1. Flange rubber gasket is an integrally formed circular member, and its size and deviation meet and conform to the requirements of national standard GB/T9119-2010 and "Dimensional Tolerance of Solid Rubber Products" Molding and Pressing "(GB/T3672-M3).

2. The flange rubber gasket should be free of bubbles and surface defects that affect its performance, and the bonding edge at the mold joint should be kept to a reasonable minimum.

3. The rubber, accelerator, antioxidant, and vulcanizing agent used in the flange rubber gasket should be non-polluting materials, and the sanitary performance of the flange rubber gasket should be improved, and should comply with the "Drinking Water Transmission and Distribution Equipment and Protective Materials Safety Evaluation Standards" (GB/T 17219-1998).

4. The physical properties of the flange rubber sealing gasket should meet the requirements of "Specification for Rubber Seals for Water Supply, Drainage, and Sewage Pipelines Interface Sealing Ring Materials" (GB/T21873)-2008). 100% of the rubber used to make EPDM flange rubber gaskets is pure EPDM rubber, and it is not allowed to use or mix ordinary rubber and recycled rubber.

5. The marking, packaging, transportation and storage of flange rubber gaskets should comply with the general regulations of rubber sealing products, packaging, transportation and storage (GB/T5721-93).