Oval and octagonal O rings on RTJ flanges 1

[Abrabaracurxis]

when do you choose one or the other? whats the criteria?
thanks

 

[unclesyd]

This is alittle more information than you requested but the questions will come up if you use Ring Joint Flanges.

This is direct from Wolar Industrial Ring Joint Manufacturer

http://www.wolar.com/index1.html

The R-Type ring gasket can be ordered to two different profiles, oval or octagonal in cross-sections. Both types have identical pitch diameter as the flange groove they correspond to. These gaskets are used in pressures up to 10,000 PSI. The octagonal type has a higher sealing coefficient than the oval, therefore being the better gasket of the two. The oval type is the only gasket that will fit a bottom radiused groove. Flanges with flat bottom v-grooves will accept either style. Gaskets that have been torqued initiating a metal-to-metal seal should be discarded and not reused.

Although similar in style to the octagonal gaskets, the BX Series can only be used with 6BX flanges and 16BX hubs. BX-Gaskets have been designed for higher-pressure ratings starting at 5,000 lbs. and ending with 20,000 lbs. Pitch diameters on BX gaskets are slightly larger than the pitch diameter of the flange. This forces the gasket to initially seal on its outside angles and secondly seal with its inside angles as the flange is bolted down to respective torque settings. Gaskets that have been torqued initiating a metal-to-metal seal should be discarded and not reused

RX gaskets are designed for pressures up to 15,000 PSI. These gaskets are interchangeable with r-oval or r-octagonal rings used on API 6B flanges. RX types of gaskets are more costly than your standard oval or octagonal rings, therefore not as popular. RX type gaskets perform excellent in 6B flanged blowout preventer stacks, which requires the additional mass of the RX gasket to support the higher pressures with higher vibrations and heavier weights of these units. Gaskets that have been torqued initiating a metal-to-metal seal should be discarded and not reused.