ASTM A369 Grade FP22

[denil]

Dear All,

In our spec. for VHS requirement (Press.=117 Barg, Temp.=519 deg. C), we need heavy wall thickness pipe Forged & Bored, BE, ASME B36.10M, ASTM A369 Grade FP22, with thickness and size :
* NPS 30" , thickness = 63.5 mm
* NPS 36" , thickness = 76.2 mm

There is one Bidder who was offering us an option as below :
* Pipe EFW, ASTM A691 Grade 2-1/4 Cr, Class 22 (welded pipe with sress relieved)with thickness tolerance +/- 0.3 mm.

Anybody can help me, is it technically acceptable or not ?
I have read the ASTM A691 standard. It clearly mentioned that thickness cover up to 75 mm only.
Is there any other requirement if we accept this offered material ?
Please give me suggestion and explanation.

Thanks and regards,

Denil

 

[metengr]

No, it is not acceptable in my opinion. The ASTM A 691 specification is for seam welded pipe, and is not acceptable if you specified seamless pipe under the ASTM A369 specification.

I would only use seam welded pipe if you are below the time dependent allowable stress values for this material. In this case, the service temperature should be below 482 deg C. Since your service temperature is 512 deg C, I would not recommend seam welded pipe.

Try A 335 Grade P22.

 

[EdStainless]

If you go back to the ASME specs you will find that you are restricted with the welded material. It can be used, but the stress limits are lower. As it recall the welds are OK, it is the HAZ that has creep issues.

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[metengr]

ASME B&PV Code Section I does NOT permit the use of seam welded pipe in construction. AS I stated above, these are NOT equivalent materials and should not be treated as such.

I addition, by introducing a seam weld, you will need to monitor this pipe material for in-service creep damage over time. This cost must be added to your selection of using welded pipe.

ASME B&PV Code does not currently permit the use of seam welded pipe in construction. However, this will be changing with the introduction of hefty penalty factors to current allowable stresses. For this case, you might see a factor of 50% meaning the pipe will become twice as thick to provide for adequate creep design margin.

 

[denil]

Thank you metengr,

Your suggestion and explanation are highly apreciated.
We would like not to accept of welded pipe option offered by that Bidder.

Thanks and regards,

Denil

 

[davefitz]

sa 691 , classes 40 and 41, are N+T or N+Q, not simply stress releived. If teh vendor is selecting SA 691, then you should select the N+T or N+Q option, as this will repair the HAZ defects and returnt he HAZ to parent properties. But only if SA 691 meeets the design code for the application.


If the SA 691 option selected is only stress releif, then everything Meteng stated is correct, and a weld creep strength reduct factor of about 0.75 would need to be applied and longitudinal weld creep monitoring device be added.

There is to be presented a paper by a japanese author at this week's EPRI Fla confernece on advanced alloys that presents their lab results of the HAZ property restoration that occurs with N+T. I understand the ASME committees are under pressure to approve SA 691 for sect I and B31.1 service.