Nozzle Reinforcement (MAWP or Design Pressure) 1

[lmacallndong]

Hello all.

Our customer's spec states that Vessel MAWP shall be the Design Pressure. Customer wants their vessel U-stamped and registered for MAWP = design pressure.

Customer spec also states that MAWP shall be limited by the lesser of shell, head or flange rating and in no case shall the MAWP be limited by the nozzle reinforcement. We clarified to customer that this clause is conflicting with their previous spec clause of MAWP=design pressure. Since they wanted MAWP=design pressure, there will be no limiting component. MAWP will be limited to design pressure. So for nozzle reinforcement calculations, we used the Design Pressure in UG-37 calcs.

On 1st & 2nd pass submittal of drawings and calculations, customer had no comments on nozzle reinforcement. Their comments superficial like add their logo on drawings. After submitting supposedly final issue of drawing, customer comes back and they want us to use calculated MAWP (limited by shell, head or flange) in nozzle reinforcement. This requirement would now make nozzle reinforcement limiting MAWP.

We are charging customer for reasonable price of re-order,redesign of nozzles and re-registration of vessel, but customer is insisting it is fabricator fault and they don't want to pay cost impact. Has any fabricator experienced similar stupid customer stupidities? Is this now a trend...stupid customers = $$$.

 

[jtseng123]

Never call your customer "stupid' publically or in the forum. It is unprofessional. They pay the $$, they are the boss. Be respectful. Otherwise, you won't get the next job and bad word spreads in light speed.
You will win the case but take time. If your customer won't pay, you shut down and don't deliver and you need a lawyer. Make sure you have all the email correspondences, minutes of meeting, etc.
You shall ask why they want MAWP by calculation now that is deviated from the original purchase order. You have their reason, that is the change, and change= cost impact. They pay for sure.

 

[rneill]

Normally, Client specifications have a conflict resolution process specified and if so, that process would define how to resolve conflicts in their requirements. If the conflict resolution process was not followed then they would be within their rights to require the change. If the process was followed then they have no grounds for asking you to change now. If no process was specified then it is very grey and it is difficult to take a position without seeing the actual customer specification and the specific wording used. Depending on the specific wording used, there may or may not have been a clear conflict in the original requirement.

Regardless, the best approach would have been to notify the client in writing of the potential conflict when you first noticed it and clearly seek their agreement on the way you proposed to resolve it. In this case, it would appear that you noticed the conflict but might not have made clear to them that by setting MAWP equal to design pressure (and no higher) that you would be in specific violation of another requirement of their specification.

 

[Leonardobetta]

Referring to the initial inquiry; i suggest the below steps to be followed inorder to clear such dispute:

1- During 1st & 2nd pass submittal phase; it is clearly indicating that afformentioned submittals are not finally approved/approved with comments. Thus submitted documents will be be further exposed to any new comments till you acheive final approved documents by your respective client. In this regards, comment coding system shall be clearly indicated in the client document control approval system.

(ex. Client comments code system; code a: approved, code b: work may proceed subject to incorporated comments, code c: Work may not proceed & document to be revised and resubmitted with incorporated comments...etc). By referring to the previously mentioned, you would have solid foundation for such dispute.

2-Contractual obligations w.r.t to documentations order of precedence which will clearly emphasize project requirements/codes/procedures order of procedence.

3-In the event above 2 pts. are valid, then cost impact will take place w.r.t your Subcontract Agreement relevant clause.


Hopefully, the above info will assist in clearing such disputes.

 

[gr2vessels]

Gents, my two cents.
The way I see the Client specification, he's asking for the most econonmical design, with minimal overdesign. That is the meaning of MAWP=design pressure. Further, the design of the nozzle must incorporate sufficient reinforcement as to not be the limiting factor, ie the MAWP for the nozzle to exceed some small percentage the design pressure and the shell MAWP.
I agree, the spec is very tight and almost impossible to achieve the MAWP=design pressure, simply because the standard plate thickness exceeds the minimum calculated thickness. That might push the nozzle reinforcement requirements even higher.
I think the way out is to include additional reinforcement to all nozzles and recalculate the MAWP, to confirm the Client's specification.
Cheers,
gr2vessels

 

[jamesl]

How about design the nozzle reinforcements to (DP + 1 psi)? This can be easily done by increasing some weld sizes. Then tell your client that the vessel MAWP is not limited by nozzle reinforcement, but limited by their spec.