Heat-treated and internally hardened for high durability; available in various materials to meet a wide range of applications; standard one or two-piece configuration, with designs available for pressure of 5000psi(35.1Mpa),  7500psi(52.7Mpa), and 10000psi(70.3Mpa); discharge connections available on each side; suction connections on each side or front center.

Material is 35CrMoA or 40CrMoMn alloy forged steel. To get better fiber texture, we use electric stove for second forging, or deoxidation treatment. It is forged from three directions and the forging ratio is not less than 4.0:1.0. It can not have crack, impurity, looseness, overburn, etc. And weld is not allowed. It should be confirming to the stipulation of JB/TQ252-81, and should be checked by gradeⅢ After quenching the rough module will be rough processed, then the hull hardness is HB285-330.

Mechanical property: σb ≥850MPa, σs≥670MPa, δ≥5%,ψ≥30%.

The two1:6(1:12) taper hole rolling treatments are checked by ring gage. Its contact area has continuous distribution on the circumference. The contact area is not less than 75% .The line of intersection of all cylindrical surface of the hull are facetted obtuse angle by hand or grinding wheel ,forming a circumference R≥8.Test pressure is 49Mpa, keep pressure 1 hour, pressure can not be reduced. Finished products have crack detection report.