Abstract
Piston-rod packing (sealing) rings are free to move radially in the cups and are given an axial clearance appropriate to the materials used. Sealing faces on the rings and cups are accurately ground or lapped. Case material can be cast iron, carbon steel, stainless steel, or bronze to suit the chemical conditions. It may be drilled to provide lubricant feed to the packing, to vent leakage gas, or to provide water cooling. The rings are held in contact with the rod by spring pressure; sealing action however, depends on gas forces that hold the rings radially in contact with the rod and axially against the next cup. There is no theoretical basis for determining the number of sealing rings. Rod material is chosen for strength or chemical resistance. Carbon, low alloy, and high chromium steels are suitable. For harder packings (lead bronze and cast iron), hardened rods should be used; treatment can be flame or induction hardening or nitriding. Chrome plating or high-chromium steel is used for chemical resistance.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
