Seamless Casing, API Steel Casing Pipe

There are two main types of API oil casing according to the different manufacturing methods: Seamless Casing and ERW Casing. Today we mainly discuss seamless casing.

Seamless Casing - Casing made of seamless steel pipe as raw material;

Seamless steel pipe refers to steel pipe manufactured by four methods: hot rolling, cold rolling, hot drawing and cold drawing. There is no weld on the pipe body itself.

Casing and Tubing:
Casing and tubing play an important role in oil and gas exploration and production. The casing constitutes the well wall and is a permanent structure, while the tubing is located inside the casing, and the oil or gas is transported to the ground through the casing. Both are key components of oil or gas wells, as failure will result in huge losses. As the depth of the well increases, the requirements will be very strict. Sometimes the well must pass through the rock layer, and sometimes it is in the sea. The size, grade and number of pipes depend on the design of the well, which is based on the product, depth, pressure, volume and environment. As most of the easy exploration areas are exhausted and exploration enters difficult areas, the demand for higher grade and higher quality pipes is increasing every year.

Manufacturing process of seamless casing:
Seamless casing and connections are considered the most commonly used oilfield casing today. Seamless casing is produced by perforation using solid steel billets in a pipe plant.

The manufacturing process of seamless casing includes exposing the billet to high temperatures; using a mandrel to penetrate the billet; feeding the billet to rollers and an internal mandrel to set the shape; heat treating the tube; straightening and final sizing.

Features of seamless casing and connections:
The size and wall thickness specifications of oil well seamless casing range from 1/8 inch to 26 inch OD. It is particularly suitable for high-pressure operations, including oil and gas exploration and drilling, hydrocarbon industries and refineries, and oil and gas transportation.

The threads of seamless casing connections can be completed by the manufacturer or other companies. Ensuring uniform wall thickness of seamless casing is a challenge for manufacturers. The production process may cause the cross-section of the seamless casing wall to be slightly eccentric.

Seamless casing and connections are better than welded types:

Seamless casing and connections are better than welded types. The main advantage of seamless oil well casing is the absence of welds, which are considered weak points that can cause failure and corrosion risks. In addition, seamless casing and connections have better roundness. Finally, the possibility of weak seams is eliminated.

The only weaknesses of seamless casing and oil well connections are wall thickness differences, challenges in the production process, and higher costs. Click "Seamless casing vs ERW casing" for more information.

Seamless Casing Pipe Specifications & Sizes Chart:

Outside Diameter		Nominal Weight		Wall Thickness		Grade and Connection Type*
in.	mm	lb/ft	kg/m	in.	mm	J55 K55	M65	L80 C95	N80	C90 T95	P110
4-1/2	114.30	9.50	14.14	0.205	5.21	PS	PS	-	-	-	-
		10.50	15.63	0.224	5.69	PSB	PSB	-	-	-	-
		11.60	17.26	0.250	6.35	PSLB	PLB	PLB	PLB	PLB	PLB
		13.50	20.09	0.290	7.37	-	PLB	PLB	PLB	PLB	PLB
		15.10	22.47	0.337	8.56	-	-	-	-	-	PLB
5	127.00	11.50	17.11	0.220	5.59	PS	PS	-	-	-	-
		13	19.35	0.253	6.43	PSL	PSLB	-	-	-	-
		15.00	22.32	0.296	7.52	PSLB	PLB	PSLB	PSLB	PSLB	PSLB
		18.00	26.79	0.362	9.19	-	PLB	PSLB	PSLB	PSLB	PSLB
		21.40	31.85	0.437	11.10	-	PLB	PLB	PLB	PLB	PLB
		23.20	34.53	0.478	12.14	-	-	PLB	PLB	PLB	PLB
		24.10	35.86	0.500	12.70	-	-	PLB	PLB	PLB	PLB
5-1/2	139.70	14.00	20.83	0.244	6.20	PS	PS	-	-	-	-
		15.50	23.07	0.275	6.98	PSLB	PSLB	-	-	-	-
		17.00	25.30	0.304	7.72	PSLB	PLB	PSLB	PSLB	PLB	PSLB
		20.00	29.76	0.361	9.17	-	PLB	PSLB	PSLB	PLB	PSLB
		23.00	34.23	0.415	10.54	-	PLB	PSLB	PSLB	PLB	PSLB
6-5/8	168.28	20.00	29.76	0.288	7.32	PSLB	PSLB	-	-	-	-
		24.00	35.72	0.352	8.94	PSLB	PLB	PSLB	PSLB	PSLB	PSLB
		28.00	41.67	0.417	10.59	-	PLB	PSLB	PSLB	PSLB	PSLB
		32.00	47.62	0.475	12.06	-	-	PSLB	PSLB	PSLB	PSLB
7	177.80	20.00	29.76	0.272	6.91	PS	PS	-	-	-	-
		23.00	34.23	0.317	8.05	PSLB	PLB	PSLB	PSLB	PLB	-
		26.00	38.69	0.362	9.19	PSLB	PLB	PSLB	PSLB	PLB	PSLB
		29.00	43.16	0.408	10.36	-	PLB	PSLB	PSLB	PLB	PSLB
		32.00	47.62	0.453	11.51	-	PLB	PSLB	PSLB	PLB	PSLB
		35.00	52.13	0.498	12.65	-	-	PSLB	PSLB	PLB	PSLB
		38.00	56.60	0.540	13.72	-	-	PSLB	PSLB	PLB	PSLB
7-5/8	193.68	26.40	39.29	0.328	8.33	PSLB	PSLB	PLB	PLB	PLB	-
		29.70	44.20	0.375	9.52	-	PLB	PLB	PLB	PLB	PLB
		33.70	50.15	0.430	10.92	-	PLB	PLB	PLB	PLB	PLB
		39.00	58.05	0.500	12.70	-	-	PLB	PLB	PLB	PLB
		42.80	63.69	0.562	14.27	-	-	PLB	PLB	PLB	PLB
		45.30	67.41	0.595	15.11	-	-	PLB	PLB	PLB	PLB
		47.10	70.09	0.625	15.88	-	-	PLB	PLB	PLB	PLB
8-5/8	219.08	24.00	36.75	0.264	6.71	PS	PS	-	-	-	-
		28.00	41.67	0.304	7.72	-	PS	-	-	-	-
		32.00	47.66	0.352	8.94	PSLB	PSLB	-	-	-	-
		36.00	53.62	0.400	10.16	PSLB	PSLB	PLB	PLB	PLB	-
		40.00	59.58	0.450	11.43	-	PLB	PLB	PLB	PLB	PLB
		44.00	65.54	0.500	12.70	-	-	PLB	PLB	PLB	PLB
		49.00	72.99	0.557	14.15	-	-	PLB	PLB	PLB	PLB
9-5/8	244.48	36.00	53.57	0.352	8.94	PSLB	PSLB	-	-	-	-
		40.00	59.53	0.395	10.03	PSLB	PSLB	PLB	PLB	PLB	-
		43.50	64.73	0.435	11.05	-	PLB	PLB	PLB	PLB	PLB
		47.00	69.94	0.472	11.99	-	PLB	PLB	PLB	PLB	PLB
		53.50	79.62	0.545	13.84	-	-	PLB	PLB	PLB	PLB
		58.40	86.91	0.595	15.11	-	-	PLB	PLB	PLB	PLB
10-3/4	273.05	40.50	60.32	0.350	8.89	PSB	PSB	PLB	PLB	PLB	PLB
		45.50	67.78	0.400	10.16	PSB	PSB	-	-	-	-
		51.00	75.96	0.450	11.43	PSB	PSB	PSB	PSB	PSB	PSB
		55.50	72.67	0.495	12.57	-	PSB	PSB	PSB	PSB	PSB
		60.70	90.41	0.545	13.84	-	-	-	-	PSB	PSB
		65.70	97.86	0.595	15.11	-	-	-	-	PSB	PSB
13-3/8	339.70	54.50	81.18	0.380	9.65	PSB	PSB	-	-	PSB	PSB
		61.00	90.86	0.430	10.92	PSB	PSB	-	-	-	-
		68.00	101.29	0.480	12.19	PSB	PSB	PSB	PSB	PSB	PSB
		72.00	107.24	0.514	13.06	-	-	-	-	PSB	PSB
20	508.00	94.00	139.89	0.438	11.13	SLB	SLB	-	-	-	-
		106.50	158.49	0.500	12.70	SLB	SLB	-	-	-	-
		133.00	197.93	0.635	16.13	SLB	-	-	-	-	-

* Premium connections are available on request. P - plain end, S - short round thread, B - butress, L - long round thread.

Read more: Steel Grade of Casing Pipe or Casing pipe vs Drill pipe