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Question:

I have always been told that the X in BX or RX meant pressure energized and that this feature increased sealing with higher wellbore pressure. Your literature tends to say it is energized by make up that creates coining and intimate contact. Please, could you clarify this for me?

Answer:

We have never found a person who would say that he knew definitely that X meant anything but that the flanges and ring gaskets that carry that designation where introduced later, as extra flanges to the original 6B flanges specified by API.

RX ring gaskets have specific design incorporating a pressure energized feature. However to seal, they must coin on their O.D. sealing surface in order to have intimate contact sufficient to prevent leakage. With intimate contact achieved by coining, the pressure inside the sealed system will further energize the gasket by pushing it outwardly against this coined surface. The RX asymmetrical design forces the majority of coining to the O.D. of the ring gasket by having wide flanks on the I.D. of the gasket and narrow flanks on the O.D. Leakage passed the I.D. flanks of the gasket brings additional pressure against the already coined and compressed O.D. flanks, further aiding the seal.

BX gasket specifications seem to imply that these gaskets have a self energizing feature, but if they really do it comes from the fact that BX ring gaskets have a pitch diameter greater than the groove they fit into. This greater diameter causes the gasket to compress or reduce in diameter as the flanges pull together with the bolt force. This compression or diameter reduction stays within the elastic modulus of the ring gasket, so that the compressed and coined BX ring gasket remains constantly energized against its coined O.D. surfaces. Once achieving a seal in this manner, internal pressure just adds to the force against the coined sealing surfaces.

We offer more information and illustrations on this website that we hope make this explanation clear:
see http://www.woodcousa.com/field_appr.htm.

For a Catalog for Bolts, Nuts, Ring Gaskets and Wrenches, Click Here.

Information above, and in other parts of this Web Site, may help persons who really seek to know. If you have a question, and you think WOODCO USA may have the capacity to answer it, please use our link and give us a chance to help.

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