B31.4 Weld Inspection "Per Day" requirement 1

[PaperEngr]

Hello everyone,

Wondered if anyone had any experience with this:

B31.4 2016 Para. 434.8.5.3 states that above a hoop stress of 20% of yield, a minimum of 10% of girth welds "completed each day" are to be inspected.

What does this mean for large pipes where one girth weld takes most or all of a day to complete?
Inspect each and every weld? Or just inspect one every 10 days or so?

We have a lot of pipe 36" and larger, so the inspection rate being 10% or effectively 100% makes a big difference.

For your reference:
434.8.5 Required Inspection
(3) When the pipeline is to be operated at a hoop
stress of more than 20% of the specified minimum yield
strength of the pipe, the welds shall be inspected. A
minimum of 10% of the girth welds and 10% of the other
welds completed each day shall be randomly selected by
the operating company and nondestructively inspected.

Thanks in advance!

 

[1503-44]

It means that you need more welding stations and faster welders, or you need to reduce your design pressure and wall thickness.

It's a pipeline code so in all practicality the specification can be easily meet.
Nobody is going to build a 100 mile long pipeline at 41ft a day. That would take 34 years. If you can't weld 10 joints in a day and inspect 1, pack it up and go home before you go broke.

There are plenty of 36" pipelines out there, some a 1000 miles long and none took more than 2.5 years to build. I suspect you have a welding time error, or you need a new pipeline engineer that can design a system that can be constructed in less than 34 years.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[PaperEngr]

Appreciate the quick response. Will re-check what the fabricator is estimating for these welds.

 

[1503-44]

Sounds like a good idea.

Check these out first.

https://www.eng-tips.com/viewthread.cfm?qid=399448

https://www.eng-tips.com/viewthread.cfm?qid=478843

What is the wall thickness, diameter and material?

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[PaperEngr]

A lot of 36" - 48", 1" wall, API 5L-60.

Looking at the link for thick wall welds, the detail shows 10 passes using vertical welds for a 1" thick wall. On a 36" diameter pipe that's 3.1416*36*10 = 1131 inches of weld. Even at 100"/hr, that's a full day's work.

Which brings me back to the "per day" requirement in 31.4. Rereading it again, I don't see a requirement for a sample from each welder, which seems odd.

If that's correct, then you could have 20 welders finish one joint each, and pick two of them for inspection at the end of the day. That would meet the 10% inspection requirement.

If the inspection is per day AND per welder, then you're basically inspecting 100% of the welds, since it takes a whole day to finish one weld on the large pipe.

So would inspecting 2 out of the 20 welds meet Code?

Thanks in advance.

 

[1503-44]

Welders are QAQCd by routine welding proceedure qualification testing, apart from the daily pipeline welding inspection requirement.

2 out of 20 is 10% so yes that meets the Minimum requirement. It is common to do more than that inside pump and compression stations and crossing sensitive areas, which many are 100% NDT these days.

1" thick wall X60 will propably not be used outside the pump stations and other critical, or environmentally sensitive locations, offshore risers, or for other very high pressure, super strength purposes. It is too thick for routine cross country pipeline use. The 42" should be good for up to around 2160 psig, ANSI 900# Pressure limit, which is probably why it has not been used already. 2160 x 42" is one heck of a pipeline. There are not many pipelines that operate above 1460 psig. A 1200psig or even 1000 psig max are far more common. It just might be sitting around for a long long time before anybody asks for it.

Most cross-country pipelines will have walls in the range of- 1/4" - 5/16" - 3/8" - 7/16" - 1/2". Over 1/2" are not common.



A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[LittleInch]

PaperEngr,

You seem to be fixated on one welder doing one weld from root all the way through.

For pipelines of this size and any appreciable length, you would typically have one /two welders doing the root and hot pass, another two / three welders doing the filler runs and a third and final crew of two/ three doing the capping run on any particular weld.

So each weld is a mixture of welders and also you would definitely hope to do more than one weld per day....

Generally the choice of which weld to inspect by RT would be chosen by the welding inspector(s) and they would normally ensure that every welder or crew of welders is inspected on a regular basis within the 10% MINIMUM level required.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[PaperEngr]

Thank you all for the guidance.

Never had the opportunity to see pipeline being welded up. Having multiple welders working together explains a lot.

FYI these are not cross country. None more than a few miles. Can't say anymore than that.

 

[1503-44]

Didn't need to.
Very high pressure though. Even for short lines.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.

 

[LittleInch]

Depends on the DF. We've got some recently at 0.5DF so you can get pretty thick real fast.= for a DP of no more than 80 bar.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

He's reading 31.4 so that's 0,72 everywhere for pressure, so maybe the excess is for mechanical strength? No info on that.

A black swan to a turkey is a white swan to the butcher ... and to Boeing.