SA-335 Grades

[Mech-Engineer]

Hello,

I am looking at a process which has a design temperature of 470 Deg. C (max operating temperature 450 Deg. C). Piping design code ASME B31.3. Fluid service is non-corrosive.

SA-335 P1 has been proposed as a suitable material. As far as I can see this material is acceptable as per code based on the service conditions. However referring to some piping handbooks, it seems that grade P1 is not that commonly used for piping in industry (I may be wrong on this?), with other alloy grades such as P11, P12, P22 being more common?

I would like to learn more about the selection process for a high temperature alloy and the differences in performance of P1 vs other similar high temperature alloys such as P11.

I’d also like to better understand the differences in terms of market availability, cost, constructibility.

Any tips would be appreciated.

 

[MJCronin]

The Long term Creep Failure history of SA-335 P1/P11/P22 is the real issue here .. The fact that the materials are noted in B31.1/B31.3 etc is immaterial ...

Google "SA-335 piping MJCronin eng-tips"

MJCronin
Sr. Process Engineer

 

[Mech-Engineer]

MJCronin - thank you for the response. I wasn’t able to find your earlier thread using this search. Would it be possible for you to send a link to this thread?

Given that the max. Operating temperature in this base is 450 C, as per my understanding this is below the creep temperature range, and so at this temperature would you see any concerns for SA-335 P1/P11/P22?

Any recommended further reading appreciated.

 

[Larry-MTS]

A335 P1 is 0.5Mo steel, in my opinion, is an outdated heat-resistant steel. Although I've seen some buying requirements for these steels, most pipe mills will not perform a production run unless the volume is huge (say more than 30 MT for each size). If the quantity is large enough, its price will be the lowest. By the way, the 0.5Mo (ASTM A182 F1) forged flanges can be readily sourced due to the availability of raw materials.

ASTM A335 P11 offers the best cost-performance ratio. The massive production of various 1.25Cr-0.5Mo materials makes it very economical. Due to the addition of chromium, improved oxidation resistance or corrosion resistance is obtained. P22 offers better corrosion resistance and creep strength due to increased Cr-Mo content.

According to B31.1, the maximum application temp for both P11 and P22 are 1100°F. However P22 can withstand higher allowable stress at a given elevated temperature.

Please refer to this technical literature:

http://www.pipingpipeline.com/astm-a335-p1-p11-p22-0-5mo-1-25cr-0-5mo-2-25cr-1mo.html

 

[EdStainless]

The mill that I worked for hadn't made P1 in years, and P11 was very common.
P22 is pickier to heat treat than P11.
If P11 would work then that would be a good choice.

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P.E. Metallurgy, consulting work welcomed

 

[XL83NL]

I've never worked with applications using carbon and low alloy (CS&LA) steels above 400-425 deg C (where one would stop using default CS gardes likes A106-B).
Just out of curiosity, if I need an LA for use above 450 °C (say 500 °C), would P11 be a good starting point from a temperature/metallurgical point of view? Corrosion and other damage mechanisms need to be considered carefully of course.

Huub
- You never get what you expect, you only get what you inspect.

 

[weldstan]

At 450 C and above P11 would be a good starting point provided corrosion service permits.

 

[Mech-Engineer]

Thank you to all for the responses to my original thread, much appreciated and very helpful. Regarding A335 P1, understand that the European equivalent material 16Mo3 has good availability. Interested in any feedback on 16Mo3 for EN standards application.

 

[XL83NL]

Thanks weldstan. Do you happen to know an equivalent European grade? Would that be 13CrMo4-5?

Huub
- You never get what you expect, you only get what you inspect.

 

[mrfailure]

Given the operating temperature, I wonder if graphitization might be an issue for your application in using P1. Though not too likely, graphitization is expected to occur at temperatures above 425 deg. C. Chrome-moly steels like P11 or P22 are not prone to this mechanism as the Cr ties up the carbides.

 

[weldstan]

It's a bit light on Cr; closer to a 1%Cr-1/2Mo alloy which is a common tube alloy and would likely be OK at 450C.