This standard specifies the dimensions and technical requirements for non-metallic soft gaskets for pressure vessel flanges. This standard is applicable to JB/T 4701-2000 "Type A Flat Welding Flange", JB/T 4702-2000 "Type B Flat Welding Flange" and JB/T 4703-2000 "Long Neck Butt Welding Flange". Metal soft spacer.