Welding Root Pass VT NDE of Value? 2

[PipeLayer15]

I am working for a mechanical contractor that is constructing B31.1 power piping. Butt welds, max 16" sch40 pipe (majority <8"), design P/T of 232psig @ 250'F.

Owner's specification is asking for 20% VT examination of all root passes and 100% RT examination of all completed welds.

What is the value in completing the root pass examination? Is there any value to the owner that we would be asking them to concede if we request to have the root pass examination waived and/or removed from the contract by change order?

If it matters, the welder is very competent and has a very low failure rate. Assumed that the only value proposition to the contractor is to catch something on the root pass inspection and deal without before completing the weld and incurring the RT cost. This is of low concern to us.

Industry feedback is greatly appreciated.

 

[gtaw]

Your last sentence says it all. It may be of low consequence to you, but not to the owner. Since the NDE was in the bid package, the owner assumes you factored it into your quote. He is willing to pay the extra cost.. Why are you trying to change the rules of the game after the fact?


Best regards - Al

 

[DekDee]

Agree 100% with Al.
If the Client requests it and the requirement is in the purchase documentation then it is your responsibility to comply.
The fact you do not agree with the Clients request means diddly squat.
Cheers,
Shane

 

[weldstan]

It is assumed that the contractor or you have no welding inspectors on site and that is the real reason you do not want to comply with the Owners requirement. Too bad, hire a welding inspector to visually examine the welds.

 

[gtaw]

Don't forget the 100% RT.

Best regards - Al

 

[weldstan]

Haven't forgotten the 100% RT requirement. But as the former RT, MT, PT, VT Level III for my former construction company, I do not consider the subcontracted NDE company's RT Level II, to be a qualified welding inspector.

 

[PipeLayer15]

Yes, this is all about cost & TIME. It is not about cutting corners and delivering a code minimum product to increase profits. Project is already underway and root pass VT examinations are being completed. Any deviations from this will be done in the proper way. (RFI or similar).

The construction that we undertaking is very disruptive to the owner's ongoing operations. (eg. cut & cover road closures in a metropolitan area)

The current world pandemic has stretched resources and is going to potentially impact the owner's ability to continue on with tendering future projects as per their master plan. This is as much about our current project as is about finding ways to bring costs down in the interest of enabling future work.

We have an ongoing relationship with the owner, as part of this relationship the owner appreciates us pushing back against their separately contracted design consultants who have written the project's specification. We have requested our 3rd party NDE contractor to provide their professional opinion on the value of the root pass VTs, but their feedback needs to be viewed through the lens that this impacts their scope of work and potential contract value. (Similar to weldstan's feedback

Does the above additional background encourage anyone to actually provide feedback on what was asked (value of a VT root pass examination given that the weld will be RT) rather than question the motives of why it has been asked?

 

[weldstan]

At the pressure and temperature stated and under B31.1 for the schedule 40 carbon steel piping stated, RT is not required. I would consider them excessive. However, it is up to the client to determine whether it is excessive or not. I would have flagged the original contract during the bid phase and added costs of compliance versus B31.1. And if the client still persisted, we would charge them accordingly. Our standard practice would have been to visually examine about 10% of the root passes of each welder and 100% of the completed welds only in addition to the hydrostatic test.

 

[LJthien]

No doubt that Client pays what they requests such as inspection of root pass.

Client 's engineer may concern about root pass heat input and deposited weld thickness, which may cause cracking on large bore & long pipe.

We can always discuss Client if we imply somehow we meet their hidden requirements.

 

[weldstan]

In the nearly 40 power plants constructed during the last 20 years of my employment, I never saw such requirements for the piping described in the OP.

 

[gtaw]

The code specifies the minimum requirements. The Owner may go beyond the minimum requirements because of past experience, most likely not good experiences. Now he's taking the belts and suspenders approach to save future problems and grief. He also recognizes that the majority of the problems begin with the fit-up and root bead. Correct the little problem before it becomes the big problem.

What's the saying; "We might not have the time to do it right the first time, but we always make time to fix it the second time."

Best regards - Al

 

[Ishack]

As the name of the pass reflects the importance, The first pass is the root of your joint to keep them strength enough and it is directly experiencing the medium shocks and stress.

Ideally visual inspection cannot be substituted by RT as there are lot more indications can be found by VT which may not be able to by RT (due to the settings of RT, location, size of indications etc...).

Performing repair on the completed joint especially the root pass of the joint is actually worsening the joint integrity by introducing the uneven heat inputs and disturbing the whole welds even though you holds a qualified repair procedure.

This could be the reason owner wanted to implement such a specific requirement in order to minimize(of course cannot be avoided in the industry) the root repair after completion of weld.

The time plays a very important role and it is least advise that if you can prove the client that weld repair rate specially on the root (by both VT and RT) is very negligible, then perhaps owner may waive off if no other conditions are exist.

 

[Ishack]

As the name of the pass reflects the importance, The first pass is the root of your joint to keep them strength enough and it is directly experiencing the medium shocks and stress.

Ideally visual inspection cannot be substituted by RT as there are lot more indications can be found by VT which may not be able to by RT (due to the settings of RT, location, size of indications etc...).

Performing repair on the completed joint especially the root pass of the joint is actually worsening the joint integrity by introducing the uneven heat inputs and disturbing the whole welds even though you holds a qualified repair procedure.

This could be the reason owner wanted to implement such a specific requirement in order to minimize(of course cannot be avoided in the industry) the root repair after completion of weld.

The time plays a very important role and it is least advise that if you can prove the client that weld repair rate specially on the root (by both VT and RT) is very negligible, then perhaps owner may waive off if no other conditions are exist.