Spiral wound gaskets for use with flat face flanges

[p6g2p6]

Hi. Does anyone know if it is acceptable to use spiral wound gaskets with flat face flanges? Is there any standard that covers this? I know that spiral wound gaskets are typically used for raised face flanges, however I'm wondering if I can get away with using a spiral wound gasket with an inner ring with a steel forged FF flange. Thanks in advance.

 

[LittleInch]

ASME B 16.5, Appendix B table B-1 and other sections seem to cover this and say no.

What are the flanges? Steel FF and ?

If both are steel why the FF?
What pressure rating?

"I'm wondering if I can get away with ..." is never a good start to a conversation about flanges and sealing. IMHO

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

Then our question becomes, "How fast can you run".

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

 

[p6g2p6]

Littleinch, this equipment was installed before my time, so I am not sure why a flat face SS flange was used. It is flanged to a SS lugged butterfly valve.
I will take a read through of appendix B.

 

[GBTorpenhow]

SPW is fine for two flat faced forged steel flanges but flat faced to a lugged valve is a different animal, take a closer look.

What pressure class? What kind of butterfly valve? What's the originally installed gasket? What type of facing on the valve? What's the bolting material?

 

[gwalkerb]

LittleInch, how are you reading Table B-1 as prohibiting this usage? A spiral wound gasket falls into group Ib, but those gasket categories aren't used anywhere else. Following the references in Appendix B, it takes us back to B16.5 5.4, and 5.4.1 states that 'The user is responsible for selection of gasket materials that will withstand the expected bolt loading without injurious crushing and that are suitable for the service conditions.' It leaves the bulk of the responsibility up to the user.

While this would certainly prohibit the usage of SWGs with FF cast flanges (e.g. B16.1 CL125 or CL250), if the flanges in question are stainless steel, then they wouldn't be B16.1. As far as I'm aware, all stainless steel flanges in the ASME world would need to be either B16.5, B16.47, or something custom with Section VIII Div 1 Appendix 2 calcs. I don't think there's enough information to be confident in a conclusion either way. Mostly it comes down to the butterfly valve - if the flange is a stainless steel machined B16.5 RF flange, I don't see any concerns on that side of the joint.

 

[LittleInch]

Gwalkerb,

When I wrote my response, all we knew was that there was one FF flange of "steel". Nothing about the other flange. Even now we don't know what its facing is. In all likelihood, this was originally a FF cast iron valve which has now been replaced by a Stl stl valve, But WE DON'T KNOW. We also don't know what was there before as it appears to be an existing arrangement.

Using a conservative approach the section in ASME B 16.5 2017 (my latest version), section 5.3.5 (Cast Iron flanges) recommends using those gaskets in section 1a of table b-1. This is where the sections in that table refer back to, not section 5.4.

So yes, a SPW gasket could work in these circumstances, but it's still not clear why a gasket from group 1a can't be used as is standard on FF flanges. Why change what's worked for decades?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[p6g2p6]

Thank you for the responses. The piping, flanges and valves were all replaced at the same time. I'm not sure what gaskets are in there right now and unfortunately the site is not accessible for the next couple months. The reason I was looking into spiral wound gaskets was because it was requested by one of the supervisors, however I don't think they realized they were flat face flanges at the time (neither did I until I looked more closely at the drawing). Given that there is no clear answer or recommendation in any of the drawings, I'm going to look more into using a group 1a gasket like Littleinch suggested. I appreciate the responses.

 

[TugboatEng]

Is this an externally corrosive environment such a marine? If that is the case you will want to use full face gaskets with flat faced flanges to prevent corrosion between the flanges.

 

[geesaman.d]

I design equipment that mount on tank shell manways. The tanks generally start with a flat face gasket and flat blank flange. But sometimes the tanks have 24" or 30" RFWN flanges and they don't like the cost adder for us to include the thickness on our adapter plate, and will try to pretend it's no big deal.

Any time someone suggests putting raised face gasket or raised face flange against a flat faced flange I will have nothing to do with it. Flat face flanges are generally much thinner and can bend under the raised face bolting load.

For sure, a gasket and flange engineering exercise could show the acceptability but that's yet to happen. In my world this is just people being sloppy / lazy / inexperienced / cheap and hoping I'll supply my stuff such that the ownership would transfer onto me. Nope, not doing that.

 

[Daren Samy]

ASME 16.20 accomodates using SWGs for raised face flanges. As per OE, In case of corrosive media, don't use it.

Daren!