package stuffing boxes improved alternative machines working under high pressure

摘要

A gland pack for reciprocating plunger machines operating at high pressure, comprising three-element seal assemblies housed in cavities at the head end of the pack, each element comprising a seal ring constructed of a self-lubricating plastics material and in the form of a number of pseudotangentially cut segments held together by a circumferential spring, which is coaxially sandwiched between two metal anti-extrusion rings which, when subjected to the high differential pressure of the working fluid, reduce their diameter until they approach the outer surface of the plunger but without ever pressing against it, the first metal anti-extrusion ring, which is situated at the head end of the cavity, being provided with radial grooves in its flat surface on the head side, whereas in the cavities at the crank mechanism end of the gland pack there are housed two-element seal assemblies, each element comprising a seal ring constructed of self-lubricating plastics material and in the form of a number of pseudotangentially cut segments held together by a circumferential spring and provided with radial grooves in its flat surface on the head side, and a metal anti-extrusion ring which, when subjected to the differential pressure of the working fluid, reduces its diameter until it approaches the outer surface of the plunger but without ever pushing against it; said metal anti-extrusion rings can also be in the form of a whole ring or in the form of radially cut segments held together by a circumferential spring.