Note: We can also organize production of pipes according to API <<Recommended Practice for
Design, Construction, Operation and Maintenance of Offshore Hydrocardon Pipelines>> and Det
Norske Veritas's <<Rules for Submaring Pipeline Systems>> etc, required by the customers.
MAIN QUALITY INDEX OF STEEL PIPE
Item
Line Pipe
API 5L
GB/T9711.1-1997
O. D. tolerance
of pipe ends
+2.38mm
-0.79mm
+2.38mm
-0.79mm
Tolerance of
wall thickness
D<475.2mm+15.0%t,-12.5%t
D>508mm+19.5%t,-8.0%t
D<475.2mm+15.0%t,-12.5%t
D>508mm+19.5%t,-8.0%t
Straightness
<0.2%L
<0.2%L
Out-of-Roundness
D>508mm±1.0%D
D>508mm±1.0%D
Conditions of
Pipe ends
Bevel angle 30o--35o
Root face 1.59±0.79mm
Square-cut <1.59mm
Bevel angle 30o--35o
Root face 1.59±0.79mm
Square-cut <1.59mm
Tolerance
of weight
Single lengths +10.0%,-3.5%
Carload lots -1.75%
Single lengths +10.0%,-3.5%
Carload lots -1.75%
Non-destructive
inspection
100% X-ray or 100% UT
plus X-ray at both ends
100% X-ray or 100% UT
plus X-ray at both ends
Hydrostatic test
P=2St/D
D<508mm,S=0.85R t0.5
D>508mm,S=0.90R t0.5
P=2St/D
D<508mm,S=0.85R t0.5
D>508mm,S=0.90R t0.5
Remarks
D: Nominal outside diameter, mm T: Nominal wall thickness, mm
S: Fiber stress, MPa L: Length of single pipe, m
P: Hydrostatic test pressure, MPa R t0.5: Yield Strength, MPa
MECHANICAL PROPERTIES AND CHEMICAL ANALYSIS OF STEEL PIPES
Petroleum Pipe