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Coating to prevent ACME Thread Gouging

2004

Hi all,

We are using ACME threads in our gate valve stems. The problem comes in some gate valves while closing, this is because of the line pressure exerted upwards. When I'm using a AISI 316 stem with NNR (Nodular Nickel Resist) D2[ ASTM a 439 D2 ] The hardess of NNR material will be around 40 BHN more than that of the austenitic SS. The thread we are using is a 4 TPI thread. Gouging is evident on the upper flank and the crust of the ACME thread. Can you suggest any coating to prevent this.

Karthik
Valve Manufacturer - Chennai, Tamil Nadu, India

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