Accepting/Rejecting material substitutions in boiler
Accepting/Rejecting material substitutions in boiler
(OP)
Hi can anyone help me with this topic?
When we envisage boiler materials, material procurement will come back offering a substitute material.
For example, SA515GR70 instead of SA516Gr70. SA240TP304 against SA240TP310S etc etc
My question is
1) What are the critical factors to look for while accepting/rejecting such cases?
2) Mostly both these materials have Min Tensile strength, Yield Strength, Max allowable temp range etc are same.
3) So is it only required to see, the stress values at design temperature ?
4) What about material composition? Carbon, Cr, Ni contents etc too vary. How to evaluate a situation like this?
When we envisage boiler materials, material procurement will come back offering a substitute material.
For example, SA515GR70 instead of SA516Gr70. SA240TP304 against SA240TP310S etc etc
My question is
1) What are the critical factors to look for while accepting/rejecting such cases?
2) Mostly both these materials have Min Tensile strength, Yield Strength, Max allowable temp range etc are same.
3) So is it only required to see, the stress values at design temperature ?
4) What about material composition? Carbon, Cr, Ni contents etc too vary. How to evaluate a situation like this?





RE: Accepting/Rejecting material substitutions in boiler
In some cases, it is simply a matter of using material with equal yield strength, allowable stress, toughness, corrosion resistance, etc.
In some cases, especially with the stainless steels and other alloys, the designer may have been trying to solve very specific corrosion or welding issues, where they know that using X material welded in Y procedure is resistant to a particular product in a particular service, etc.
RE: Accepting/Rejecting material substitutions in boiler
One has to see if the proposed original vs suggested substitution materials meet requirements of ASME Sec-II, Part-D, with respect to allowable stress , and also the service environments. You may read clause PG-5(5.1....5.5) for further clarifications.
Thanks.
Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario, Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299
RE: Accepting/Rejecting material substitutions in boiler