A36 for Membrane Wall of Boiler

[Shofa]

Gents,

Is SA 36 could be using for membrane wall between tubes for boilers ?! If not, why and what is the recommend material to be using.

Sincerely,

Shofa

 

[metengr]

Yes, it can be used as membrane material. The Code (ASME B&PV) allows for any weldable grade of material to be used as non-pressure part material as long as you have traceability and it can be welded (less than 0.35% C).

 

[deanc]

If the specs. allow it,flat bar is easier to work with than sheared plate.

 

[Shofa]

Thanks for your feedback.

 

[Shofa]

metengr;

Regarding using SA36 for ASME I equipment, i noticed that in thread No. 154527, your reply was as the following:-

Question 2Quote:
Can it it be used as metal backing on welds for pressure parts?
in a Sec I Fired or unfired?

Reply; No. If you review PW-5.1 of Section I, Part UW, it states that materials used in welded construction shall conform to one of the material specifications in Section II with allowable stress values. Well, SA 36 does have allowable stress values but you must read further that Section I limits the use of SA-36 to bar stock and for use as stays - See Section II, Part D notes G15, G18.;


I think there is a conflict between your repy at the top of this thread and your reply in the other one. Could you please explain to me.

I will repeat my question again.

Can A36 use as membrane wall (Non-pressure part) which will be welded to the wall tube (Pressure Part) in the boiler, although it is not permitted to be using for ASME I in accordance with ASME II Section D. Please advice.

for your information, the metal temperature could be around 400°C.

Regards,

Shofa

 

[metengr]

Shofa;
There is no conflict. Metal backing used for pressure welds is subject to pressure because it is considered an integral part of the weld. Therefore, it is pressure retaining.

Non-pressure part attachment material that is fillet or seal welded to pressure parts, is what it is, this includes external attachments, membrane material, etc.

 

[GenB]

metengr
How come most boiler mfrs use A36 as back-up bars,
I still do not understand the ASME I mentality of not allowing A36 but for bar-stays only(pressure parts)and not only that; it is limited to 650F.
Questio: Do you know any suppliers of SA675 bar? which is allowed for >650f.
genb

 

[metengr]

GenB;
As you mentioned, the maximum permitted service temperature for A 36 in Section I application is 650 deg F because this is the maximum temperature where time independent properties govern allowable stress values. Above the 650 deg F temperature, time dependent properties like creep or stress rupture control allowable stresses. Given the variability in grain structure for A36, my best guess is that it is unpredictable for ASME B&PV Section I for primary membrane stress applications.