Gasket for Hydrotest 1

[H Cameron]

Hi Guys,

I am going to manufacture an item which shall be supplied with 300# spiral wound gasket.

As I know I have to change the gasket after hydro test and supply the item with a new gasket. can I do the hydrotest with a flat ring gasket 300# instead of spiral wound?

Thanks

 

[DSB123]

I do not think there is a problem with that.

 

[SnTMan]

H Cameron, why can you not hydro with the service gaskets? Done all the time.

Regards, Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[H Cameron]

Hi SnTMan

just because of availability in the stock and less price.

Thanks

 

[LittleInch]

A lot of the issues about gaskets, their re-use and otherwise were discussed in this thread very recently. Some good reference material included further down the thread.

http://www.eng-tips.com/viewthread.cfm?qid=415616

I think what SnTman is saying is re-use the gaskets... If you don't break the flange after hydrotest then I would agree, but if you do then it should, officially, be a new one according to all the vendors. I tend to agree as most spiral wound gaskets will plastically deform when used so will never be the same again second time around.

In summary you can hydrotest with a piece of paper if it will seal the joint OK. Tendency with poorly sealing gaskets is to over tighten the flange so make sure you don't over torque it. If it still leaks, take it off, clean it, new gasket and try again.

A few times of doing that and using spiral wound and then ditching them makes sense.

I've seen shops store old spiral wounds for testing only, but wouldn't recommend that myself.

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

 

[SnTMan]

LittleInch, I was talking more about not breaking the joint. Ideally, any joint broken after hydro anytime should get a new gasket.

Sometimes a client spec will not permit hydro w/ service gaskets, in that case you do replace them after hydro and normally perform a low pressure air-test to prove the newly made joints.

And yeah, it's not that uncommon for SW and even sheet gaskets to be re-used for hydro a few times.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[LittleInch]

SNt - It's wasn't clear whether the flanges were being broken or not, but why anyone would want to change gaskets after hydro just for the sake of it I don't know.

And Yes, its any time you break the flange - agree 100%

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

 

[SnTMan]

LittleInch, body flanges? One nozzle flange? A hundred? I really don't know what we're talking about either

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

Please, see ASME PCC-1

6 INSTALLATION OF GASKET
Place a new gasket in position after determining the
absence of (or having made correction for) unacceptable
gasket sealing surface imperfections and flatness tolerance
deviations, as well as joint alignment considerations
(see Appendices D and E).

Reuse of a gasket is not recommended. However, the
substrates of grooved metal gaskets with facing layers
may be reused after having been reconditioned and
refaced in a manner consistent with the original product
specification. The reinstallation of gaskets so refurbished
is not considered gasket reuse since the sealing performance
of the gasket has been restored. For other gasket
types, experience has clearly shown that only a new
gasket will reliably provide the necessary plastic deformation
and elastic recovery characteristics essential to
achieve an effective seal. Visual or physical inspection
of a used gasket for apparent damage is not sufficient
to detect such sealing surface factors as work-hardening,
brittleness, or the effects of heat or interaction with the
service fluid.

Regards
r6155

 

[GenB]

Yes you can test and replace. If you have to replace for the spiral W. Gasket why not test with the Spiral W gasket and leave it at n place.
Because if after the customer receives the vessel leaks for any reason you will be in trouble.