Bimetallic Liner – The Most Widely Used and Highest-Volume Fluid End Accessory for Drilling Mud Pumps

The bimetallic liner is currently the most extensively applied and largest-consumption fluid end component in drilling mud pump systems. It combines the advantages of a hot-forged, high-wear-resistant outer shell and a high-chromium, wear-resistant and corrosion-resistant inner sleeve.

The outer shell is formed by one-step hot pressing using high-quality carbon steel, while the inner sleeve is produced by centrifugal casting of high-chromium cast iron. The outer shell features a tensile strength exceeding 900,000 PSI. After heat treatment, the inner sleeve attains a hardness of HRC 62 or above, capable of withstanding mud pressures up to 7,000 PSI. Its internal surface is mirror-smooth, with stringent dimensional tolerance control on the bore diameter. Under normal operating conditions, the service life can reach 800 hours or more.

Material Specifications:

Outer Shell (Sleeve):

• Material: 45# forged steel (equivalent to AISI 1045 / C45)

• Tensile strength (σb): ≥ 610 MPa

• Yield strength (σs): ≥ 450 MPa

• Elongation: ≥ 17%

• Hardness: HB 180–200

Inner Sleeve (Liner):

• Material: High-chromium cast iron (centrifugal cast)

• Annealed hardness: ≤ HRC 40

• Quenched hardness: HRC 60–67