What is API 5CT Casing & Tubing

API 5CT (American Petroleum Institute Casing and Tubing Specification) is a globally accepted seamless steel pipe technical standard in the oil and gas industry. Its core characteristics include high crush strength, corrosion resistance, and good weldability. These steel pipes are widely used in oil and gas well casing, tubing, and deep well drilling.

What is Specification of API 5CT Casing & Tubing

OD: 4 1/2'' ~ 20'' (114.3mm ~ 508mm)

WT: 0.205'' ~ 0.635'' (5.21mm ~ 16.13mm)

LENGTH: R1, R2, R3

Standard: API 5CT J 55/K55/N80/C75/L80/C90/T95/Q125

Process Type: Seamless (SMLS), Electric Resistance Welded (ERW)

End: Beveled, Square Cut, With LTC/STC/BTC/VAM Connection

Surface: Anti-corrosion Water Based Paint

Packing: Protection Caps in both end, Waterproof Paper Wrapped, Two Tags

What is Tolerance of API 5CT OCTG

Types of steel tubes	Outer Diameter		Wall Thickness
Cold-rolled tubes	Tube sizes(mm)	Tolerances(mm)	Tolerances(mm)
	＜114.3	±0.79	－12.5%

What is Chemical Composition of API 5CT Casing and Tubing

Standard	Grade	Chemical compositions(％)
API SPEC 5CT	J55	C	Si	Mn	P	S	Cr	Ni	Cu	Mo	V
	K55	0.34～0.39	0.20～0.35	1.25～1.50	≤0.020	≤0.015	≤0.15	≤0.20	≤0.20	/	/
	N80	0.34～0.38	0.20～0.35	1.45～1.70	≤0.020	≤0.015	≤0.15	/	/	/	0.11～0.16
	L80	0.15～0.22	≤1.00	0.25～1.00	≤0.020	≤0.010	12.0～14.0	≤0.20	≤0.20	/	/
	P110	0.26～0.395	0.17～0.37	0.40～0.70	≤0.020	≤0.010	0.80～1.10	≤0.20	≤0.20	0.15～0.25	≤0.08

What is Mechanical Properties of API 5CT

Grade	Type	Total elongation under load (%)	Yield strength (min)	Yield strength (max)	Tensile strength min Mpa	Hardness Max (HRC)	Hardness Max(HBW)
J55	-	0.5	379	552	517	-	-
K55	-	0.5	379	552	655	-	-
N80	1	0.5	552	758	689	-	-
N80	Q	0.5	552	758	689	-	-
L80	1	0.5	552	655	655	23	241
L80	9Cr	0.5	552	655	655	23	241
L80	13Cr	0.5	552	655	655	23	241
C90	-	0.5	621	724	689	25.4	255
C95	-	0.5	655	758	724	-	-
T95	-	0.5	655	758	724	25.4	255
P110	-	0.6	758	965	862	-	-
Q125	All	0.65	862	1034	931	-	-

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