FRP to CS flange connection

Dear all,

Could you please help me with the problem below.

FRP flange is connected to CS Flange- (DN 2200 -5bar-ASA 150 drilling)

The Flange is connecting the FRP cooling water pipelines to carbon steel Header.

The inside diameter of the carbon steel flange (ID=2291) is larger than the inside diameter of the GRP flange(ID=2200).

The GRP Flange was intended to be sealed with an O-ring (mean dia of oring groove= 2282mm, Dia of O ring 42mm) assuming that the ID of the CS to be same as that of FRP.

Since the ID of the CS flange is 2291mm, the O-ring could not function.

Hence the contractor installed a rubber gasket seal instead of the O-ring.

Wrinkles & displacement of installed gasket seal were noted on inspection- may be the result of over torqueing/ not following tightening sequence

The joint is likely to fail in Hydrotest

- Any solution for above-??

I have a couple questions:
1) ...Is this a full face rubber gasket with holes for stud-nuts? ...What thickness?
2) ...The C.Stl. flange is flat faced or raised face?

GRP is very manufacturer specific, especially with the large size fittings; so I suggest that you raise this query to the GRP manufacturer / supplier.

Hi

11echo,

1) ...Is this a full face rubber gasket with holes for stud-nuts? ...What thickness?

Yes Its full face with apprx 8 mm thickness

2) ...The C.Stl. flange is flat faced or raised face?

CS flange is flat faced

gpsvn,

Thanks for your suggestion.

--

Happy New Year to all

anil1729 ...Well I'd say your "half way home" on this one! The only other thing I'd do is machine the FRP flange to a flat face configuration and you would have a near perfect bolt up! After the machining effort you'll probably have some of the o-ring groove left, but the overall surface contact would more then make up for it, and you should be fine.
NOW this is the way we would do it in the oil fields, but this maybe a different issue in a facility where piping spec.s and code are rigidly adhered too. I'm guessing this is not an issue for you because of the situation your in now. My $0.02 anyway GOOD LUCK!!