Pipe union with both pre-load dependent and independent seals

A disconnectable pipe union comprising in combination first and second union members, an annular first seal for disposition between said union members, reusable means constructed and arranged to be placed under tension to draw said first and second union members toward each other for preloading said first seal therebetween, said union members being related to said first seal such that at least corresponding portions of said union members radially outward of said first seal remain separated axially with at least a certain minimum gap therebetween when the union members are drawn together with said first seal therebetween, and a second annular seal for disposition in said gap between said portions of said union members so as to surround concentrically said first seal, said second seal having opposite ends between which it is both contractible and extensible axially, and means for establishing a fluid-tight selectively separable connection between each of said first and second union members and the corresponding adjacent end of said second seal, said last mentioned means being operative independently of said reusable means, and said second seal being axially contractible to an extent sufficient to avoid interfering with the ability of said union members to be drawn together for developing fluid-tight interengagement with said first seal.

A disconnectable pipe union comprising in combination first and second union members, means for establishing between said union members a first circumferential seal whose sealing effectiveness is a function of its pre-loading and which is fluid-tight when pre-loaded above a given level, means constructed and arranged to be placed under tension to draw said first and second union members toward each other to provide at least at the time the pipe union is assembled at least said given level of pre-loading for said first seal, said union members being related to said means for establishing a first seal such that confronting circumferential portions of said union members radially displaced from the region of said first seal remain separated axially with at least a certain minimum gap therebetween when the union members are drawn together with said first seal established therebetween, and axially extensible tubular sealing means constructed and arranged for establishing a second fluid-tight circumferential seal bridging said gap and operative independently of said pre-loading, said axially extensible sealing means having axially spaced ends, at least one radially oriented corrugation located intermediate said spaced ends, and a rotatably orientable clamp ring mounted on one of said spaced ends for separably fastening said one end to the corresponding one of said union members.