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API 5L Pipes for Pipelines Explained

With this article, you learn about API 5L pipes. The API 5L specification covers seamless and welded pipes to convey oil, gas, water in the natural oil & gas and petrochemical industries. API 5L line pipes are available in multiple carbon steel grades, designated as Grade B, X42, X46, X52, X56, X60, X70, X80 and in PSL1 or PSL2 specification levels. 

API 5L SPECIFICATION

The API 5L specification covers pipes to conveying oil, gas, water in the petroleum, gas and water distribution industries. The API 5L specification latest edition can be read on the API website directly.
API 5L pipe
API 5L Pipes Tenaris

API 5L pipes may be classified according to the following criteria:

The main advantages of API 5L pipe are:

  • Resistance to cracking forces that may propagate in long pipelines
  • Sour service suitability
  • Rather inexpensive and long service life (at least grades B, X42)

Size Range

API 5L pipes are available in dimensions between from 2 to 28″  (seamless execution) and up to 80″ in welded execution (generally, LSAW i.e. longitudinal submerged arc welding).

The API 5L and ASME B36.10 pipe dimensions and weights are, in fact, identical.

API 5L PIPE CHEMICAL AND MECHANICAL PROPERTIES

The yield strength of an API 5L pipe is specified with the number that follows the X in the material grade designation (in kilopounds per square inch – i.e. KSI). So, for instance, an API 5L X52 pipe has a minimum yield strength of 52 KSI.

The table shows the chemical composition of API 5L steel pipes PSL1 and PSL2 from Grade A to Grade X70, as well as their mechanical properties.
Source: API 5L specification

API 5L PIPE PSL1 Chemical and Mechanical Properties

API 5L PIPE PSL1

Chemical Composition

Mechanical Property

C (Max)

Mn (Max)

P (Max)

S (Max)

TENSILE ( Min )

YIELD ( Min )

Psi X 1000

Mpa

Psi X 1000

Mpa

Grade A25

CL I

0.21

0.60

0.030

0.030

45

310

25

172

CL II

0.21

0.60

0.030

0.030

Grade A

0.22

0.90

0.030

0.030

48

331

30

207

Grade B

0.26

1.20

0.030

0.030

60

414

35

241

Grade X42

0.26

1.30

0.030

0.030

60

414

42

290

Grade X46

0.26

1.40

0.030

0.030

63

434

46

317

Grade X52

0.26

1.40

0.030

0.030

66

455

52

359

Grade X56

0.26

1.40

0.030

0.030

71

490

56

386

Grade X60

0.26

1.40

0.030

0.030

75

517

60

414

Grade X65

0.26

1.45

0.030

0.030

77

531

65

448

Grade X70

0.26

1.65

0.030

0.030

82

565

70

483

 

API 5L PIPE PSL2 Chemical and Mechanical Properties

API 5L PIPE
PSL2

Chemical Composition

Mechanical Property

C
(Max)

Mn
(Max)

P
(Max)

S
(Max)

Tensile

Yield

C. E. IMPACT ENERGY

Psi x 1000

Mpa

Psi x 1000

Mpa

PCM

IIW

J

FT/LB

Grade B

0.22

1.20

0.025

0.015

60 – 110

414 – 758

35 – 65

241 – 448

0.25

0.43

T/L 27/41

T/L 20/30

Grade X42

0.22

1.30

0.025

0.015

60 – 110

414 – 758

42 – 72

290 – 496

0.25

0.43

T/L 27/41

T/L 20/30

Grade X46

0.22

1.40

0.025

0.015

63 – 110

434 – 758

46 – 76

317 – 524

0.25

0.43

T/L 27/41

T/L 20/30

Grade X52

0.22

1.40

0.025

0.015

66 – 110

455 – 758

52 – 77

359 – 531

0.25

0.43

T/L 27/41

T/L 20/30

Grade X56

0.22

1.40

0.025

0.015

71 – 110

490 – 758

56 – 79

386 – 544

0.25

0.43

T/L 27/41

T/L 20/30

Grade X60

0.22

1.40

0.025

0.015

75 – 110

517 – 758

60 – 82

414 – 565

0.25

0.43

T/L 27/41

T/L 20/30

Grade X65

0.22

1.45

0.025

0.015

77 – 110

531 – 758

65 – 82

448 – 565

0.25

0.43

T/L 27/41

T/L 20/30

Grade X70

0.22

1.65

0.025

0.015

82 – 110

565 – 758

70 – 82

483 – 565

0.25

0.43

T/L 27/41

T/L 20/30

Grade X80

0.22

1.90

0.025

0.015

90 – 120

621 – 827

80 – 102

552 – 705

0.25

0.43

T/L 27/41

T/L 20/30

API 5L Equivalent Grades (ASTM, EN, DIN)

Material grades A53 Gr. B and A106 Gr. B, and also API 5L Gr. X42, are API 5L Gr. B equivalent. It is actually quite common to find on the market pipes that comply, at the same time, with all these specifications (“quadri-norm” marked pipes). While this is true in terms of chemical and mechanical properties, note that the API 5L specification sets more severe requirements and tests than those set for the two equivalent ASTM specifications.

In terms of comparison with EN pipe standards, API 5L Gr. B equivalents are EN 10216-1 P265GH (seamless) and EN 10217-1 P265 (welded) – whereas EN 10216-2 P265 GH is the EN equivalent grade for ASTM A106 Gr. B pipes.

Line Pipe Materials: Werkstoff vs EN vs API
Werkstoff/DIN EN API
1.0486   StE 285 API 5L Grade X42
1.0562   StE 355 P355N API 5L Grade X52
1.8902   StE 420 P420N API 5L Grade X60
1.8905   StE 460 P460N API 5L Grade X70
High Yield Steel Pipes
1.0457   StE 240.7 L245NB API 5L Grade B
1.0484   StE 290.7 L290NB API 5L Grade X42
1.0582   StE 360.7 L360NB API 5L Grade X52
1.8972   StE 415.7 L415NB API 5L Grade X60
– –

API 5L PSL1 VS. API 5L PSL2

API 5L PSL1 and PSL2 are two specification levels that differ in terms of chemical composition and test requirements. The differences between PSL1 and PSL2 are outlined in the two tables below:

PSL GRADE

C, a

  Mn a

P

 S

 Si

V

Nb

Ti

Other

CEIIW

CEpcm

1

0.24

1.40

0.025

0.015

0.45

0.10

0.05

0.04

b,c

.043

0.025

2

0.28

1.40

0.03

0.03

b

b

b

 

Test Requirement API 5L PSL1 API 5L PSL2
Charpy test None required Required for all grades
Seamless NDT test Only if purchaser specifies SR4 SR4 mandatory
Certification Certificates when specified per SR15 Certificates (SR 15.1) mandatory
Traceability Traceable only until all tests are passed, unless SR15 is specified Traceable after completion of tests (SR 15.2) mandatory
Hydrostatic Test Required Required

API 5L PIPE SCHEDULE CHART

DIMENSIONAL RANGE

NPS
(in)
Outside Diameter
(in)
API 5l Pipe Schedule
SCH 10 SCH 20 SCH 30 SCH STD SCH 40 SCH 60 SCH XS SCH 80 SCH 100 SCH 120 SCH 140 SCH 160 SCH XXS
Wall Thickness (in)
1/8 0.405 0.068 0.068 0.095 0.095
1/4 0.540 0.088 0.088 0.119 0.119
3/8 0.675 0.091 0.091 0.126 0.126
1/2 0.840 0.109 0.109 0.147 0.147 0.187 0.294
3/4 1.050 0.113 0.113 0.154 0.154 0.219 0.308
1 1.315 0.133 0.133 0.179 0.179 0.250 0.358
1 1/4 1.660 0.140 0.140 0.191 0.191 0.250 0.382
1 1/2 1.900 0.145 0.145 0.200 0.200 0.281 0.400
2 2.375 0.154 0.154 0.218 0.218 0.344 0.436
2 1/2 2.875 0.203 0.203 0.276 0.276 0.375 0.552
3 3.500 0.216 0.216 0.300 0.300 0.438 0.600
3 1/2 4.000 0.226 0.226 0.318 0.318
4 4.500 0.237 0.237 0.337 0.337 0.438 0.531 0.674
5 5.563 0.258 0.258 0.375 0.375 0.500 0.625 0.750
6 6.625 0.280 0.280 0.432 0.432 0.562 0.719 0.864
8 8.625 0.250 0.277 0.322 0.322 0.406 0.500 0.500 0.594 0.719 0.812 0.906 0.875
10 10.750 0.250 0.307 0.365 0.365 0.500 0.500 0.594 0.719 0.844 1.000 1.125 1.000
12 12.750 0.250 0.330 0.375 0.406 0.562 0.500 0.688 0.844 1.000 1.125 1.312 1.000
14 14.000 0.250 0.312 0.375 0.375 0.438 0.594 0.500 0.750 0.938 1.094 1.250 1.406
16 16.000 0.250 0.312 0.375 0.375 0.500 0.656 0.500 0.844 1.031 1.219 1.438 1.594
18 18.000 0.250 0.312 0.438 0.375 0.562 0.750 0.500 0.938 1.156 1.375 1.562 1.781
20 20.000 0.250 0.375 0.500 0.375 0.594 0.812 0.500 1.031 1.281 1.500 1.750 1.969
22 22.000 0.250 0.375 0.500 0.375 0.875 0.500 1.125 1.375 1.625 1.875 2.125
24 24.000 0.250 0.375 0.562 0.375 0.688 0.969 0.500 1.219 1.531 1.812 2.062 2.344
30 30.000 0.312 0.500 0.625 0.375 0.500
32 32.000 0.312 0.500 0.625 0.375 0.688
34 34.000 0.312 0.500 0.625 0.375 0.688
36 36.000 0.312 0.500 0.625 0.375 0.750
42 42.000 0.500 0.625 0.375 0.750

API 5L PIPE OUTSIDE DIAMETER TOLERANCE

Specified outside
diameter D mm (in) of API 5L Pipes

API 5L Diameter tolerances mm (in)

API 5L Out-of-roundness tolerances mm (in)

Pipe except at end a

Pipe end a,b,c

Pipe except at end a

Pipe end a,b,c

SMLS pipe

Welded pipe

SMLS pipe

Welded pipe

< 60.3 (2.375)

– 0.8 (0.031 ) to + 0.4 (0.016)

– 0.4 (0.016) to + 1.6 (0.063)

d

≥ 60.3 (2.375)
to
≤ 168.3 (6.625)

± 0.007 5 D

0.020 D

0.015 D

≥ 168.3 (6.625)
to
≤ 610 (24.00)

± 0.007 5 D

± 0.007 5 D

but maximum

of + 3.2 (0.125)

± 0.005 D,

but maximum of ± 1.6 (0.063)

> 610 (24.000)
to
≤ 1 422 (56.00)

± 0.01 D

± 0.005 D,

but maximum

of + 4.0 (0.160)

± 2.0 (0.079)

± 1.6 (0.063)

0.015 D

0.01 D,

but maximum of
15 (0.6),

but maximum of 13 (0.5),

for d / ts ≤ 75

for d / ts ≤ 75

by agreement

by agreement

for d / ts > 75

for d / ts > 75

> 1 422 (56 000)

as agreed

a — Pipe end includes a length of 100 mm (4.0 in) for each side
b — For SMLS pipe, the tolerances apply for 25.0 mm (0.984 in); tolerances for thicker pipes have to be as agreed.
c — For pipe with D219,1 mm (8.625 in) the diameter tolerance and the out-of-roundness tolerance may be determined by using the calculated inside diameter (the specified outside diameter minus two times the specified wall thickness) or measured inside diameter rather than the specified outside diameter
d — Included in the tolerance of the diameter

API 5L PIPE WALL THICKNESS TOLERANCE (WT)

API 5L wall thickness t
mm (in)

API 5L Pipes Tolerances a
mm (in) mm (in)

API 5L SMLS pipe b

≤ 4,0 ( 0.157)

+ 0,6 (0.024)
– 0,5 (0.020)

> 4,0 ( 0.157) to < 25,0 (0.984)

+ 0,150
– 0,125

≥ 25,0 (0.984)

+3,7 (0.146) or + 0,1 t whichever is the greater
– 3,0 (0.120) or – 0,1 t whichever is the greater

API 5L Welded pipe c, d

≤ 5,0 (0.197)

± 0,5 (0.020)

> 5,0 (0.197) to <15,0 (0.591 )

± 0, 1 t

 ≥ 15,0 (0.591)

±1,5 (0.060)

a — if the purchase order specifies a minus tolerance for wall thickness smaller than the applicable value given in this table, the plus tolerance for wall thickness shall be increased by an amount sufficient to maintain the applicable tolerance range.
b — for pipe with D ≥ 355,6 mm (14.000 in) and t ≥ 25,0 mm (0.984 in) the wall thickness tolerance locally may exceed the plus tolerance for wall thickness by an additional 0,05 t, provided that the plus tolerance for mass (see 9.14) is not exceeded.
c — The plus tolerance for wall thickness does not apply to the weld area.
d — See 9.13.2 for additional restrictions.

API 5L MONOGRAM

Manufacturers of steel pipes may request API an audit to assess their capabilities to comply with the API 5L standard.

Pipe mills that pass the API audit successfully are awarded an API monogram.

API lists in a composite index the names of the factories that have passed the audit successfully. The monogram has an expiration date.
The API monogram is therefore similar to franchising scheme, however, API does not have any financial benefit from the certification of pipe mills, nor does it take any liability and the performance of the certified mills and products.

Example of API 5L Monogram

HOW TO ORDER

Parameter API 5L Pipe Ordering Details
Qty Feet or lengths
Size NPS (Outside Diameter) and Schedule Number (Average Wall Thickness)
PSL PSL 1 or PSL 2
Material Grade Grade A, Grade B, X42, X46, X52, X60, X70, X80, etc
Execution Seamless or Welded execution
Surface finish Bare, Black, FBE, etc
Marking requirements If different from the API 5L Specification
Pipe coating or lining requirements To protect the pipe from erosion and corrosion, depending on the fluid to be conveyed
Manufacturer Approved Manufacturer List (AML), or Country of Origin restrictions
Sour service Yes / No

We recommend purchasing the API5L specification from the API store to get a complete understanding of this topic.

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