The API 5L specification covers
seamless (SMLS) and welded (ERW, LSAW, SSAW) steel pipes for the transportation of oil and gas. They are classified according to performance grades
(PSL1 and PSL2) and strength grades (X42-X120).
PSL1: Standard grade, suitable for general pipeline, low requirements.
PSL2: With more stringent chemical composition, mechanical properties and quality control requirements, suitable for harsh working conditions, such as high pressure, high corrosion environment.
API 5L seamless pipe is widely used in deep well drilling, submarine pipeline and high pressure transportation because of its no weld, high strength and good pressure resistance.
API 5L seamless steel pipe manufacturing process
API 5L Seamless tubes (SMLS) are manufactured by
hot-rolled, cold-drawn or extruded processes and are free of welds for better bearing capacity and mechanical properties. Typical manufacturing processes are as follows:
1. Preparation of raw materials
Ingot, billet or round steel is used for initial processing.
Steel smelting methods include oxygen converter, electric furnace or open furnace refining process.
The PSL2 grade requires that the Steel must be
Killed Steel and be treated with fine grains.
2. Hot piercing (piercing - hot rolling process)
A perforator (e.g. Mannesmann perforator) is used to make the billet form a hollow tube embryo.
The billet is further expanded and the initial pipe is formed by rolling process.
3. Cold drawing or hot rolling finishing
Cold drawing process (Cold Drawn) : through multiple cold drawing, to obtain high-precision pipe, suitable for small and medium-sized diameter, high-precision requirements of seamless pipe.
Hot Rolled process: improve the forming speed, suitable for large diameter seamless steel pipe.
4. Heat treatment
PSL1: Usually delivered hot rolled or normalized.
PSL2: Normalizing (N), tempering (T), quenching + tempering (Q&T) can be used to improve strength and toughness.
5. Size correction and detection
Perform mechanical property tests, such as tensile strength, yield strength, ductility tests, etc.
Hydrostatic testing, ultrasonic testing, magnetic particle testing to ensure no defects.
API 5L seamless pipe steel grade classification
According to the tensile strength and yield strength, API 5L can be divided into: X42, X46, X52, X56, X60, X65, X70, X80 and other grades.
Delivery status
|
Pipe grade
|
PSL1
|
PSL2
|
|
X42
|
N
|
N、T、Q&T
|
|
X46
|
N
|
N、T、Q&T
|
|
X52
|
N
|
N、T、Q&T
|
|
X56
|
N
|
N、T、Q&T
|
|
X60
|
N
|
N、T、Q&T
|
|
X65
|
N
|
N、T、Q&T
|
|
X70
|
N
|
N、T、Q&T
|
|
X80
|
N
|
Q&T
|
Instructions:
"N" stands for Normalized
"T" stands for Tempered.
"Q&T" stands for Quenched & Tempered
PSL2 grade steel pipe has more stringent chemical composition, tensile properties and impact toughness requirements, suitable for high pressure, deep Wells, acid environment and other special applications.
API 5L seamless tube chemical composition
The chemical composition of API 5L seamless pipe varies depending on the steel grade, and the general control is as follows (unit: %) :
Chemical Composition for PSL 1 pipe with t ≤ 0.984”
|
Steel Grade
|
Mass fraction, % based on heat and product analyses a,g
|
|
C
|
Mn
|
P
|
S
|
V
|
Nb
|
Ti
|
|
max b
|
max b
|
max
|
max
|
max
|
max
|
max
|
|
Seamless Pipe
|
|
A
|
0.22
|
0.9
|
0.3
|
0.3
|
–
|
–
|
–
|
|
B
|
0.28
|
1.2
|
0.3
|
0.3
|
c,d
|
c,d
|
d
|
|
X42
|
0.28
|
1.3
|
0.3
|
0.3
|
d
|
d
|
d
|
|
X46
|
0.28
|
1.4
|
0.3
|
0.3
|
d
|
d
|
d
|
|
X52
|
0.28
|
1.4
|
0.3
|
0.3
|
d
|
d
|
d
|
|
X56
|
0.28
|
1.4
|
0.3
|
0.3
|
d
|
d
|
d
|
|
X60
|
0.28 e
|
1.40 e
|
0.3
|
0.3
|
f
|
f
|
f
|
|
X65
|
0.28 e
|
1.40 e
|
0.3
|
0.3
|
f
|
f
|
f
|
|
X70
|
0.28 e
|
1.40 e
|
0.3
|
0.3
|
f
|
f
|
f
|
|
a. Cu ≤ = 0.50% Ni; ≤ 0.50%; Cr ≤ 0.50%; and Mo ≤ 0.15%,
b. For each reduction of 0.01% below the specified maximum concentration for carbon, an increase of 0.05% above the specified maximum concentration for Mn is permissible, up to a maximum of 1.65% for grades ≥ L245 or B, but ≤ L360 or X52; up to a maximum of 1.75% for grades > L360 or X52, but < L485 or X70; and up to a maximum of 2.00% for grade L485 or X70.,
c. Unless otherwise agreed NB + V ≤ 0.06%,
d. Nb + V + TI ≤ 0.15%,
e. Unless otherwise agreed.,
f. Unless otherwise agreed, NB + V = Ti ≤ 0.15%,
g. No deliberate addition of B is permitted and the residual B ≤ 0.001%
|
Chemical Composition for PSL 2 pipe with t ≤ 0.984”
|
Steel Grade
|
Mass fraction, % based on heat and product analyses
|
Carbon Equiv a
|
|
C
|
Si
|
Mn
|
P
|
S
|
V
|
Nb
|
Ti
|
Other
|
CE IIW
|
CE Pcm
|
|
max b
|
max
|
max b
|
max
|
max
|
max
|
max
|
max
|
max
|
max
|
|
Seamless and Welded Pipe
|
|
BR
|
0.24
|
0.4
|
1.2
|
0.025
|
0.015
|
c
|
c
|
0.04
|
e,l
|
0.43
|
0.25
|
|
X42R
|
0.24
|
0.4
|
1.2
|
0.025
|
0.015
|
0.06
|
0.05
|
0.04
|
e,l
|
0.43
|
0.25
|
|
BN
|
0.24
|
0.4
|
1.2
|
0.025
|
0.015
|
c
|
c
|
0.04
|
e,l
|
0.43
|
0.25
|
|
X42N
|
0.24
|
0.4
|
1.2
|
0.025
|
0.015
|
0.06
|
0.05
|
0.04
|
e,l
|
0.43
|
0.25
|
|
X46N
|
0.24
|
0.4
|
1.4
|
0.025
|
0.015
|
0.07
|
0.05
|
0.04
|
d,e,l
|
0.43
|
0.25
|
|
X52N
|
0.24
|
0.45
|
1.4
|
0.025
|
0.015
|
0.1
|
0.05
|
0.04
|
d,e,l
|
0.43
|
0.25
|
|
X56N
|
0.24
|
0.45
|
1.4
|
0.025
|
0.015
|
0.10f
|
0.05
|
0.04
|
d,e,l
|
0.43
|
0.25
|
|
X60N
|
0.24f
|
0.45f
|
1.40f
|
0.025
|
0.015
|
0.10f
|
0.05f
|
0.04f
|
g,h,l
|
As agreed
|
|
BQ
|
0.18
|
0.45
|
1.4
|
0.025
|
0.015
|
0.05
|
0.05
|
0.04
|
e,l
|
0.43
|
0.25
|
|
X42Q
|
0.18
|
0.45
|
1.4
|
0.025
|
0.015
|
0.05
|
0.05
|
0.04
|
e,l
|
0.43
|
0.25
|
|
X46Q
|
0.18
|
0.45
|
1.4
|
0.025
|
0.015
|
0.05
|
0.05
|
0.04
|
e,l
|
0.43
|
0.25
|
|
X52Q
|
0.18
|
0.45
|
1.5
|
0.025
|
0.015
|
0.05
|
0.05
|
0.04
|
e,l
|
0.43
|
0.25
|
|
X56Q
|
0.18
|
0.45f
|
1.5
|
0.025
|
0.015
|
0.07
|
0.05
|
0.04
|
e,l
|
0.43
|
0.25
|
|
X60Q
|
0.18f
|
0.45f
|
1.70f
|
0.025
|
0.015
|
g
|
g
|
g
|
h,l
|
0.43
|
0.25
|
|
X65Q
|
0.18f
|
0.45f
|
1.70f
|
0.025
|
0.015
|
g
|
g
|
g
|
h,l
|
0.43
|
0.25
|
|
X70Q
|
0.18f
|
0.45f
|
1.80f
|
0.025
|
0.015
|
g
|
g
|
g
|
h,l
|
0.43
|
0.25
|
|
X80Q
|
0.18f
|
0.45f
|
1.90f
|
0.025
|
0.015
|
g
|
g
|
g
|
i,j
|
As agreed
|
|
X90Q
|
0.16f
|
0.45f
|
1.9
|
0.02
|
0.01
|
g
|
g
|
g
|
j,k
|
As agreed
|
|
X100Q
|
0.16f
|
0.45f
|
1.9
|
0.02
|
0.01
|
g
|
g
|
g
|
j,k
|
As agreed
|
|
a. SMLS t>0.787”, CE limits shall be as agreed. The CEIIW limits applied fi C > 0.12% and the CEPcm limits apply if C ≤ 0.12%,
b. For each reduction of 0.01% below the specified maximum for C, an increase of 0.05% above the specified maximum for Mn is permissible, up to a maximum of 1.65% for grades ≥ L245 or B, but ≤ L360 or X52; up to a maximum of 1.75% for grades > L360 or X52, but < L485 or X70; up to a maximum of 2.00% for grades ≥ L485 or X70, but ≤ L555 or X80; and up to a maximum of 2.20% for grades > L555 or X80.,
c. Unless otherwise agreed Nb = V ≤ 0.06%,
d. Nb = V = Ti ≤ 0.15%,
e. Unless otherwise agreed, Cu ≤ 0.50%; Ni ≤ 0.30% Cr ≤ 0.30% and Mo ≤ 0.15%,
f. Unless otherwise agreed,
g. Unless otherwise agreed, Nb + V + Ti ≤ 0.15%,
h. Unless otherwise agreed, Cu ≤ 0.50% Ni ≤ 0.50% Cr ≤ 0.50% and MO ≤ 0.50%,
i. Unless otherwise agreed, Cu ≤ 0.50% Ni ≤ 1.00% Cr ≤ 0.50% and MO ≤ 0.50%,
j. B ≤ 0.004%,
k. Unless otherwise agreed, Cu ≤ 0.50% Ni ≤ 1.00% Cr ≤ 0.55% and MO ≤ 0.80%,
l. For all PSL 2 pipe grades except those grades with footnotes j noted, the following applies. Unless otherwise agreed no intentional addition of B is permitted and residual B ≤ 0.001%.
|
API 5L seamless pipe is the main application
API 5L seamless pipe is widely used in oil, gas, chemical, pipeline transportation and other fields, including:
Oil and gas pipeline
Mainly used in onshore and subsea pipelines, high pressure, high temperature transport of crude oil, refined oil and natural gas.
Oil refining and chemical industry
API 5L PSL2 seamless pipe can be used for high temperature, high pressure, strong corrosion resistance of chemical pipelines.
Deep sea and acidic environment
For Marine pipelines and acid gas fields that require more stringent corrosion resistance and high pressure resistance, X65, X70, X80 grade PSL2 steel pipes are more common.
Structure and support piping
API 5L seamless pipes can also be used as high-strength structural pipes such as bridge structures and support steel frames.
Future development of API 5L seamless pipe
With the development of oil and gas production to deep water, high pressure, high corrosion environment, API 5L seamless pipe will be in the direction of higher strength, more corrosion resistance, and lighter weight development, specific trends include:
Improve the tensile strength: such as X90, X100, X120 grade steel pipe development and application.
Optimize corrosion resistance: Add Mo, Ni, Cr and other alloying elements to improve acid gas resistance.
Intelligent production: The application of AI monitoring, automatic welding and inspection, improve quality control accuracy.
Conclusion
API 5L seamless pipe with high strength, corrosion resistance, excellent mechanical properties for oil and gas transmission, offshore engineering, chemical pipelines and other fields. As the global energy industry continues to evolve, this product will play an even more important role in the future.
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