Limit to rewelding monel 4

[ContractHome]

If a part was welded, the welds were machined down and the part was rewelded again, then how many time can this be done. I understand each time the welding and machining changes properties in the metal, other than visual inspection is there any limits to the number of times this can be done. I am many concerned with Monel 400 but would like to know if there is a test regardless of the material. Should a hardness or chemical analysis test be done. How would I unsure that I have changed an astm standard for the material, fitting or piping. Is there any ASTM, AWS or ASME specifications which limit the number of rewelds in the same area.

 

[metengr]

For this material there is no limit for re-welding, provided a qualified welding procedure was follwed and pre-and post weld nondestructive testing was performed using qualified personnel.

 

[EdStainless]

Since there is no hardening mechanism in M400 there is no real change in properties.
Machining down into sound material (even if it weld metal) will help assure that you get a solid repair.
Except,
1. There is a risk of contamination each time you weld.
2. The weld filler will be slightly different composition from the original material.

In metals where the heating and cooling will change the properties then you need to think about re-heat treating the parts after the repair.

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Plymouth Tube

 

[inspctr]

I know with P-91 you can only do a repair one time before it becomes too brittle and has to have a BRINNEL DONE AND THEN REMILLED TO SOFTER METAL, ABOUT 240 bRINNEL.

 

[ContractHome]

inspectr, can you provide me with the asme, astm or aws standard that requires the hardness testing.
Thanks

 

[metengr]

I know with P-91 you can only do a repair one time before it becomes too brittle and has to have a BRINNEL DONE AND THEN REMILLED TO SOFTER METAL, ABOUT 240 bRINNEL.

An absolutely incorrect statement regarding welding Grade 91 material.

 

[EdStainless]

If your weld repair does not meet the properties of the original spec then you have a problem.
There is no hard and fast rule on re-welding, but if you can tell then it is not acceptable.

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Plymouth Tube

 

[stanweld]

Thank you metengr for dispelling that myth. A star for you.