Bolted flange joints have always been an important content in the application and maintenance of pressure vessels and piping.However,the installation quality of bolt flange joints has not been effectively guaranteed,resulting in a series of leakage accidents during the actual production process.Therefore,as early as 2000,ASME issued the first ASME PCC-1“Guidelines for Pressure Boundary Bolted Flange Joint Assembly”,which was revised in 2010 and 2013,and the latest ASME PCC-1—2019 was issued in 2019.ASME PCC -1—2019 revised the problems existing in the 2013 version of the guide,and added,deleted and updated the guide in many aspects based on the summary of engineering practice experience.For example,the content of Appendix G “Use of Contractors in Bolting Services” was deleted and an updated Appendix Q “Considerations for the Use of Powered Equipment” was added,and new reference torque tables were introduced in Appendix O.According to the revised content of the new guidelines,ASME PCC -1—2019 was analyzed and explained,which provides reference for the engineering installation of bolted flange connection in China.