1 Scope
This standard specifies the requirements for symbols and code numbers, dimension and tolerance, materials, manufacture, inspection, test, mark, protection and package of DN 150 ~ DN 1200 (NPS 6 ~ NPS 48) carbon steel, alloy steel and stainless steel plate butt-welding pipe fittings.
2 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. For dated reference, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, the parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards. For undated references, the latest edition of the normative document referred to applies.
GB 150 Steel pressure vessels
GB/T 710 Hot-rolled quality carbon structural steel sheets and strips
GB/T 711 Hot-rolled quality carbon structural steel plates and wide strips
GB 713 Carbon and low alloy steel plates for boilers
GB/T 912 Hot-rolled sheets and strips of carbon structural steels and high strength low alloy structural steels
GB/T 985 Basic forms and sizes of weld grooves for gas welding manual arc welding and gas-shielded arc welding
GB/T 986 Basic forms and sizes of weld grooves
GB/T 1047 Pipework components - Definition and selection of DN (nominal size) (ISO 6708:1995, MOD)
GB/T 3274 Hot-rolled plates and strips of carbon structural steels and high strength low alloy structural steels
GB/T 3280 Cold rolled stainless steel sheets and plates
GB 3531 Low alloy steel plates for low temperature pressure vessels
GB/T 4237 Hot rolled stainless steel sheets and plates
GB/T 4238 Heat-resisting steel sheets and plates
GB 6654 Steel plates for pressure vessels
JB 4708 Welding procedure qualification for steel pressure vessels
JB/T 4709 Welding specification for steel pressure vessels
JB/T 4730.1~4730.6-2005 Nondestructive testing of pressure equipments
3 Symbols and Code Numbers
3.1 Symbols
DN——Nominal dimension of metric unit pipe fittings; non-measured value (see GB/T 1047);
NPS——Nominal dimension of imperial unit pipe fittings, non-measured value;
A——Distance of a end face center to the other end face of 90° elbow; distance of 180° elbow center to end face center;
B——Distance from 45° elbow center to end face;
b——Opposite side misalignment of welded joints;
C——Distance from branch outlet axial line of tee joint and cross joint to central body end face;
D——Groove external diameter of elbow, straight tee joint and cross joint, and pipe cap; groove external diameter of reducing fittings large end;
D1——Groove external diameter of reducing fittings smaller end;
E——Total height of pipe cap (pipe seal head);
G——External diameter of lap joint;
H——Distance from a end face to the other end face of a reducing joint;
M——Distance from main body center line to branch pipe end face of tee joint and cross joint;
s——Wall thickness of steel pipe;
t——Required wall thickness of large end welding end of same-diameter or reducing fittings;
t1——Required wall thickness of smaller end welding end of reducing fittings.
3.2 Code numbers
Type and code number of steel plate butt-welding pipe fittings are detailed in Table 1.
GB/T 13401-2005 The following standards are cited：
