API 5L Line Pipe - Coated Exterior Surface

API 5L Line Pipe

Products details
Tolerance table
Chemical composition

API 5L Line Pipe Standard 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.

In a word, API 5L pipe is the carbon steel pipe applied to the oil and gas transmission system. Meanwhile other fluids like steam, water, slurry also could adopt the API 5L standard for the transmission purposes.

Different Manufacturing Types

API 5L specification covers the manufacturing types in welded and seamless.

Welded Type: ERW, SAW, DSAW, LSAW, SSAW, HSAW Pipe

For API 5L welded pipe common types as Follows:

ERW: Electric Resistance Welded, for pipe diameter normally under 24 inch.

DSAW/SAW: Double Submerged Arc Welding / Submerged Arc Welding, a substitute welding method than ERW for larger diameter pipes.

LSAW: Longitudinal SAW, for diameter up to 48 inch. Also called JCOE manufacturing process.

SSAW/HSAW: Spiral Subemerged Arc Welded / Helical SAW, pipe diameters up to 100 inch.

Seamless Type: Hot Rolled Seamless and Cold Rolled Seamless Pipe

Seamless manufacturing type usually for the small diameters pipe, normally diameter under 24 inch.

(For the pipe diameter is less than 150 mm or 6 inch, the seamless steel pipe is more applied than steel pipe in welded.)

There are also big diameters seamless pipe. By hot rolled manufacturing process we could get seamless pipe diameters at most 20 inch (508 mm). But if you need the seamless pipe more than 20", we can get it through hot expanding processes, maximum diameters to 40 inch 1016 mm.

API 5L Line Pipe 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
PSL2	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

API 5L Line Pipe 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
Welded Pipe
A	0.22	0.9	0.3	0.3	–	–	–
B	0.26	1.2	0.3	0.3	c,d	c,d	d
X42	0.26	1.3	0.3	0.3	d	d	d
X46	0.26	1.4	0.3	0.3	d	d	d
X52	0.26	1.4	0.3	0.3	d	d	d
X56	0.26	1.4	0.3	0.3	d	d	d
X60	0.26 e	1.40 e	0.3	0.3	f	f	f
X65	0.26 e	1.45 e	0.3	0.3	f	f	f
X70	0.26e	1.65 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%

API 5L Line Pipe 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
Welded Pipe
BM		0.22		0.45		1.2		0.025		0.015		0.05		0.05		0.04		e,l	0.43	0.25
X42M		0.22		0.45		1.3		0.025		0.015		0.05		0.05		0.04		e,l	0.43	0.25
X46M		0.22		0.45		1.3		0.025		0.015		0.05		0.05		0.04		e,l	0.43	0.25
X52M		0.22		0.45		1.4		0.025		0.015		d		d		d		e,l	0.43	0.25
X56M		0.22		0.45f		1.4		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	0.43f	0.25

API 5L Line Pipe 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.

API 5L Line Pipe Tolerances: Outside diameter, out of roundness and wall thickness

Specified Outside Diameter D (in)	Diameter Tolerance, inches d				Out-of-Roundness Tolerance in
	Pipe except the end a		Pipe end a,b,c		Pipe except the End a	Pipe End a,b,c
	SMLS Pipe	Welded Pipe	SMLS Pipe	Welded Pipe
< 2.375	-0.031 to + 0.016		-0.031 to + 0.016		0.048	0.036
≥2.375 to 6.625	+/- 0.0075D		-0.016 to + 0.063		0.020D	0.015D
>6.625 to 24.000	+/- 0.0075D	+/- 0.0075D, but max of 0.125	+/- 0.005D, but max of 0.063		0.020D	0.015D
>24 to 56	+/- 0.01D	+/- 0.005D but max of 0.160	+/- 0.079	+/- 0.063	0.015D but max of 0.060	0.01D but max of 0.500
>56	As agreed
a. The pipe end includes a length of 4 in at each of the pipe extremities
b. For SMLS pipe the tolerance apply for t≤0.984in and the tolerances for the thicker pipe shall be as agreed
c. For expanded pipe with D≥8.625in and for non-expanded pipe, the diameter tolerance and the out-of-roundness tolerance may be determined using the calculated inside diameter or measured inside diameter rather than the specified OD.
d. For determining compliance to diameter tolerance, the pipe diameter is defined as the circumference of the pipe in any circumferential plane divide by Pi.

Wall thickness	Tolerances a
t inches	inches
SMLS pipe b
≤ 0.157	-1.2
> 0.157 to < 0.948	+ 0.150t / – 0.125t
≥ 0.984	+ 0.146 or + 0.1t, whichever is the greater
	– 0.120 or – 0.1t, whichever is the greater
Welded pipe c,d
≤ 0.197	+/- 0.020
> 0.197 to < 0.591	+/- 0.1t
≥ 0.591	+/- 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≥ 14.000 in and t≥0.984in, the wall thickness tolerance locally may exceed the plus tolerance for wall thickness by an additional 0.05t provided that the plus tolerance for mass is not exceeded.
c. The plus tolerance for wall thickens does not apply to the weld area
d. See the full API5L spec for full details

Tolerance table

API 5L Steel Pipe Tolerance on Dimensions

Standard	Out Diameter		Wall Thickness
API 5L	Tolerance		Tolerance
	D<60.3	+0.41mm, -0.80mm	+15.0%, -12.5%
	D≥60.3	+0.75%D, -0.75%D	+15.0%, -12.5%

Chemical composition

Chemical Analysis (%) of API 5L Line Pipe

Standard	Class	Grade		Yield strength not less than (MPa)	Tensile strength (MPa)	Elongation(%)	Y.S/T.S
API SPEC 5L ISO 3183	PLS1	L245B	min	245	415	b	-
		L290X42	min	290	415	b	-
		L320X46	min	320	435	b	-
		L360X52	min	360	460	b	-
		L390X56	min	390	490	b	-
		L415X60	min	415	520	b	-
		L450X60	min	450	535	b	-
		L485X70	min	485	570	b	-
	PLS2	L245N BN	min	245	415	b	-
		L245M BM	max	450	760	b	0.93
		L290NX42N	min	290	415	b	-
		L290MX42M	max	495	760	b	0.93
		L320NX46N	min	320	435	b	-
		L320MX46M	max	525	760	b	0.93
		L360NX52N	min	360	460	b	-
		L360MX52M	max	530	760	b	0.93
		L390NX56N	min	390	490	b	-
		L390MX56M	max	545	760	b	0.93
		L415NX60N	min	415	520	b	-
		L415MX60M	max	565	760	b	0.93
		L450MX65M	min	450	535	b	-
		L450MX65M	max	600	760	b	0.93
		L485MX70M	min	485	570	b	-
		L485MX70M	max	635	760	b	0.93
		L555MX80M	min	555	625	b	-
		L555MX80M	max	705	825	b	0.93

Mechanical Properities of API 5L Line Pipe

Standard	Type of pipe	Class	Grade	C	Si	Mn	P	S	V	Nb	Ti
Standard	Type of pipe	Class	Grade	max	max	max	max	max	max	max	max
API SPEC 5L	SMLS	PLS1	L245 B L290 X42 L320 X46 L360 X52 L390 X56 L415 X60 L450 X65 L485 X70 L245N BN	0.28 0.28 0.28 0.28 0.28 0.28 0.28 0.28 0.24	0.4	1.20 1.30 1.40 1.40 1.40 1.40 1.40 1.40 1.20	0.030 0.030 0.030 0.030 0.030 0.030 0.030 0.030 0.025	0.030 0.030 0.030 0.030 0.030 0.030 0.030 0.030 0.015	———	———	0.04
		PLS2	L290N X42N	0.24	0.4	1.2	0.025	0.015	0.06	0.05	0.04
			L320N X46N	0.24	0.4	1.4	0.025	0.015	0.07	0.05	0.04
			L360N X52N	0.24	0.45	1.4	0.025	0.015	0.1	0.05	0.04
			L390N X56N	0.24	0.45	1.4	0.025	0.015	0.1	0.05	0.04
			L415N X60N	0.24	0.45	1.4	0.025	0.015	0.1	0.05	0.04
	WELD	PLS1	L245 B	0.26	-	1.2	-	0.03	0.03	-	-
			L290 X42	0.26	-	1.3	-	0.03	0.03	-	-
			L320 X46	0.26	-	1.4	-	0.03	0.03	-	-
			L360 X52	0.26	-	1.4	-	0.03	0.03	-	-
			L390 X56	0.26	-	1.4	-	0.03	0.03	-	-
			L415 X60	0.26	-	1.4	-	0.03	0.03	-	-
			L450 X65	0.26	-	1.45	-	0.03	0.03	-	-
			L485 X70	0.26	-	1.65	-	0.03	0.03	-	-
		PLS2	L245M BM	0.22	0.45	1.2	0.025	0.015	0.05	0.05	0.04
			L290M X42M	0.22	0.45	1.3	0.025	0.015	0.05	0.05	0.04
			L320M X46M	0.22	0.45	1.3	0.025	0.015	0.05	0.05	0.04
			L360M X52M	0.22	0.45	1.4	0.025	0.015	-	-	-
			L390M X56M	0.22	0.45	1.4	0.025	0.015	-	-	-
			L415M X60M	0.12	0.45	1.6	0.025	0.015	-	-	-
			L450M X65M	0.12	0.45	1.6	0.025	0.015	-	-	-
			L485M X70M	0.12	0.45	1.7	0.025	0.015	-	-	-
			L555M X80M	0.12	0.45	1.85	0.025	0.015	-	-	-

Frequently Asked Questions

1. What does PSL2 give me that PSL1 doesn't?

PSL2 is PSL1 + stricter requirements per API 5L 46th Edition Table 8:

Chemical:

(1) Carbon equivalent CE(IIW) ≤ 0.43% — PSL1 allows up to 0.50%

(2) Carbon ≤ 0.24% — restricts weld cracks

Mechanical:

(3) Yield strength upper limit — prevents over-strength issues

(4) CVN impact mandatory at all thicknesses — PSL1 optional > 10mm

(5) DWTT (Drop Weight Tear Test) for PSL2 — critical for brittle fracture per API 5L Annex A

Testing:

(6) 100% UT of weld seam — PSL1 allows spot testing

(7) Dimensional tolerances tighter

PSL2 required for: gas transmission, offshore, sour service, cold climate per API 5L Section 8.1.

2. What hardness limit applies in sour (H₂S) environments?

The 22 HRC rule per NACE MR0175/ISO 15156-2 Section 7.3.4:

Why hardness? H₂S dissociates at the steel surface → H atoms diffuse in → high hardness = high stress = SSC cracking.

The limit: 22 HRC (or 250 HV10) per ISO 6507-1 = ~280 MPa yield strength threshold per ISO 15156-2 Table A.1.

How to achieve:

(1) Normalize — reduces hardness to ~180 HB per API 5L Section 8.6

(2) Quench + Temper — control hardness distribution within ±3 HRC across wall

(3) TMCP — thermo-mechanical controlled processing per ISO 3183 Annex C

Verification: through-thickness hardness survey per ISO 6507-1: minimum 3 indentations across weld, HAZ, and base metal per API 5L Section 10.2.2.6.

3. When should I choose seamless over welded for line pipe?

Seamless preferred per API 5L Section 8.2 when:

(1) OD ≤ 20" (500mm) — above this, welded more economical

(2) Weld factor E = 1.0 per ASME B31.3 Table A-1B (no joint factor discount)

(3) Threaded ends required — welded threads can crack under makeup torque

(4) Low-temperature service below -20°C — no weld = no stress riser per ISO 3183 Table 9

(5) Sour service per NACE MR0175 — weld HAZ susceptible to SSC

Welded is acceptable when: gas pipeline with 100% UT per API 5L Section 10.2.5 and proper weld factor (E=0.95 for LSAW, E=1.0 if 100% NDE per ASME B31.3).

Cost comparison: seamless ~15-20% premium over LSAW at equivalent OD/WT per EN 1993-1-1 Section 6.

4. What is the Charpy impact requirement for cold climates?

The CVN test for brittle fracture prevention per API 5L Section 9.8:

API 5L baseline: PSL2 requires min 20J average at 0°C for sour service per Table 11.

For cold climates per CSA Z245.1 Section 7.6:

Grade B at -20°C: min 20J (single test ≥ 15J) per API 5L Table 11

X52+ at -30°C: per project specification — typically 27J average, 20J single per DNV-OS-F101 Table 5-2

Why CVN matters: brittle fracture propagates at near-sonic velocity (2100 m/s in steel). Fracture-arrest design per API 5L Annex A uses CVN data for DWTT shear area ≥ 85% for X65+.

Temperature adjustment per ASTM E23 Section 7.5: ±5°C per 2J for sub-size specimens. Full-size (10×10mm) required for qualification per API 5L Section 9.8.2.

5. What is the pig ID clearance for line pipe?

Pipeline pigging clearance per API 5L Section 9.4 and ASME B31.8 Section 845:

Rule of thumb: ID clearance = 2.5% to 5% of pipe ID for cleaning and inspection pigs per API 5L Table 9.

Example: 20" (508mm) × 10mm WT → ID = 488mm → clearance = 12.2-24.4mm

Why clearance:

(1) Wax and paraffin buildup — typical deposition rate 0.5-3mm/year per API 5L Section 8.4.2

(2) Mechanical damage tolerance — dents > 2% OD require repair per ASME B31.8 Section 851.2

(3) Thermal expansion margin — 0.011mm/m per °C for carbon steel

Calculation per ISO 13623: ID = OD - 2 × WT, minimum ID must satisfy: pig OD / 0.95 ≤ ID.

For batch transportation (multi-product pipelines), tighter clearances down to 1.5% possible with intelligent pigs per API 5L Appendix K.

6. What happens when you weld X70 pipe in the field?

Field welding X70 line pipe per API 1104 Section 5 and AWS D1.1 Section 4:

Weld metal matching per API 5L Section 8.4:

(1) Match or slightly overmatch (≤70MPa over) base metal yield per API 1104 Table 3

(2) Weld wire must be ≥ X70 strength — typically ER80S-Ni1 or ER90S-G per AWS A5.28

Pre-heat requirements per API 1104 Section 7.2:

(3) X70 requires 100-150°C preheat for HAZ cracking prevention (carbon equivalent CE ≤ 0.43%, min preheat 100°C per Table 5)

Post-weld treatment:

(4) PWHT at 580-620°C for sour service per NACE MR0175 Section 7.3.4; not mandatory for non-sour per API 1104 Section 12

Common issues per API 5L Section 10.2.3:

(5) Lack of fusion at root — 100% radiographic or UT inspection per ASME Section V required

(6) Hydrogen cracking — electrode moisture ≤ 0.2% per AWS D1.1 Section 5.3; maintain low-hydrogen practice (SMAW with E7018-G, ≤ 4ml/100g diffusible H₂ per ISO 3690)

Procedure qualification: API 1104 Section 4 + AWS D1.1 Section 4.1 required for all grades ≥ X65.

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