Kelly valve

Claim 1

A pressure responsive kelly valve assembly comprising: a. an annular outer valve body member having a cylindrical interior surface; b. a flexible generally tubular and elastomeric annular inner valve body member disposed generally coaxially within said outer valve body member, said inner valve body member defining a passageway radially inwards thereof; c. means merging end portions of said outer and inner valve body members whereby an annular chamber is formed therebetween; d. a compressible gaseous control fluid disposed in said chamber, said control fluid being pressurized to extend said inner valve body member radially inwards to close said passageway upon the presence of fluid pressures below a predetermined release value in an area external to said chamber and axially adjacent said passageway, said control fluid further being compressible upon the presence of fluid pressures greater than or equal to said release value in such area to permit said inner valve body member to move radially outwards in response to such fluid pressures to open said passageway; e. a backup liner interposed between said outer and inner valve body members, with said backup liner having cylindrical exterior and interior surfaces having passage means for permitting flow of said control fluid to and from the liner interior and with said backup liner exterior surface being provided lands and grooves; f. said inner valve body further having annular flanged end portions shaped to conform with the end portions of said backup liner and bonded to end portions of the backup liner exterior surface; and g. said means merging end portions of said outer and inner valve body member being a means clamping said inner valve body annular flanged end portions between said backup liner end portions and said outer valve body member.