I. The Use and Structure of JB593-64 Mirror Flat Welding Mirror and Neck Mirror
　　Visual mirrors are suitable for peeping devices of petroleum, chemical and other industrial equipment to observe the operation of materials inside the equipment. The materials are stainless steel, carbon steel, lining, etc. The maximum operating pressure is 25 kgf/cm2, and the allowable medium temperature is 0-200 C. The material of the mirror glass is tempered borosilicate glass, and the chromaticity temperature difference of the tempered borosilicate glass is 180 C.