This Standard specifies the product classification, requirements, test methods, inspection rules, and marking, packing, transportation and storage of the malleable cast iron pipe fittings (hereinafter referred to as "fittings").
This Standard is applicable to the fittings connected on general pipelines with nominal dimension (DN) of 6~150 and for transmission of water, oil, air, coal gas and steam. They are intended for the connection of elements threaded in accordance those specified in with GB/T 7306.1 or GB/T 7306.2.
2 Normative References
The following documents are indispensable for the application of this document. For dated references, only the dated edition applies. For undated references, the latest edition (including all the amendments) of the publication referred to applies.
GB/T 192 "General Purpose Metric Screw Threads-Basic Profile"
GB/T 193 "General Purpose Screw Threads-Diameters and Pitches"
GB/T 196 "General Purpose Screw Threads-Basic Dimensions for Diameter from 1 to 600mm"
GB/T 197 "General Purpose Screw Threads-Tolerances and Fits for Diameter from 1 to 355mm"
GB/T 2828.1 "Sampling procedures for inspection by attributes-Part 1: Sampling Schemes Indexed by Acceptance Quality Limit (AQL) for Lot-by-lot Inspection"
GB/T 2829 "Sampling Procedures and Tables for Periodic Inspection by Attributes (Apply to Inspection of Process Stability)"
GB/T 4956 "Non-magnetic Coatings on Magnetic Substrates-Measurement of Coating Thickness-Magnetic Method"
GB/T 7306.1 "Pipe Threads with 55 Degree Thread Angle Where Pressure-tight Joints Are Made on the Threads--Part 1: Parallel Internal and Taper External Threads" (eqv ISO 7-1: 1994)
GB/T 7306.2 "Pipe Threads with 55 Degree Thread Angle Where Pressure-tight Joints Are Made on the Threads--Part 2: Taper Internal and External Threads" (eqv ISO 7-1:1994)
GB/T 7307 "Pipe Threads Where Pressure-tight Joints Are not Made on the Threads"
GB/T 9440 "Malleable Iron Castings"
GB/T 13825 "Metallic Coatings-Hot Dip Galvanized Coatings on Ferrous Materials-Gravimetric Determination of the Mass Per Unit Area"
3 Terms and Definitions
For the purpose of this standard, the following terms and definitions apply.
3.1
Fitting
Connecting piece, of one or more parts
3.2
Fitting size
Designation of thread size
Size designation of the threads of the threaded outlets that meet the pipe threads given in GB/T 7306.1 or GB/T 7306.2.
Note: The relationship between fitting size (namely the designation of thread size) and nominal dimension (DN) is given in Table 1.
Table 1
Fitting size 1/8 1/4 3/8 1/2 3/4 1 1? 1? 2 2? 3 4 5 6
Nominal dimension DN 6 8 10 15 20 25 32 40 50 65 80 100 125 150
3.3
Reinforcement
Additional material on the outside diameter of an internally threaded fitting in the form of a band or bead (see Figure 1).
