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POSSIBLE FAILURE OF SS FLANGES DUE TO USE OF B7 STUDS

USE OF ASTM A193 GR B7 STUDS IN SS316L PIPING SYSTEM. I HEARD THAT IT IS ADVISABLE NOT TO USE ASTM A193 GR. B7 STUDS FOR SS-316L PIPING SYSTEMS TO AVOID CARBON PICK UP BY THE FLANGES WHICH ARE IN CONTACT WITH B7 BOLTS. IT IS ADVISABLE TO USE ASTM A193 GR B8 STUDS. ARE THE ABOVE STATEMENTS TRUE. CAN I GET EXPLANATION FOR ABOVE STATEMENTS.

RAJA SHEKAR K
INSPECTION ENGINEER IN REFINERY - MUMBAI, MAHARASHTRA, India
2004

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Dear Mr Raja Shekar,

I have no idea what you mean by B7 Studs; but if they are made of High Carbon steel and your flanges are made of SS then the information you have may be phrased in a complicated way as I do not know what you mean by carbon pick up, I can only think of corrosion and failure of your fastener. If Carbon on your flange affects what inside your pipe, then we are talking about another matter.

I have zinc-iron plated flanges used in refinery heavy water pipes and have not received any complaints. An alloy plating like zinc-iron lies almost inert next to SS without corrosion.

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2004

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Using b7 studs on stainless steel flanges is not recommended due to the carbon steel embedment into the stainless. also the B7 will rust whereas the stainless will not. the common practice is to use stainless hardware with stainless steel flanges

Jim Darby
- Providence, Rhode Island, USA
September 25, 2009

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