Mud Pump Pistons are made of high hardness alloy steel, and they are wear-resistant, anti-corrosive and anti-distortion after heat treatment. The seal of the piston can be made of polyurethane, polyether material and it can be also made of thiakol rubber. Type: Bonded pistons, Replaceable pistons Material of piston hub: forged by 45# steel or 40Cr with hardening and tempering Material of piston cup: urethane NBR rubber Surface treatment of piston hub: by phosphating and by Oxidizing Size: 3 ~ 8 in Brand: NATIONAL, GD, EMSCO, OILWELL, IDECO, DRILLMEC, WEATHERFORD, BOMCO, TSC, EWCO, AMERICAN BLOCK, EWECO, HONGHUA, LS NOV, WIRTH, RONGSHENG