GB/T 12721-2007

GB/T 2556-1981 Pipe flanges for ordinary use--Sealing surfaces--Forms and dimensions GB/T 2555-1981 Pipe flange connectors for ordinary use--Mounting dimensions GB/T 4621-1984 Spiral wound gaskets test method of steam sealing characteristics GB/T 3452.3-1988 Fluid power systems--O-ring--Design criteria for O-ring housing--Basic calculation GB/T 9642-1988 Polyethylene (PE) pipes and fittings--Designation of polyethylene based on nominal density and melt flow rate GB/T 13020-1991 Unplasticized polyvinyl chloride (PVC-U) pipes--Tolerances on outside diameters and wall thicknesses GB/T 13019-1991 Polypropylene (PP) pipes--Tolerances on outside diameters and wall thicknesses GB/T 13018-1991 Polyethylene (PE) pipes--Toleranceson outside diameters and wall thicknesses