Chemical Requirement for API 5L X65 Sour Service Pipe

May 06, 2025

Chemical Requirement for API 5L X65 Pipe

X65 steel pipe is usually designed to cope with extreme pressure and harsh environment, which is very suitable for oil and gas pipelines that require high durability and reliability. In addition, its excellent mechanical properties and corrosion resistance make it an ideal choice for subsea pipelines and highly corrosive industrial environments.

API 5L X65 specification pipe is also called ISO 3183 L450 pipe, which has a higher grade. API 5L X65 pipe is mainly used for the transportation of natural gas and oil. API 5L X65 pipe has a higher yield strength, and its minimum value is 450 MPa.

The specifications and properties of API 5L X65 PSL2 material meet the carbon steel standards. API 5L X65 PSL1 welded pipe provides a variety of pipe ends, such as plain end, threaded end and flare end. API 5L X65 high-yield pipe also includes straight-through-line (TFL) pipe, whose pipe ends are designed for special joints. API 5L Gr X65 HIC pipe does not accept rolled grades and rework. For sour service and higher pressures, the toughness of X65 steel pipes needs to be concerned. Therefore, toughness testing is often required.

Chemical Requirement for API 5L X65 Sour Service Pipe

Table H.1 ---Chemical composition for pipe with t ≤25,0 mm (0.984 in)

Steel grade	Mass fraction, based upon heat and product analyses % maximum									Carbon equivalent ^a % maximum
Steel grade	C ^b	Si	Mn ^b	P	S	V	Nb	Ti	Other ^{c, d}	CE _llw	CE _pcm
SMLS and welded Pipes
L245NS or BNS	0,14	0,40	1,35	0,020	0,003 ^e	f	f	0,04	g	0,36	0,19 ^h
L290NS or X65NS	o,14	0,40	1,35	0,020	0,003 ^e	0,05	0,05	0,04	-	0,36	0,19 ^h
L320NS or X65NS	0,14	0,40	1,40	0,020	0,003 ^e	0,07	0,05	0,04	g	0,38	0,20 ^h
L360NS or X65NS	0,16	0,45	1,65	0,020	0,003 ^e	0,10	0,05	0,04	g	0,43	0,22 ^h
L245QS or BQS	0,14	0,40	1,35	0,020	0,003 ^e	0,04	0,04	0,04	-	0,34	0,19 ^h
L 290QS or X65QS	0,14	0,40	1,35	0,020	0,003 ^e	0,04	0,04	0,04	-	0,34	0,19 ^h
L320QS or X65QS	0,15	0,45	1,40	0,020	0,003 ^e	0,05	0,05	0,04	-	0,36	0,20 ^h
L360QS or X65QS	0,16	0,45	1,65	0,020	0,003 ^e	0,07	0,05	0,04	g	0,39	0,20 ^h
L390QS or X65QS	0,16	0,45	1,65	0,020	0,003 ^e	0,07	0,05	0,04	g	0,40	0,21 ^h
L415QS or X65QS	0,16	0,45	1,65	0,020	0,003 ^e	0,08	0,05	0,04	g,i,k	0,41	0,22 ^h
L450QS or X65QS	0,16	0,45	1,65	0,020	0,003 ^e	0,09	0,05	0,06	g,i,k	0,42	0,22 ^h
L485QS or X70QS	0,16	0,45	1,65	0,020	0,003 ^e	0,09	0,05	0,06	g,i,k	0,42	0,22 ^h
welded pipe
L245MS or BMS	0,10	0,40	1,25	0,020	0,002 ^e	0,04	0,04	0,04	-	-	0,19
L290MS or X65MS	0,10	0,40	1,25	0,020	0,002 ^e	0,04	0,04	0,04	-	-	0,19
L320MS or X65 MS	0,10	0,45	1,35	0,020	0,002 ^e	0,05	0,05	0,04	-	-	0,20
L360MS or X65 MS	0,10	0,45	1,45	0,020	0,002 ^e	0,05	0,06	0,04	-	-	0,20
L390MS or X65 MS	0,10	0,45	1,45	0,020	0,002 ^e	0,06	0,08	0,04	g	-	0,21
L415MS or X65 MS	0,10	0,45	1,45	0,020	0,002 ^e	0,08	0,08	0,06	g,i	-	0,21
L450MS or X65MS	0,10	0,45	1,60	0,020	0,002 ^e	0,10	0,08	0,06	g,i,j	-	0,22
L485MS or X70 MS	0,10	0,45	1,60	0,020	0,002 ^e	0,10	0,08	0,06	g,i,j	-	0,22
a) Based upon product analysis (see 9.2.4 and 9.2.5) The CE_llw limits apply if the carbon mass fraction is greater than 0,12 % and the CE_pcmlimits apply if the carbon mass fraction is less than or equal to 0,12 %. b) for each reduction of 0,01 % below the specified maximum for carbon, an increase of 0,05 % above the specified maximum for manganese is permissible, up to a maximum increase of 0,20 %. c) AI _total≤ 0,060 %; N ≤ 0,012 %; AI/N ≥ 2:1 (not applicable to titanium-killed or titanium-treated steel); Cu ≤ 0,35 % (if agreed ,Cu ≤ 0,10 %); Ni ≤ 0,30 %; Cr ≤ 0,30 %; Mo ≤ 0,15 %; B ≤ 0,0005 %. d) for welded pipe where calcium is intentionally added, unless otherwise agreed, Ca/s ≥ 1,5 if S > 0,0015 % for SMLS and welded Pipes, the calcium concentration shall be ≤ 0,006 %. e) The maximum limit for sulfur concentration may be increased to ≤ 0,008 % for SMLS pipe and, if agreed, to ≤ 0,006 % for welded pipe. for such higher-sulfur levels in welded pipe, lower Ca/s ratios may be agreed. f) Unless otherwise agreed, the sum of the niobium and vanadium concentrations shall be ≤ 0,06 %. g) The sum of the niobium, vanadium and titanium concentrations shall be ≤ 0,15 %. h) for SMLS pipe, the listed value may be increased by 0,03. i) If agreed, the molybdenum concentration shall be ≤ 0,35 %. j) If agreed, the the chromium concentration shall be ≤ 0,45 %. k) If agreed, Cr concentration shall be ≤ 0,45 % and Ni concentration shall be ≤ 0,50 %.

Mechanical Requirement for API 5L X65 Sour Service Pipes

Table H.2 ----Requirements for the results of Tensile tests

Pipe steel grade	Pipe body of SMLS and welded Pipes						Weld seam of HFW and SAW Pipes
	Yield strength ^a R_to,5 Mpa (psi)		Tensile strength ^a R_m Mpa (psi)		Ratio^b R_to,5/R_m	Elongation on 50 mm or 2 in A_f %	Tensile strength ^c R_m Mpa (psi)
	minimum	maximum	minimum	maximum	maximum	minimum	minimum
L245NS or BNS L245QS or BQS L245MS or BMS	245 (35 500)	450 ^d (65 300) ^d	415 (60 200)	760 (110 200)	0,93	e	415 (60 200)
L290NS or X65NS L290QS or X65QS L290MS or X65MS	290 (42 100)	495 (71 800)	415 (60 200)	760 (110 200)	0,93	e	415 (60 200)
L320NS or X65NS L320QS or X65QS L320MS or X65MS	320 (52 400)	525 (76 100)	435 (63 100)	760 (110 200)	0,93	e	435 (63 100)
L360NS or X65NS L360QS or X65QS L360MS or X65MS	360 (52 200)	530 (76 900)	520 (66 700)	760 (110 200)	0,93	e	520 (66 700)
L390QS or X65QS L390MS or X65MS	390 (56 600)	545 (79 000)	490 (71 100)	760 (110 200)	0,93	e	490 (71 100)
L415QS or X65QS L415MS or X65MS	415 (60 200)	565 (81 900)	520 (75 400)	760 (110 200)	0,93	e	520 (75 400)
L450QS or X65QS L450MS or X65MS	450 (65 300)	600 (87 000)	535 (77 600)	760 (110 200)	0,93	e	535 (77 600)
L485MS or X70MS	485 (70 300)	635 (92 100)	570 (82 700)	760 (110 200)	0,93	e	570 (82 700)

Mechanical Requirement for API 5L X65 Sour Service Pipe

Table H.2 ----Requirements for the results of Tensile Tests

Pipe steel grade	Pipe body of SMLS and welded Pipes						Weld seam of HFW and SAW Pipes
	Yield strength ^a R_to,5 Mpa (psi)		Tensile strength ^a R_m Mpa (psi)		Ratio^b R_to,5/R_m	Elongation on 50 mm or 2 in A_f %	Tensile strength ^c R_m Mpa (psi)
	minimum	maximum	minimum	maximum	maximum	minimum	minimum
L245NS or BNS L245QS or BQS L245MS or BMS	245 (35 500)	450 ^d (65 300) ^d	415 (60 200)	760 (110 200)	0,93	e	415 (60 200)
L290NS or X65NS L290QS or X65QS L290MS or X65MS	290 (42 100)	495 (71 800)	415 (60 200)	760 (110 200)	0,93	e	415 (60 200)
L320NS or X65NS L320QS or X65QS L320MS or X65MS	320 (52 400)	525 (76 100)	435 (63 100)	760 (110 200)	0,93	e	435 (63 100)
L360NS or X65NS L360QS or X65QS L360MS or X65MS	360 (52 200)	530 (76 900)	520 (66 700)	760 (110 200)	0,93	e	520 (66 700)
L390QS or X65QS L390MS or X65MS	390 (56 600)	545 (79 000)	490 (71 100)	760 (110 200)	0,93	e	490 (71 100)
L415QS or X65QS L415MS or X65MS	415 (60 200)	565 (81 900)	520 (75 400)	760 (110 200)	0,93	e	520 (75 400)
L450QS or X65QS L450MS or X65MS	450 (65 300)	600 (87 000)	535 (77 600)	760 (110 200)	0,93	e	535 (77 600)
L485MS or X70MS	485 (70 300)	635 (92 100)	570 (82 700)	760 (110 200)	0,93	e	570 (82 700)

a for intermediate grades, the difference between the specified maximum yield strength and the specified minimum yield strength shall be as given in the table for the next higher grade, and the difference between the specified minimum tensile strength and the specified minimum yield strength shall be as given in the table for the next higher grade, for intermediate grades, the tensile strength shall be ≤ 760 MPa (110 200 psi).

b This limit applies for pipe with D >323, 9 mm (12.750 in).

c 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 footnote a).

d for pipe with D< 219,1 mm (8.625 in), the maximum yield strength shall be ≤495 MPa (71 800 psi).

e The specified minimum elongation, A_f, on 50mm or 2 in, expressed in percent and rounded to the nearest percent, shall be as determined using the following equation:

api5l pipe elongation values

Where

C is 1 940 for calculations using SI units and 625 000 for calculations using USC units;

A_xc is the applicable tensile test piece cross-sectional area, expressed in square millimeters (square inches), as follows:

---- for circular cross-section test pieces, 130 mm² (0.20 in²) for 12,5 mm (0.500 in) and 8,9 mm (0.350 in) diameter test pieces; and 65 mm² ( 0.10 in²) for 6,4 mm (0.250 in) 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 (0.01 in²)

---- 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 (0.01 in²);