USP a21
Green Tea
ASTM A21-94(1999)
Standard Specification for Carbon Steel Axles, Non-Heat-Treated and Heat-Treated, for Railway Use (Withdrawn 2003)
UNE-EN 60061-1/A21:1999
LAMP CAPS AND HOLDERS TOGETHER WITH GAUGES FOR THE CONTROL OF INTERCHANGEABILITY AND SAFETY. PART 1: LAMP CAPS
AS A21-1964
Specification for burnt clay and shale building bricks
AS A21-1934
Specification for building bricks
AWWA C110/A21.10-21
Ductile-Iron and Gray-Iron Fittings
AWWA C150/A21.50-21
Thickness Design of Ductile-Iron Pipe
GB/T 35157-2017(\u82f1\u6587\u7248)
树脂型合成石板材
AWWA C153/A21.53-19
Ductile-Iron Compact Fittings
AWWA C151/A21.51-17
Ductile-Iron Pipe, Centrifugally Cast, for Water, Includes Errata 1 (2018)
AWWA C105/A21.5-18
Polyethylene Encasement for Ductile-Iron Pipe Systems
AWWA C116/A21.16-15
Protective Fusion-Bonded Coatings for the Interior and Exterior Surfaces of Ductile-Iron and Gray-Iron Fittings for Water Supply Service
AWWA C150/A21.50-14
Thickness Design of Ductile-Iron Pipe
AWWA C111/A21.11-12
Rubber-Gasket Joints for Ductile-Iron Pressure Pipe and Fittings
AWWA C110/A21.10-12
Ductile-Iron and Gray-Iron Fittings
AWWA C153/A21.53-11
Ductile-Iron Compact Fittings
AWWA C150/A21.50-08
Thickness Design of Ductile-Iron Pipe
AWWA C110/A21.10-08
Ductile-Iron and Gray-Iron Fittings
AWWA C153/A21.53-06
Ductile-Iron Compact Fittings for Water Service
AWWA C115/A21.15-05
Standard for Flanged Ductile-Iron Pipe With Threaded Flanges