... alloy steels, 2. 20CrMnTi, 20CrNiMo. The main material of Valve Assembly is high quality alloy steels,such as 20CrMnTi, 20CrNiMo.The ... Valve Insert was made by newly high molecular materials,to make the mud pump ... -temperature,high-pressure,anti-friction and sulfur corrosion. The valve assembly made by Dezhou Rundong Petroleum Machinery Co.,Ltd. ranks in the ...