We have a high temp valve that was
We have a high temp valve that was
(OP)
We have a high temp valve that was returned on warranty. Upon inspection the gate, stem, gate guides were all warped. Customer claims the operating temperature was 350 F but I suspect considerably higher. My question what temperature do you have to reach to discolor alloy steel (4130 Q&T) blue.





RE: We have a high temp valve that was
Warping can be due to any reasons -(1) residual stress from processing which got relieved in service, (2)mechanical overload ether during installation or service, etc.
Was it a welded structure?
Measure hardness of the area where it has discolored. If there is huge difference between the supplied valve hardness and warped material, it might have tempered more. Generally 4130 is suplied around 35-45HRC (25 for oil and gas applications due to SCC). See the microstrcure change, if any.
Refer to a heat treatment book where color change with temperature could be found. If everything fails, call your materials vendor for help.
I am sorry I can't think of any more.
RE: We have a high temp valve that was
RE: We have a high temp valve that was
RE: We have a high temp valve that was
Light Purple: 530° F
Full Purple: 540° F
Dark Purple: 550° F
Full Blue: 560° F
Dark Blue: 570° F
Light Blue: 640° F
If you need it, you might borrow a copy of Machinery's Handbook to see the rest of the table.
If you're the manufacturer, and have some parent material, you may wish to heat some of it (immersed in the media used in the value?) at increasing temperatures to see what temperature is required to duplicate the discoloration...
RE: We have a high temp valve that was