×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Natural Gas Gasket Type Recommendations???
2

Natural Gas Gasket Type Recommendations???

Natural Gas Gasket Type Recommendations???

(OP)
The pipe spec I'm using calls our Flexitallic (sp?) spiral wound gaskets for natural gas piping systems.

The gas supplier recommends using fiber gaskets.  I have no problem with following the supplier's recommendations, but we have an existing system with the spiral wound gaskets installed that's been in service about 5 years.  There has been some reports of flanges leaking, but there are no NDE reports on the system, so I don't know how well the system was installed.

There are two higher pressure systems --- one at 50# the other at 150#.

Recommendations?  Can I make the flexitallic gaskets work?

What should I specify for future?

Thanks!

RE: Natural Gas Gasket Type Recommendations???

Spiral wound (316 or 304 w/graphite filler) is the gasket of choice at 3 facilities I'm familiar (2 refineries & 1 natural gas compressor packager).  It should work fine.  Specifically what fiber gasket is the gas supplier recommending?

Are you the spec "owner?"  If not, don't just deviate without getting approval.

RE: Natural Gas Gasket Type Recommendations???

If a flexitallic is not sealing at the low pressures you are quoting, the operator has an installation problem.  I suggest you get on Flexitallics web site and download their recommend installation methods.

At 50# or even 150#, a fiber gasket is fine for clean natural gas.

RE: Natural Gas Gasket Type Recommendations???

I am currently reviewing piping specifications for a fortune 500 company
The specification depicts flexitallic stnls stl insert gasket for natural gas service

RE: Natural Gas Gasket Type Recommendations???

It's a wonder they get to stay a fortune 500 if they continue to over specify, oh well.....

RE: Natural Gas Gasket Type Recommendations???

I've used flexitallic gaskets in every service from  vacuum up to thousands of pounds.  They're forgiving, don't require gasket compound, and are easily installed (hard to install incorrectly).  

The only reason I can think of not to use them is in situations where the spacing is critical (like the side flange on an ejector) and the design calls for some other kind of gasket.  If the spacing is not critical I'll always use flexitallic gaskets.

David

RE: Natural Gas Gasket Type Recommendations???

2
UtilityLouie,

Most all refinery and chemical plants would use the spiral wound gasket - it is fire resistant.  The former asbestos sheet gaskets were also fire resistant.  Most of the fiber gaskets with elastomer binder will not be fire resistant.

Another item to be concerned with the fiber gasket versus spiral wound gasket would be the pipe flange and the bolt material.  Steel flanges are able to compress either gasket.  If there are cast iron plug valves, the cast iron has concerns of low strength.  Fiber sheet gaskets would seal with low bolt loads.  Spiral wound gaskets require more bolt loading that could crack cast iron flanges.  A controlled bolt torquing procedure with A307 B bolting might possibly seal a spiral wound gasket without cracking cast iron flanges, but is it worth the risk? Most refineries don't allow A307 B bolting in the plant, they are afraid low strength bolting would be installed where high strength B7 alloy bolts are required,  have a flange joint failure, and a fire.  

RE: Natural Gas Gasket Type Recommendations???

We have a wall full of every flexitallic we use as spares, and a little itty bitty corner for fiber.  We use the fiber on low pressure and specialty areas, it's nice sometimes to ball peen out a gasket, and cheep too.

RE: Natural Gas Gasket Type Recommendations???

Why does the gas supplier recommends fiber gaskets? as an experienced oil refinery maintenance man I recommend to go with flex gaskets for this application,they are very reliable  and maintenance friendly

RE: Natural Gas Gasket Type Recommendations???

In a class 150 piping system, your problem with spiral wound gaskets is more than likely low bolt load.  There are many sizes of class 150 flanges (especially NPS 3, 8 and 12)where even A193-B7 bolts will not develop sufficient compressive stress on a SW gasket- especially if it has an inner ring.

If your spec allows, switch to a non-asbestos fiber gasket.  Make sure to check the binder to make sure it's compatible- Nitrile binder would be best.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources