Double metal cylinder is currently the most widely used, one of the largest amount of mud pump fluid end accessories. I produced the double metal cylinder, forging combines high wear jackets and high wear resistance of the advantages of internal corrosion chrome sleeve, jacket made of high quality carbon steel hot forming, inner sleeve made of high chromium cast iron centrifugal casting made. 900000psi coat which has a higher tensile strength, heat-treated after the inner sleeve over HRC60 hardness, liner can withstand the pressure of 7000psi mud, and its inner surface is smooth as a mirror, the hole tight dimensional tolerances, the normal life of up to 800 hours the above. Our products have been certified by the American Petroleum Institute API7K, and in December 2014 by the German Rhine third party entity's certification, product quality have reached the international and domestic leading level, won praise at home and abroad.