API 5L Pipes for Pipelines Explained

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 pipes may be classified according to the following criteria:

execution: seamless or welded (seamless pipes may be used up to 24 inches, LSAW above 24 inches, ERW up to 20 inches)
specification level (API PSL1, PSL2): PSL1 is a standard quality used for pipelines, whereas PSL2 sets more stringent chemical, mechanical properties, and testing requirements
surface finish: black, varnish painted, anti-rust oil, galvanized, coated externally (3PL) and/or lined internally
ends types: plain, beveled, threaded ends

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

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
4	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 Dbut maximumof + 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 maximumof + 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.