overview of  API 5ct J55, K55, N80, L80, T95, P110, Q125 Oil Casing grades

API 5CT j55, K55, N80, L80, T95, P110, and Q125 are oil casing grades that are widely used in the Oil and gas industry. These grades are defined by the American petroleum Institute (API) and are designed to meet specific requirements for oil and gas well construction. Silicone TubeJ55 is a commonly used grade that has a minimum yield strength of 55,000 psi. It is suitable for shallow to medium-depth wells and is often used in Casing strings that are not subjected to high internal pressures. K55 is similar to J55 in terms of its yield strength but has a higher tensile strength. This makes it more suitable for wells that require higher pressure containment.

Labels		Outside diameter (d/mm)	T&C (kg/m)	Wall thickness   (t/mm)	type of end-finish
1	2				J55/K55	M65	L80/ R95	N80-1/Q	C90/T95	P110	Q125
4-1/2	9.50	114.30	14.14	5.21	PS	PS	–	–	–	–	–
	10.50	114.30	15.63	5.69	PSB	PSB	–	–	–	–	–
	11.60	114.30	17.26	6.35	PSLB	PLB	PLB	PLB	PLB	PLB	–
	13.50	114.30	20.09	7.37	–	PLB	PLB	PLB	PLB	PLB	–
	15.10	114.30	22.47	8.56	–	–	–	–	–	PLB	PLB
5	11.50	127.00	17.11	5.59	PS	PS	–	–	–	–	–
	13.00	127.00	19.35	6.43	PSLB	PSLB	–	–	–	–	–
	15.00	127.00	22.32	7.52	PSLB	PLB	SLB	PLB	PLB	PLB
	18.00	127.00	26.79	9.19	–	PLB	SLB	PLB	PLB	PLB	PLB
	21.40	127.00	31.85	11.10	–	PLB	PLB	PLB	PLB	PLB	PLB
	23.20	127.00	34.53	12.14	–	–	PLB	PLB	PLB	PLB	PLB
	24.10	127.00	35.87	12.70	–	–	PLB	PLB	PLB	PLB	PLB
5-1/2	14.00	139.70	20.83	6.20	PS	PS	–	–	–	–	–
	15.50	139.70	23.07	6.98	PSLB	PSLB	–	–	–	–	–
	17.00	139.70	25.30	7.72	PSLB	PLB	PLB	PLB	PLB	PLB	–
	20.00	139.70	29.76	9.17	–	PLB	PLB	PLB	PLB	PLB	–
	23.00	139.70	34.23	10.54	–	PLB	PLB	PLB	PLB	PLB	PLB
	26.80	139.70	39.88	12.70	–	–	–	–	P	–	–
	29.70	139.70	44.20	14.27	–	–	–	–	P	–	–
	32.60	139.70	48.52	15.88	–	–	–	–	P	–	–
	35.30	139.70	52.53	17.45	–	–	–	–	P	–	–
	38.00	139.70	56.55	19.05	–	–	–	–	P	–	–
	40.50	139.70	60.27	20.62	–	–	–	–	P	–	–
	43.10	139.70	64.14	22.22	–	–	–	–	P	–	–
6-5/8	20.00	168.28	29.76	7.32	PSLB	PSLB	–	–	–	–	–
	24.00	168.28	35.72	8.94	PSLB	PLB	PLB	PLB	PLB	PLB	–
	28.00	168.28	41.67	10.59	–	PLB	PLB	PLB	PLB	PLB	–
	32.00	168.28	47.62	12.06	–	–	PLB	PLB	PLB	PLB	PLB
7	17.00	177.80	25.30	5.87	–	–	–	–	–	–	–
	20.00	177.80	29.76	6.91	PS	PS	–	–	–	–	–
	23.00	177.80	34.23	8.05	PSLB	PLB	PLB	PLB	PLB	–	–
	26.00	177.80	38.69	9.19	–	PLB	PLB	PLB	PLB	PLB	–
	29.00	177.80	43.16	10.36	–	PLB	PLB	PLB	PLB	PLB	–
	32.00	177.80	47.62	11.51	–	PLB	PLB	PLB	PLB	PLB	–
	35.00	177.80	52.09	12.65	–	–	PLB	PLB	PLB	PLB	PLB
	38.00	177.80	56.55	13.72	–	–	PLB	PLB	PLB	PLB	PLB
	42.70	177.80	63.55	15.88	–	–	–	–	P	–	–
	46.40	177.80	69.05	17.45	–	–	–	–	P	–	–
	50.10	177.80	74.56	19.05	–	–	–	–	P	–	–
	53.60	177.80	79.77	20.62	–	–	–	–	P	–	–
	57.10	177.80	84.98	22.22	–	–	–	–	P	–	–
7-5/8	24.00	193.68	35.72	7.62	–	–	–	–		–	–
	26.40	193.68	39.29	8.33	PSLB	PSLB	PLB	PLB	PLB	–	–
	29.70	193.68	44.20	9.52	–	PLB	PLB	PLB	PLB	PLB	–
	33.70	193.68	50.15	10.92	–	PLB	PLB	PLB	PLB	PLB	–
	39.00	193.68	58.04	12.70	–	–	PLB	PLB	PLB	PLB	PLB
	42.80	193.68	63.69	14.27	–	–	PLB	PLB	PLB	PLB	PLB
	45.30	193.68	67.42	15.11	–	–	PLB	PLB	PLB	PLB	PLB
	47.10	193.68	70.09	15.88	–	–	PLB	PLB	PLB	PLB	PLB
	51.20	193.68	76.20	17.45	–	–	–	–	P	–	–
	55.30	193.68	82.30	19.05	–	–	–	–	P	–	–
7-3/4	46.10	196.85	68.61	15.11	–	–	P	P	P	P	P
8-5/8	24.00	219.08	35.72	6.71	PS	PS	–	–	–	–	–
	28.00	219.08	41.67	7.72		PS	–	–	–	–	–
	32.00	219.08	47.62	8.94	PSLB	PSLB	–	–	–	–	–
	36.00	219.08	53.58	10.16	PSLB	PSLB	PLB	PLB	PLB	PLB	–
	40.00	219.08	59.53	11.43	–	PLB	PLB	PLB	PLB	PLB	–
	44.00	219.08	65.48	12.70	–	–	PLB	PLB	PLB	PLB	–
	49.00	219.08	72.92	14.15	–	–	PLB	PLB	PLB	PLB	PLB
9-5/8	32.30	244.48	48.07	7.92	–	–	–	–	–	–	–
	36.00	244.48	53.58	8.94	PSLB	PSLB	–	–	–	–	–
	40.00	244.48	59.53	10.03	PSLB	PSLB	PLB	PLB	PLB	–	–
	43.50	244.48	64.74	11.05	–	PLB	PLB	PLB	PLB	PLB	–
	47.00	244.48	69.95	11.99	–	PLB	PLB	PLB	PLB	PLB	PLB
	53.50	244.48	79.62	13.84	–	–	PLB	PLB	PLB	PLB	PLB
	58.40	244.48	86.91	15.11	–	–	PLB	PLB	PLB	PLB	PLB
	59.40	244.48	88.40	15.47	–	–	–	–	P	–	–
	64.90	244.48	96.58	17.07	–	–	–	–	P	–	–
	70.30	244.48	104.62	18.64	–	–	–	–	P	–	–
	75.60	244.48	112.51	20.24	–	–	–	–	P	–	–
10-3/4	32.75	273.05	48.74	7.09	–	–	–	–	–	–	–
	40.50	273.05	60.27	8.89	PSB	PSB	–	–	–	–	–
	45.50	273.05	67.71	10.16	PSB	PSB	–	–	–	–	–
	51.00	273.05	75.90	11.43	PSB	PSB	PSB	PSB	PSB	PSB	–
	55.50	273.05	82.60	12.57	–	PSB	PSB	PSB	PSB	PSB	–
	60.70	273.05	90.33	13.84	–	–	–	–	PSB	PSB	PSB
	65.70	273.05	97.77	15.11	–	–	–	–	PSB	PSB	PSB
	73.20	273.05	108.94	17.07	–	–	–	–	P	–	–
	79.20	273.05	117.87	18.64	–	–	–	–	P	–	–
	85.30	273.05	126.94	20.24	–	–	–	–	P	–	–
11-3/4	42.00	298.45	62.50	8.46	–	–	–	–	–	–	–
	47.00	298.45	69.95	9.53	PSB	PSB	–	–	–	–	–
	54.00	298.45	80.36	11.05	PSB	PSB	–	–	–	–	–
	60.00	298.45	89.29	12.42	PSB	PSB	PSB	PSB	PSB	PSB	PSB
	65.00	298.45	96.73	13.56	–	–	P	P	P	P	P
	71.00	298.45	105.66	14.78	–	–	P	P	P	P	P
13-3/8	48.00	339.72	71.43	8.38	–	–	–	–	–	–	–
	54.50	339.72	81.11	9.65	PSB	PSB	–	–	–	–	–
	61.00	339.72	90.78	10.92	PSB	PSB	–	–	–	–	–
	68.00	339.72	101.20	12.19	PSB	PSB	PSB	PSB	PSB	PSB	–
	72.00	339.72	107.15	13.06	–	–	PSB	PSB	PSB	PSB	PSB
16	65.00	406.40	96.73	9.53	–	–	–	–	–	–	–
	75.00	406.40	111.62	11.13	PSB	PSB	–	–	–	–	–
	84.00	406.40	125.01	12.57	PSB	PSB	–	–	–	–	–
	109.00	406.40	162.21	16.66	P	–	P	P	–	P	P
18-5/8	87.50	473.08	130.22	11.05	PSB	PSB	–	–	–	–	–
20	94.00	508.00	139.89	11.13	PSLB	PSLB	–	–	–	–	–
	106.50	508.00	158.49	12.70	PSLB	PSLB	–	–	–	–	–
	133.00	508.00	197.93	16.13	PSLB	–	–	–	–	–	–

N80 is a higher strength grade with a minimum yield strength of 80,000 psi. It is commonly used in medium to deep wells and is known for its excellent resistance to corrosion. L80 is another high-strength grade that has a minimum yield strength of 80,000 psi. It is often used in wells that have high internal pressures or are subjected to sour service conditions. T95 is a higher strength grade with a minimum yield strength of 95,000 psi. It is commonly used in deep wells that require high pressure containment. It is also known for its resistance to sulfide stress cracking. P110 is a high-strength grade with a minimum yield strength of 110,000 psi. It is commonly used in deep wells that require high pressure containment and is known for its excellent resistance to corrosion. Q125 is the highest strength grade in the API 5CT specification, with a minimum yield strength of 125,000 psi. It is commonly used in deep wells that require high pressure containment and is known for its excellent resistance to corrosion and sulfide stress cracking. These oil casing grades are manufactured using a variety of processes, including seamless and electric resistance welding (erw). seamless casing is produced by piercing a solid billet of steel and then rolling it into a seamless tube. This process ensures a uniform wall thickness and excellent mechanical properties. erw casing, on the other hand, is produced by forming a strip of steel into a tube and then welding the edges together. This process is more cost–effective but may result in slightly lower mechanical properties compared to seamless casing.

In addition to the mechanical properties, these oil casing grades also have specific chemical composition requirements. This ensures that the casing has the necessary strength and Corrosion resistance to withstand the harsh conditions