Antifriction device for a valve control shaft

DETAILED DESCRIPTION What is claimed is: 1.
An antifriction device for a valve which serves to regulate the flow of a fluid and especially to withstand high pressures and temperatures, comprising a hollow body to which the fluid inlet and outlet pipes are connected and in which is rotatably mounted a closure member connected to a control shaft having a part extending externally of said body through a packing gland seal, the shaft being provided at the level of the packing gland seal with an annular flange applied with interposition of a washer of creep-deformable material against an annular shoulder of the valve body which surrounds the control shaft, wherein a groove is formed in the periphery of said shaft opposite to said washer, said groove being adapted to receive the washer material after creep deformation of the same in response to high temperature or high pressure to which the valve is subjected, said groove limiting the amount of said creep-deformation.
2.
An antifriction device according to claim 1, the valve also comprising a half-shaft connecting the closure member to the body opposite to the control shaft, a part of the half-shaft extending through a packing gland seal, the half-shaft being provided at the level of its packing gland seal with an annular flange applied with interposition of a washer of creep-deformable material against an annular shoulder of the valve body which surrounds the half-shaft, wherein a groove is formed in the periphery of said half-shaft opposite to said washer, said groove being adapted to receive the washer material after creep deformation of the same.
3.
A device according to claim 1, wherein the height of the groove as measured parallel to the axis of the control shaft is at least equal to three-quarters of the thickness of the washer prior to creep deformation.
4.
A device according to claim 1, wherein the groove is a figure of revolution about the axis of the control shaft.
5.
A device according to claim 1, wherein the groove has a substantially U-shaped cross section in which the two arms of the U are at right angles to the axis of the control shaft and the bottom portion which is parallel to said axis is joined to each arm by means of an arcuate portion