Selection of Gasket/Stud for SS#CS Flanges

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Bathula Raghuram (Mumbai - PIPING)

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May 27, 2008, 2:04:04 AM5/27/08

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Gasket selection mainly depend on Temperature and Pressure of the media, Corrosive nature and Criticality of the application

Since you are using 316 in place of A105, u may use the similar combination of gasket, studs used for a CS#CS joint in the same process stream (since design conditions are same), unless you have contractual requirements if any.

From: Zameer Mohammed [mailto:dreamth...@gmail.com]
Sent: Tuesday, May 27, 2008 10:47 AM
To: material...@googlegroups.com
Subject: SS & CS Flanges

Dear Friends,

We have 2 mating flanges, one is SS316 and another is A105. Can I connect SS Flange with CS Flange? In this case, what type of Gaskets, Stud Bolts & Nuts we can use?

For all other CS flanges we are using spiral wound gaskets.

Thank you,

Regards,

Sabir

Kannan....@linde-le.com

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May 27, 2008, 11:45:18 AM5/27/08

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Gasket selection which is quit a big subject is in addition to what Raghu has pointed out, also linked eitherway with flange selection and the type of facing etc. which does not have any fool proof solution and near perfect guidelines. Based on practical experience from the plants in operation the plant owners have defined thier own practice after experimenting with different rational options and in addition by the closing reports of various pilot plants. Which has been adapted by major engineering companies and is being passed on to other companies. Also everyone may be knowing that the weakest connection is a flange connection in a pipeline.

Coming to the situation of Zameer, is a default situation in any process plant. The BEP (Best engg. practice) would be to follow the worst case / stringent side of the piping class. In this case the SS flange side piping class definitions shall be applied. Also the contract docs. never define these common scenarios. The same applies to a piping of 300# is connected with a 150# rating piping. The 150# rating piping shall be welded with a 300# flange and bolted with the 300# rating piping on the other side.

I cannot envisage a situation where a equipment nozzle is SS and the connected piping is of CS material. If so pl. review with your process dept.

With regards,
Kannan

"Bathula Raghuram \(Mumbai - PIPING\)" <r.ba...@ticb.com>
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27/05/2008 08:04

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