API 5L seamless & welded pipe

API 5L is a standard published by the American Petroleum Institute (API) that covers seamless and welded steel line pipe. It is one of the most widely used pipe specifications in the world, specifically designed for the transportation of oil, gas, and water in the pipeline and energy industries. APP stocks API 5L pipe in grades B, X42, X52, X60, X65 & X70.

Manufacturing Types

  • SMLS — Seamless; used where higher integrity and uniformity are required
  • ERW — Electric Resistance Welded; cost-effective, widely used for distribution and gathering lines
  • SAW — Submerged Arc Welded (LSAW or DSAW); used for large diameter transmission pipe

Sizes

  • Seamless from 1/2″ NPS to 36″ OD
  • ERW from 2″ NPS to 26″ OD
  • SAW from 20″ to 60″ OD

Scope

ANSI / API 5L specifies the manufacture of two product levels (PSL1 and PSL2) of seamless and welded steel pipe for the use of a pipeline in the transportation of petroleum and natural gas. For material use in a sour service application, refer to Annex H; for offshore service application, refer to Annex J of API 5L 45th Edition.

Primary Applications & Uses

  • Oil & Gas Transmission (Mainline Pipelines) The core application. Long-distance, high-pressure trunk lines carrying crude oil or natural gas across hundreds or thousands of miles. X65, X70, and X80 grades are typical here, offering the strength needed to handle high operating pressures efficiently.
  • Gas Distribution Networks Lower-pressure networks delivering natural gas to cities, towns, and industrial users. Grades like X42 and X52 are common in this service.
  • Gathering Lines Pipelines that collect oil or gas from wellheads and transport it to processing facilities or trunk lines. Often in challenging environments — sour gas, wet gas, or multiphase flow — where PSL 2 with sour service ratings (HIC/SSC resistance) may be required.
  • Water Injection & Disposal Lines Used in oilfield water handling — injecting water into reservoirs for enhanced oil recovery or disposing of produced water.
  • Offshore Pipeline Systems Subsea flowlines and risers connecting offshore platforms and wells. Requires PSL 2 with stringent toughness and weld quality requirements due to the difficulty of repair and the harsh environment.
  • Slurry & Mineral Transport Mining operations use API 5L pipe to transport slurries — mixtures of water and crushed ore — over long distances from mine sites to processing plants.
  • CO₂ Transport (Carbon Capture) Emerging application in carbon capture and sequestration (CCS) projects, where CO₂ is transported under high pressure via pipeline for underground storage.

Delivery condition

PSL Delivery Condition Pipe grade
PSL1 As-rolled, normalized, normalizing formed A
As-rolled, normalizing rolled, thermomechanical rolled, thermo-mechanical formed, normalizing formed, normalized, normalized and tempered or if agreed Q&T SMLS only B
As-rolled, normalizing rolled, thermomechanical rolled, thermo-mechanical formed, normalizing formed, normalized, normalized and tempered X42, X46, X52, X56, X60, X65, X70
PSL 2 As-rolled BR, X42R
Normalizing rolled, normalizing formed, normalized or normalized and tempered BN, X42N, X46N, X52N, X56N, X60N
Quenched and tempered BQ, X42Q, X46Q, X56Q, X60Q, X65Q, X70Q, X80Q, X90Q, X100Q
Thermomechanical rolled or thermomechanical formed BM, X42M, X46M, X56M, X60M, X65M, X70M, X80M
Thermomechanical rolled X90M, X100M, X120M
The suffice (R, N, Q or M) for PSL2 grades, belongs to the steel grade

Chemical requirements

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 0.90 0.03 0.03 – – –
B 0.28 1.20 0.03 0.03 c,d c,d d
X42 0.28 1.30 0.03 0.03 d d d
X46 0.28 1.40 0.03 0.03 d d d
X52 0.28 1.40 0.03 0.03 d d d
X56 0.28 1.40 0.03 0.03 d d d
X60 0.28 e 1.40 e 0.03 0.03 f f f
X65 0.28 e 1.40 e 0.03 0.03 f f f
X70 0.28 e 1.40 e 0.03 0.03 f f f
Welded Pipe
A 0.22 0.90 0.03 0.03 – – –
B 0.26 1.20 0.03 0.03 c,d c,d d
X42 0.26 1.30 0.03 0.03 d d d
X46 0.26 1.40 0.03 0.03 d d d
X52 0.26 1.40 0.03 0.03 d d d
X56 0.26 1.40 0.03 0.03 d d d
X60 0.26 e 1.40 e 0.03 0.03 f f f
X65 0.26 e 1.45 e 0.03 0.03 f f f
X70 0.26e 1.65 e 0.03 0.03 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 0.40 1.20 0.025 0.015 c c 0.04 e,l 0.43 0.25
X42R 0.24 0.40 1.20 0.025 0.015 0.06 0.05 0.04 e,l 0.43 0.25
BN 0.24 0.40 1.20 0.025 0.015 c c 0.04 e,l 0.43 0.25
X42N 0.24 0.40 1.20 0.025 0.015 0.06 0.05 0.04 e,l 0.43 0.25
X46N 0.24 0.40 1.40 0.025 0.015 0.07 0.05 0.04 d,e,l 0.43 0.25
X52N 0.24 0.45 1.40 0.025 0.015 0.10 0.05 0.04 d,e,l 0.43 0.25
X56N 0.24 0.45 1.40 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 1.40 0.025 0.015 0.05 0.05 0.04 e,l 0.43 0.25
X42Q 0.18 0.45 1.40 0.025 0.015 0.05 0.05 0.04 e,l 0.43 0.25
X46Q 0.18 0.45 1.40 0.025 0.015 0.05 0.05 0.04 e,l 0.43 0.25
X52Q 0.18 0.45 1.50 0.025 0.015 0.05 0.05 0.04 e,l 0.43 0.25
X56Q 0.18 0.45f 1.50 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 1.90 0.020 0.010 g g g j,k As agreed
X100Q 0.16f 0.45f 1.90 0.020 0.010 g g g j,k As agreed
Welded Pipe
BM 0.22 0.45 1.20 0.025 0.015 0.05 0.05 0.04 e,l 0.43 0.25
X42M 0.22 0.45 1.30 0.025 0.015 0.05 0.05 0.04 e,l 0.43 0.25
X46M 0.22 0.45 1.30 0.025 0.015 0.05 0.05 0.04 e,l 0.43 0.25
X52M 0.22 0.45 1.40 0.025 0.015 d d d e,l 0.43 0.25
X56M 0.22 0.45f 1.40 0.025 0.015 d d d e,l 0.43 0.25
X60M 0.12f 0.45f 1.60f 0.025 0.015 g g g h,l 0.43 0.25
X65M 0.12f 0.45f 1.60f 0.025 0.015 g g g h,l 0.43 0.25
X70M 0.12f 0.45f 1.70f 0.025 0.015 g g g h,l 0.43 0.25
X80M 0.12f 0.45f 1.85f 0.025 0.015 g g g i,j .043f 0.25
X90M 0.1 0.55f 2.10f 0.02 0.01 g g g i,j – 0.25
X100M 0.1 0.55f 2.10f 0.02 0.01 g g g i,j – 0.25
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%.

Mechanical properties

Pipe Grade Tensile Properties – Pipe Body of SMLS and Welded Pipes PSL 1 Seam of Welded Pipe
Yield Strength a Tensile Strength a Elongation Tensile Strength b
Rt0,5 PSI Min Rm PSI Min (in 2in Af % min) Rm PSI Min
A 30,500 48,600 c 48,600
B 35,500 60,200 c 60,200
X42 42,100 60,200 c 60,200
X46 46,400 63,100 c 63,100
X52 52,200 66,700 c 66,700
X56 56,600 71,100 c 71,100
X60 60,200 75,400 c 75,400
X65 65,300 77,500 c 77,500
X70 70,300 82,700 c 82,700
a. For intermediate grade, the difference between the specified minimum tensile strength and the specified minimum yield for the pipe body shall be as given for the next higher grade.
b. For the intermediate grades, the specified minimum tensile strength for the weld seam shall be the same as determined for the body using foot note a.
c. The specified minimum elongation, Af, expressed in percent and rounded to the nearest percent, shall be determined using the following equation:
Where C is 1 940 for calculation using Si units and 625 000 for calculation using USC units
Axc   is the applicable tensile test piece cross-sectional area, expressed in square millimeters (square inches) , as follows
– For circular cross-section test pieces, 130mm2 (0.20 in2) for 12.7 mm (0.500 in) and 8.9 mm (.350 in) diameter test pieces; and 65 mm2 (0.10 in2) for 6.4 mm (0.250in) diameter test pieces.
– For full-section test pieces, the lesser of a) 485 mm2 (0.75 in2) and b) the cross-sectional area of the test piece, derived using the specified outside diameter and the specified wall thickness of the pipe, rounded to the nearest 10 mm2 (0.10in2)
– For strip test pieces, the lesser of a) 485 mm2 (0.75 in2) and b) the cross-sectional area of the test piece, derived using the specified width of the test piece and the specified wall thickness of the pipe, rounded to the nearest 10 mm2 (0.10in2)
U is the specified minimum tensile strength, expressed in megapascals (pounds per square inch)
Pipe Grade Tensile Properties – Pipe Body of SMLS and Welded Pipes PSL 2 Seam of Welded Pipe
Yield Strength a Tensile Strength a Ratio a,c Elongation Tensile Strength d
Rt0,5  PSI Min Rm  PSI Min R10,5IRm (in 2in) Rm (psi)
Af %
Minimum Maximum Minimum Maximum Maximum Minimum Minimum
BR, BN,BQ,BM 35,500 65,300 60,200 95,000 0.93 f 60,200
X42,X42R,X2Q,X42M 42,100 71,800 60,200 95,000 0.93 f 60,200
X46N,X46Q,X46M 46,400 76,100 63,100 95,000 0.93 f 63,100
X52N,X52Q,X52M 52,200 76,900 66,700 110,200 0.93 f 66,700
X56N,X56Q,X56M 56,600 79,000 71,100 110,200 0.93 f 71,100
X60N,X60Q,S60M 60,200 81,900 75,400 110,200 0.93 f 75,400
X65Q,X65M 65,300 87,000 77,600 110,200 0.93 f 76,600
X70Q,X65M 70,300 92,100 82,700 110,200 0.93 f 82,700
X80Q,X80M 80,.500 102,300 90,600 119,700 0.93 f 90,600
a. For intermediate grade, refer to the full API5L specification.
b. for grades > X90 refer to the full API5L specification.
c. This limit applies for pies with D> 12.750 in
d. For intermediate grades, the specified minimum tensile strength for the weld seam shall be the same value as was determined for the pipe body using foot a.
e. for pipe requiring longitudinal testing, the maximum yield strength shall be ≤ 71,800 psi
f. The specified minimum elongation, Af, expressed in percent and rounded to the nearest percent, shall be determined using the following equation:
Where C is 1 940 for calculation using Si units and 625 000 for calculation using USC units
Axc   is the applicable tensile test piece cross-sectional area, expressed in square millimeters (square inches) , as follows
– For circular cross-section test pieces, 130mm2 (0.20 in2) for 12.7 mm (0.500 in) and 8.9 mm (.350 in) diameter test pieces; and 65 mm2 (0.10 in2) for 6.4 mm (0.250in) diameter test pieces.
–  For full-section test pieces, the lesser of a) 485 mm2 (0.75 in2) and b) the cross-sectional area of the test piece, derived using the specified outside diameter and the specified wall thickness of the pipe, rounded to the nearest 10 mm2 (0.10in2)
–  For strip test pieces, the lesser of a) 485 mm2 (0.75 in2) and b) the cross-sectional area of the test piece, derived using the specified width of the test piece and the specified wall thickness of the pipe, rounded to the nearest 10 mm2 (0.10in2)
   U is the specified minimum tensile strength, expressed in megapascals (pounds per square inch
g. Lower values fo R10,5IRm may be specified by agreement
h. for grades > x90 refer to the full API5L specification.

 

CVN impact test for PSL2

Many PSL2 pipe sizes and grades require CVN. Seamless pipe is to be tested in the body. Welded pipe is to be tested in the body, pipe weld and heat-affected zone. Refer to the full API 5L specification for the chart of sizes and grades and required absorbed energy values.

 

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* This information is provided for quick references. Always consult applicable ASME, ASTM and Manufacture’s standards.