Outer ring of spiral wound gasket

[MATEGRITY2009]

My questions is:

- What is an advantage of outer ring of spiral wound gasket other than centering on the flanged-joint.

- When in-service flange joint had shown severe corrosion attack on outer ring of gasket, What is the criteria to determine that this gasket is safe to continueous service.

Thank for any help...

 

[pennpiper]

My thoughts:
a) The "Outer Ring" question: This ring of a Spiral Wound gasket serves two purposes; first is to act as a centering device as you have noted, second is to act as a retention device to prevent gasket "Blow-out".

b) The Corrosion question:
- If the flanged joint has not been broken or disassembled but you observe corrosion of the ring chances are there is no risk but you may want to schedule it for replacement during the next Plant Shutdown.

- If you have disassembled the flanged joint for any reason you should never reuse any gasket. Always replace any used gasket with a new gasket.

- In either case, if corrosion is noted on the outer ring your maintenance group should determine why it is corroded. Was this; (1) the natural result of atmospheric conditions or; (2) was this the result of a leak or (3) was it due to something else? Appropriate solutions and action should be taken for all cases.