ASTM standard later for that clause (or just take your word for it).

I see you've caught my posts before... if I don't like a standard... I make one up and give it a number <G>.

Dik
 
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