1 Scope
This standard specifies the requirements in symbol and code number, dimension and tolerance, material, manufacturing, inspection, test, marking, protection and package of carbon steel, alloy steel and stainless steel butt welding of DN 15 ~ DN 800 (NPS 1/2 ~ NPS 24).
2 Normative Reference
The following documents contain provisions which, through reference in this text, constitute provisions of this code. For dated reference, subsequent amendments (excluding correction) to, or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this standard are encouraged to study whether the latest edition of these documents is applicable. For undated references, the latest edition of the referenced document 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 sheets and wide strips
GB/T 713 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 1047 Pipework components--Definition and selection of DN (nominal size) (ISO 6708: 1995; MOD)
GB 3087 Seamless steel tubes for low and medium pressure boiler
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 plate
GB 3531 Low alloy steel plates for low temperature pressure vessels
GB/T 4237 Hot rolled stainless steel plate
GB/T 4238 Heat-resisting steel sheets and plates
GB 5310 Seamless steel tubes and pipes for high pressure boiler
GB 6479 Seamless steel tubes for high-pressure for chemical fertilizer equipments
GB 6654 Steel plates for pressure vessels
GB/T 8163 Seamless Steel Tubes for Liquid Service (neq ISO 559: 1991)
GB/T 9118.1-2000 Loose hubbed steel pipe flanges with welding neck collar with raised face
GB/T 9118.2-2000 Loose hubbed steel pipe flanges with welding neck collar with ring-joint face
GB/T 9124-2000 Specification for steel pipe flanges
GB/T 9948 Seamless steel tubes for petroleum cracking
GB/T 14976 Stainless Steel Seamless Tubes for Fluid Transport (ASTM A 269: 2000 NEQ)
JB 4730 Nondestructive Testing of Pressure Vessels
ASME B 16.5 Flanges and flanged fittings
ASME B 16.9: 2001 Factory-Made Wrought Buttwelding Fittings
ASME B 36.10M: 1996 Welded and Seamless Wrought Steel Pipe
ASME B 36.19 M: 1985 (R 1994) Stainless steel tubes
3 Symbol and Code Number
3.1 Symbols
DN——Nominal dimension of metric pipe fittings; non-measured value (see GB/T 1047);
NPs——Nominal dimension of British 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;
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 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);
F——Length of lap joint stub end;
G——External diameter of lap joint;
H——Distance from a end face to the other end face of a reducing joint;
K——Distance of from a end face to the top of a 180° elbow;
M——Distance from main body center line to branch pipe end face of tee joint and cross joint;
O——Distance from a end face to the other end face of a 180° elbow;
R——Radius of rounded angle;
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;
T——Thickness of lap joint.
3.2 Code Number
The type and code number of butt welding seamless pipe fittings are detailed in Table 1.
Table 1: type and code number of pipe fittings
Type Model Code number
45°elbow Long radius 45E (L)
90°elbow Long radius 90E (L)
Short radius 90E (S)
Long radius reducing 90E (L) R
180°elbow Long radius 180E (L)
Short radius 180E (S)
Reducing joint
(Smaller end) Concentrical R (C)
Eccentric R (E)
Tee joint Equal-diameter T (S)
Different-diameter (reducing) T (R)
Cross joint Equal-diameter CR (S)
Different-diameter (reducing) CR (R)
Pipe cape C
Lap joint stub end
Long type SE (L)
Short type SE (S)
4 Dimension and Tolerance
4.1 Normal dimension
4.1.1 The dimension of pipe fittings shall meet the requirements of Figure 1 ~Figure 10 and Table 3 ~Table 12; the external diameters of pipe fittings end come with series I and II. Series I referes to international one, and the classification for wall thickness of seamless steel tube connective to Series I pipe fittings are detailed in Appendix B.
4.1.2 For the convenience of for the convenience of international trade, the inch size (dimension)of Series I pipe fittings are detailed in Appendix A.
4.1.3 The user must respectively adopt two unit systems because the metric unit and the British unit has different accuracy. As for the pipe fittings in metric unit system, the nominal dimension hereof is indicated by DN; as for the pipe fittings in British unit system, the nominal dimension hereof is indicated by NPS. The relation of DN and NPS is detailed in Table 2.
Table 2: comparison table for DN and NPS
DN 15 20 25 32 40 50 65 80 90 100
NPS 1/2 3/4 1
2
3
4
Note: where NPS is larger 4, DN is equal to 25 × (NPS).
4.2 Special dimension
4.2.1 In the application of the products involved with fatigue loads, the purchaser shall provide the required minimum size.
4.2.2 The application condition and the connection structure generally determine the length of lap joint stub end, so the purchaser, in order, must specify the long type or the short type lap joint stub end (See Note 2 in Table 10).
4.3 Tolerance
The dimensional tolerance and the form and position tolerance of pipe fittings shall meet the requirements specified in Table 13and Figure 11.
1 Scope
2 Normative Reference
3 Symbol and Code Number
4 Dimension and Tolerance
5 Materials
6 Manufacturing and Heat Treatment
7 Inspection
8 Design Verification Test
9 Product Test
10 Marking
11 Protection and Package
12 Product Quality Certificate
Appendix A (Informative) Inch size of Steel Butt-welding Seamless Pipe Fittings
Appendix B (Informative) Wall Thickness Classification of Seamless Steel Tube Connected With Pipe Fittings
