Quench & Tempering Material to Yield Better Properties

[fabineer]

My company has a request from our customer to quench and temper a small vessel made of 410SS. They would like to do this to be able to take credit for better material properties to be used in ASME Code calculations. I believe there is a section of the code that deals with being able to use upgraded properties like this but I haven't found it. Can anyone point me in the right direction?

Also, what guidance does the code give regarding recertifying a material to another, "better for the application" grade if we (a company other than the mill) perform such things as Q&T?

Thanks for any help.

 

[weldtek]

Suggest you discuss this with your AI.

 

[metengr]

First, the list of material permitted by Section VIII, Div 1 is SA 240 410 SS. The minimum YS is 30 Ksi and UTS is 65 Ksi. You cannot fall below the minimum values for tempering. Is the vessel completed? Has it been code stamped (Section VIII, Div 1)? If so, this cannot be done under ASME code rules.

If the material has been procured prior to completion and has not been welded or fabricated, you can quench and temper the 410 material to a specific strength level. Additional testing will be necessary to ensure compliance with SA 240.

 

[fabineer]

If the material has been procured prior to completion and has not been welded or fabricated, you can quench and temper the 410 material to a specific strength level.

We have the unwelded material and have not begun working on the vessel. What do you mean by "you can quench and temper the 410 material to a specific strength level."?

Also,where does the code say this is allowable? I apologize for the elementary questions regarding this process; it is not something I have dealt with before and am trying to gain a little understanding.

Thanks again.

 

[metengr]

The Code does not provide guidance on every manufacturing aspect. It provides guidance for material and associated specifications to use for pressure vessels.

You probably have procured SA 240 Type 410 stainless steel plate. The question is can you temper the material further to remain above the minimum tensile properties and give you margin for toughness. Another options is to have a separate heat treatment performed (Quench and Temper) and re-certify the material to SA 240 by mechanical testing. These options all depend on what you have in your Quality Manual as an ASME Certificate Holder and approval from the AI.