Probing into deviation of dimension limit of bend used in Shanjing gas pipeline

The mechanical property and bend's dimension limit deviation used in Shanjing gas pipeline are the two major aspects representing 90's international advanced level of the pipeline. By analyzing domestic present situation on bend standards, making reference to domestic relative standards and applicable US fitting standards internationally as well as combining with the experience in making bend with DN 650 X60 longitudinally-welded pipe, we work out our specification for bend applicable for Shanjing gas pipeline project. The dimension limit deviation value of the bend reaches or exceeds US fitting standard MSS SP75-1993 and ASME/ANSI B 16.9-1993 generally. The dimension limit deviation of bend product reaches the requirement of specification basically, which satisfies the requirements of matching fitting, non cutting, non roundness checking and non forced assembling. It is recommended to revise the present bend standard and work out advanced bend and fitting specifications suitable for our country's present situation.