material selection

[Scott24]

Could someone tell me where I would check if materials are compatible with each other and what the governing factors are ie P No group No chemical make up in ASME VII ? appreciate this is a simple question but your experience and help is appreciated this is a learning process for me .

 

[XL83NL]

Could someone tell me where I would check if materials are compatible with each other

Compatible in what sense? Welding metallurgy? Galvanic corrosion? Mechanical properties? Availability?

and what the governing factors are ie P No group No chemical make up in ASME VII ?

You mean ASME VIII? The basis for P numbers (someone will correct me if I'm wrong here, but in general its like) a grouping of materials of the same chemical make and same mechanical characteristics.
What does the P-nr according to you, have to do with the original question?

appreciate this is a simple question but your experience and help is appreciated this is a learning process for me .

The answer could be simple if you had better defined your question.

 

[Scott24]

Reason for my question was that I want to clarify what parameters I have to check in order to see if materials are compatible and can be substituted for each other ie C715 FOR monel 400 plugs in a heat exchanger one has 30% nickel content other 60% how do I know if this is ok ?

 

[XL83NL]

Again;

how do I know if this is ok ? how do I know if this is ok ?

Ok for what (purpose)? Corrosion? Mechanical properties, e.g. yield or tensile stresses, thermal conductivity?

 

[weldstan]

Your materials are 70-30 Copper Nickel alloy and Monel (Nickel Copper) alloy. They can be welded together. What is the service environment (media, temperature, pressure, fluid velocity)?

 

[EdStainless]

You need to start by going back to the design information.
If you don't have the original design calculations then you will be hard pressed to justify a substitution.
These alloys are different in strength,temperature limits, corrosion resistance, thermal expansion.
If this is a low temperature, mildly stressed, non-corrosive application then the call is easy, otherwise there is design work involved.

P groups just mean that alloys are handled in a similar way for welding, it does not mean that they are interchangeable.

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Plymouth Tube

 

[metengr]

ASME B&PV Code Section IX committee developed a P-No grouping system to deal with various metals that exhibit similar weldability characteristics. This was only done to avoid having welding procedures for each metal or alloy. Weldability characteristics of metals having a similar P-No does not mean they are interchangeable for service.