Restrictions Related to the Use of ERW Pipe 2

[afstructures]

Hi,
I came across several steel material specifications which do not allow the usage of electrical resistance welded pipes.

Does anyone have an idea why?

I looked up the issue in API RP 2A, ISO 19902, DNV and Norsok and the only thing i found is that the tubular strength requirements are valid for ERW pipes only if they are heat treated to relief residual stresses after welding ... I don't know if this is a reason to avoid using all ERW pipes.

 

[MikeHalloran]

Offshore rigs are special. Because the hardware store is not right down the street, and time is more expensive than the best steel pipe, even gravity drain lines are made of sturdy stuff, because they may be scavenged for use in high pressure circuits. Nobody expects such a thing to happen, but nobody can guarantee that it won't be necessary.



Mike Halloran
Pembroke Pines, FL, USA

 

[afstructures]

MikeHalloran,

Many thanks for your reply.

So you beleive that it is the good old "Common Practice".

The problem is that our client has a stock of ERW pipes that they want to use in their new platform and asked for a justification for not allowing their usage.

 

[MikeHalloran]

The restriction may well appear in some API document; I'm not intimately familiar with them.

It's more likely to appear in a company's own written standards and practices, which in my limited experience are more strictly enforced, less flexible, and may contain the odd paragraph that makes no sense by itself but exists and is very strictly enforced as a result of a nominally small but very expensive lesson.



Mike Halloran
Pembroke Pines, FL, USA

 

[redpicker]

Years ago, the weld seam in ERW pipe had very low toughness and fracture of the weld seam was a common occurance, particularly under any torsional or combined loading. In addition, NDT of the weld seam was not very good. For these reasons, many applications simply forbade the use of ERW pipe.

Although great improvements have been made in the materials, processing, and inspection of ERW pipe, it is common of specifications that once a requirement gets written into them, it is nearly impossible to get it removed. It is highly possible that ERW pipe of today is more consistent in mechanical properties, had better toughness, even across the weld, and has better dimensional control than seamless pipe of 20 years ago, but this doesn't matter; it's ERW pipe and cannot be used.

rp

 

[BigInch]

ERW pipe made before the 1970s is from where the problem originates. Control of weld quality wasn't what it is now.
As the previous post says, there is pleanty of bad feelings still left over from the experience of a number of gas pipeline explosions over the years with the cause attributed to ERW welds, so some companies still may not allow its use, no matter when it was made, today.

We are more connected to everyone in the world than we've ever been before, except to the person sitting next to us. Lisa Gansky

 

[afstructures]

Thanks guys for all the replies.

I guess for the time decision the wise decision is to avoid using the ERW pipes, probably not many purchasers are asking for them in the market and you may end up limiting your vendor list.

 

[BigInch]

No, go ahead and request a quote. New ERW is OK.

We are more connected to everyone in the world than we've ever been before, except to the person sitting next to us. Lisa Gansky

 

[grampi1]

Our practice when considering stock ERW for offhsore pressure containing service is to have a third party inspection outfit double check the seam weld using UT to an N5 notch criteria. We also do two weld line charpy test sets per heat to verify weld has min API body toughness.

 

[afstructures]

I guess next time we can give it a try and see

Thanks guys for all your valuable input