RX/BX API 6A ring gasket. self energized or non-self energized?

[yudhichen]

Dear folks,

I'm doing analysis for torque bolt requirement as mention on API 6A Annex D by using the formula from ASME VIII div2 clause 4.16.6 for design bolt load
As it come across to the gasket, ASME differentiates between self energize gasket and non-self energize.
I look around from other source, some said that API RX/BX ring gasket considered as self-energize gasket while others dont.
this determination was needed to know in order to define the gasket factor 'm' as depicted on ASME.

any idea about this?

Thanx

 

[Duwe6]

Google is our friend

Just found this;

"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.

Gaskets coin themselves (Blend In / Molds) to the surface finish of the groove, forming a custom surface seal. The vent hole on the BX Series through the gasket helps equalize pressures caught between the flange grooves. Gaskets that have been torqued initiating a metal-to-metal seal should be discarded and not reused"

If they 'crush' into the grooves, like the spiral-wound 'flex' ones do, they are not "Self-Energized". Elastomeric O-rings are self-energized; they don't seal properly until they see fluid pressure and are forced to the back of their groove by the fluid.

 

[ricklts]

yudhichen

Typically, API 6A requires bolt load equivalent to 55% of bolting Ys, while the same joint used subsea is spec'd at 75% YS applied load. A good source of m and y values can be found in one or more of the technical handbooks from a gasket manufacturer, such as Lamons or DanLoc.

Good luck,
Rick