The selection of steel pipes, fittings, and lining materials should meet the requirements of HG/T4584-2014 specifications. Steel lined PTFE pipes and fittings should adopt a high-pressure forming process that is resistant to negative pressure and full vacuum conditions, with a forming pressure of not less than 30MPa and a holding time of not less than 10min. The formed PTFE seal should be greater than 2.25g/cm3. Mechanical properties of formed steel lined PTFE pipes and fittings ASM1545 acceptance requirements for finished products.