Products Seamless Pipe

Seamless steel pipe is a hollow tubular material formed in a single process through piercing, rolling, or extrusion from a round billet, resulting in a seamless, weld-free structure. Materials include stainless steel, carbon steel, duplex steel, super duplex steel, and nickel alloys. The absence of welds ensures greater uniformity and stability throughout the pipe, delivering higher strength and superior fatigue resistance to withstand greater internal and external pressures.

Their surfaces are smooth and continuous, with precise dimensions, ensuring extended service life in high-temperature, high-pressure, high-stress, and corrosive environments. Consequently, they are widely used in petroleum drilling and extraction, boiler heat exchange, mechanical equipment, energy transmission, and chemical processing equipment, serving as indispensable key components in numerous industrial systems.

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JINIE Seamless Pipe Specifications

JN is a Chinese steel pipe manufacturer with over 20 years of experience. Our steel pipe production strictly adheres to international standards, including ASTM, ASME, JIS, GOST, DIN, and others. The following lists only a portion of the sizes we produce. To view the complete list of standards, please visit our Products and Standards page or send us an email for inquiries.

ASME B36.10：Specification for welded and seamless wrought steel pipe for high or low temperature and pressures

DN	NPS	OD	Sch10	Sch20	Sch30	Sch40	STD	Sch60	Sch80	XS	Sch100	Sch120	Sch140	Sch160	XXS
6	1/8	10.3	1.24		1.45	1.73	1.73		2.41	2.41
8	1/4	13.7	1.65		1.85	2.24	2.24		3.02	3.02
10	3/8	17.1	1.65		1.85	2.31	2.31		3.2	3.2
15	1/2	21.3	2.11		2.41	2.77	2.77		3.73	3.73				4.78	7.47
20	3/4	26.7	2.11		2.41	2.87	2.87		3.91	3.91				5.56	7.82
25	1	33.4	2.77		2.90	3.38	3.38		4.55	4.55				6.35	9.09
32	1 1/4	42.2	2.77		2.97	3.56	3.56		4.85	4.85				6.35	9.7
40	1 1/2	48.3	2.77		3.18	3.68	3.68		5.08	5.08				7.14	10.15
50	2	60.3	2.77		3.18	3.91	3.91		5.54	5.54				8.74	11.07
65	2 1/2	73	3.05		4.78	5.16	5.16		7.01	7.01				9.53	14.02
80	3	88.9	3.05		4.78	5.49	5.49		7.62	7.62				11.13	15.24
90	3 1/2	101.6	3.05		4.78	5.74	5.74		8.08	8.08
100	4	114.3	3.05		4.78	6.02	6.02		8.56	8.56		11.13		13.49	17.12
125	5	141.3	3.40			6.55	6.55		9.53	9.53		12.7		15.88	19.05
150	6	168.3	3.40			7.11	7.11		10.97	10.97		14.27		18.26	21.95
200	8	219.1	3.76	6.35	7.04	8.18	8.18	10.31	12.70	12.70	15.09	18.26	20.62	23.01	22.23
250	10	273.1	4.19	6.35	7.8	9.27	9.27	12.7	15.09	12.70	18.26	21.44	25.4	28.58	25.40
300	12	323.9	4.57	6.35	8.38	10.31	9.53	14.27	17.48	12.70	21.44	25.4	28.58	33.32	25.40
350	14	355.6	6.35	7.92	9.53	11.13	9.53	15.09	19.05	12.70	23.83	27.79	31.75	35.71
400	16	406.4	6.35	7.92	9.53	12.70	9.53	16.66	21.44	12.70	26.19	30.96	36.53	40.49
450	18	457	6.35	7.92	11.13	14.27	9.53	19.05	23.83	12.70	29.36	34.93	39.67	45.24
500	20	508	6.35	9.53	12.70	15.09	9.53	20.62	26.19	12.70	32.54	38.1	44.45	50.01
550	22	559	6.35	9.53	12.70		9.53	22.23	28.58	12.70	34.93	41.28	47.63	53.98
600	24	610	6.35	9.53	14.27	17.48	9.53	24.61	30.96	12.70	38.89	46.02	52.37	59.54
650	26	660	7.92	12.7			9.53			12.70
700	28	711	7.92	12.7	15.88		9.53			12.70
750	30	762	7.92	12.7	15.88		9.53			12.70
800	32	812.8	7.92	12.7	15.88	17.48	9.53			12.70
850	34	863.6	7.92	12.7	15.88	17.48	9.53			12.70
900	36	914.4	7.92	12.7	15.88	19.05	9.53			12.70
	38	965.2					9.53			12.70
1000	40	1016					9.53			12.70
1050	42	1066.8					9.53			12.70
1100	44	1117.6					9.53			12.70
	46	1168.4					9.53			12.70
1200	48	1219.2					9.53			12.70

Seamless steel pipe dimensional parameters include nominal outer diameter, wall thickness, inner diameter, length, bevel angle, material grade, production standards, and quantity. JN seamless pipe suppliers can customize according to your requirements, whether for piping or prefabricated welded structural components.

Among these, nominal outside diameter and wall thickness are the two most critical parameters in seamless pipe sizing. Wall thickness, in particular, is the core data for calculating a pipe's pressure-bearing capacity. According to specifications like ASME or API, a pipe's pressure rating directly depends on the material's minimum yield strength, outside diameter, and minimum wall thickness. If the actual wall thickness falls below the lower tolerance limit, it will lead to pipe failure and rupture.

Nominal outside diameter is also a parameter determining a pipe's pressure-bearing capacity, and its deviation can affect pressure distribution.

Common wall thickness specifications can be divided into the following three types:

Thin-walled seamless steel pipe: usually 1 mm to 4 mm.

Medium thickness seamless steel pipe: usually 5 mm to 10 mm.

Thick-wall seamless steel pipe: usually 12 mm to 30 mm, or 30 mm and above.

JINIE Seamless Pipe Standard

The most widely adopted production standards for seamless steel pipes are those established by the United States, Europe, and international bodies.

Common seamless pipe production standards include: ASTM A106, ASTM A53, ASTM A213, ASTM A53, ASTM A179, ASTM A333, and others.

JN Seamless Pipe Manufacturing Process

Seamless Pipe Types

Seamless steel pipes can be divided into many types according to their manufacturing process, materials and uses.

1. Classification by Manufacturing Process

Hot-rolled Seamless Steel Pipe

Hot-rolled seamless pipe is a steel pipe produced using the hot rolling process. The basic process involves heating a solid billet, passing it through a piercing mill to form a rough tube, and then rolling it down to the desired dimensions using equipment such as a continuous rolling mill or a cyclic rolling mill.

However, hot-rolled pipes exhibit surface oxide scale, resulting in relatively low dimensional accuracy and surface finish. Therefore, they are often used as billets for subsequent cold working or directly in structural transportation applications where dimensional accuracy is less critical, such as general fluid transportation and structural support.

Cold-rolled/Cold-drawn Seamless Steel Pipe

Cold-drawn seamless pipes are further processed from hot-rolled billets through a cold drawing or cold rolling process at room temperature.

The cold working process induces work hardening, significantly increasing the strength and hardness of the steel pipe while achieving extremely high dimensional accuracy and excellent surface finish.

Cold-drawn pipes offer uniform wall thickness and excellent surface quality, making them ideal for applications such as precision mechanical structures, hydraulic, and pneumatic cylinders. In order to ensure that its mechanical properties meet the requirements of use, stress relief annealing or full annealing treatment is usually required after cold drawing.

2. Classification by Material

Carbon Steel Seamless Pipe

This type of steel pipe is primarily made of carbon steel, with typical grades such as 20 steel and 45 steel. They offer excellent strength, ductility, and weldability, and are relatively low cost, making them the most widely used seamless steel pipe.

Common standards include GB/T 8162 and GB/T 8163. They are widely used in building structural supports, general mechanical components, and pipelines for transporting fluids such as water, oil, and steam in non-corrosive environments.

Alloy Steel Seamless Pipe

Alloy steel seamless pipe is a carbon steel pipe with specific properties achieved by adding one or more alloying elements.

Among them, chromium-molybdenum steel is the most widely used type, with typical grades such as 15CrMoG and P91. The addition of alloying elements significantly improves the steel pipe's strength, toughness, wear resistance, and high-temperature performance, enabling it to operate under high temperatures and high pressures for long periods without creep failure.

Therefore, it is primarily used in superheaters and reheaters in power plant boilers, hydrogenation reactors in the petrochemical industry, and key piping in high-pressure boiler equipment.

Stainless Steel Seamless Pipe

Stainless steel seamless pipes are primarily characterized by corrosion resistance. Their primary alloying elements are high levels of chromium and nickel.

Based on their metallographic structure, they can be classified as austenitic, ferritic, martensitic, and duplex stainless steels. They resist corrosion from a variety of media, including atmospheric, acidic, alkaline, and salty media.

Among them, austenitic stainless steel pipes are the most widely used, while grades like 316L, which have added molybdenum, are even more resistant to chloride pitting. They are widely used in applications such as food processing, pharmaceuticals, chemical equipment, shipbuilding, and the nuclear industry, where cleanliness and corrosion resistance are paramount.

Nickel Alloy Seamless Steel Pipe

Nickel-based alloy seamless steel pipes are used when the operating environment is extremely harsh and exceeds the tolerances of stainless steel.

Nickel alloy SMLS pipes, such as Hastelloy and Inconel, are primarily composed of nickel and contain significant amounts of elements such as chromium, molybdenum, and niobium. They offer excellent corrosion resistance, including resistance to highly corrosive media like hot concentrated acids and wet chlorine gas, while also possessing excellent high-temperature strength and oxidation resistance.

It is mainly used in marine engineering, flue gas desulfurization systems, chemical processes in high-temperature corrosive environments, and high-temperature components of aerospace engines.

3. Classification by Special Application

Boiler Tubes

Boiler tubes are a specialized category, encompassing both high-pressure and low-pressure boiler tubes. They have extremely stringent requirements for steel quality, chemical composition, mechanical properties, and processability, ensuring safe operation under the long-term effects of high temperatures, high pressures, and corrosive media.

Standards such as GB 5310 and GB 3087 require rigorous process tests, including flattening, flaring, and crimping, to ensure sufficient strength and ductility.

Oil Pipes

These are seamless steel pipes used in oil and natural gas drilling and production, primarily including drill pipe, casing, and tubing.

This type of steel pipe faces extremely complex operating conditions, enduring the combined stresses of tension, compression, bending, and torsion, as well as corrosive wear from mud. Therefore, they require extremely high strength, toughness, collapse resistance, and resistance to threaded connection failure.

They are typically produced according to American Petroleum Institute (API) standards, such as API 5CT and API 5D, and utilize a significant amount of alloy steel to meet high-strength grade requirements.

Precision Seamless Steel Tube for Hydraulic and Pneumatic Cylinders

This type of steel tube is a top-quality cold-drawn seamless steel tube, specifically used for manufacturing cylinder barrels for hydraulic and pneumatic cylinders.

It has stringent requirements for the inner bore's surface roughness, dimensional tolerances, straightness, and roundness to ensure long-term, reliable seal operation and smooth piston movement.

Precision machining of the inner and outer surfaces is typically performed using processes such as precision reaming or cold rolling to achieve a mirror-like finish and extremely high dimensional consistency.

Bearing Steel Tube

Bearing steel tube is a specialized tube used in the manufacture of rolling bearing rings. Common grades include GCr15.

Extremely high standards are imposed on material purity, chemical composition uniformity, non-metallic inclusion content and distribution, and decarburization depth. The steel tube is required to exhibit high and uniform hardness, wear resistance, and contact fatigue life.

The manufacture of bearing steel tubes requires rigorous refining and controlled rolling and cooling processes to ensure a dense and uniform internal structure.