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:
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
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.

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

The 22 HRC rule per NACE MR0175/ISO 15156:
Why hardness?
H₂S dissociates at the steel surface → H atoms diffuse in →
High hardness = high strength = high stress = cracking
The limit:
22 HRC (or 250 HV10) = ~280 MPa yield strength
How to achieve:
(1) Normalize — reduces hardness to ~180 HB
(2) Quench + Temper — control hardness distribution
(3) TMCP — thermo-mechanical controlled processing
Check: through-thickness hardness survey required.

3. When should I choose seamless over welded?

Seamless preferred when:
(1) OD ≤ 20" (500mm) — above this, welded more economical
(2) Weld factor E = 1.0 (no discount vs seamless)
(3) Threaded ends required — welded threads can crack
(4) Low-temperature service — no weld = no stress riser
(5) Sour service — weld HAZ cracks in sour service
Welded is OK when:
Gas pipeline with 100% UT and proper weld factor (E=0.95 or 1.0)
Cost comparison: Seamless ~15-20% premium over LSAW

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

The CVN test for brittle fracture prevention:
API 5L requirement:
PSL2: min 20J avg at 0°C for sour service
For cold climates, additional requirements:
Grade B at -20°C: min 20J (single test >= 15J)
X52+ at -30°C: per project specification
Why CVN matters:
Brittle fracture propagates at near-sonic velocity.
Fracture-arrest design uses CVN data.
Temperature adjustment:
+/-5°C per 2J (for samples less than full thickness).

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

Pipeline Internal Gas Compressor (Pig) clearance design:
Rule of thumb: ID clearance = 2.5% to 5% of pipe ID
Example: 20" (508mm) → 12.7-25.4mm clearance
Why clearance:
(1) Wax and paraffin buildup
(2) Mechanical damage tolerance
(3) Thermal expansion margin
Calculation: ID = OD - 2 × WT
ID must be: pig OD / 0.95 minimum
For batch transportation, tighter clearances possible.

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

Field welding high-strength line pipe requires:
Weld metal matching:
(1) Match or slightly overmatch base metal yield
(2) Weld wire must be ≥ X70 strength
Pre-heat requirements:
(3) X70+ requires 100-150°C preheat for HAZ cracking
Post-weld treatment:
(4) May require stress relief for sour service
Common issues:
(5) Lack of fusion at root — inspection critical
(6) Hydrogen cracking — keep electrodes dry
Procedure: AWS D1.1 + API 1104 required for qualification.

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