Stainless steel pipes/piping Manufacturers&Suppliers In China


As many people think, The stainless steel pipe is the same as the stainless steel tube, however, there is a big difference in the strict sense. We will introduce what the difference is.


What are stainless steel pipes?  


Stainless steel pipe is a kind of hollow long round stainless steel, the pipe is a round hollow section for the conveyance of products. The products include fluids, gas, pellets, powders, and more. It is mainly widely used in petroleum, chemical, medical, food, light industry, mechanical instrumentation, other industrial transmission pipelines, and mechanical structural components, etc.

In addition, in the bending, torsion strength of the same, lighter weight, so also widely used in the manufacture of mechanical parts and engineering structures. 

Where both ends open and has a hollow section, and its length and section perimeter are large stainless steel, can be called stainless steel pipe. When the length and section circumference is small, it can be called pipe section or pipe fittings, they all belong to the category of pipe products.


What are stainless steel tubes?

The stainless steel tubes is a kind of hollow long stainless steel. The shape can be round, square, rectangular, oval, hexagonal, etc. In some sense, stainless steel tube is an unnormal shape pipe, It also includes round. The tube is widely used in various structural parts, tools, and mechanical parts. building materials, etc. It is also commonly used for furniture, kitchenware, doors, and windows,  stair railings, etc. It is very common in daily life.


What difference between stainless steel pipe and stainless steel tube?


A stainless steel pipe is a round tubular to transporting liquids and gases, designated by a nominal pipe size (NPS or DN) that represents a rough indication of the pipe conveyance capacity.

The most important dimensions for a pipe are the outside diameter (OD) together with the wall thickness (WT). OD minus 2 times WT  determines the inside diameter (ID) of a pipe, which determines the liquid capacity of the pipe.


A stainless steel tube is a round/rectangular/squared/oval hollow section that used in applications such as medical devices that require a precise outside diameter. It is measured by the outside diameter (OD) and wall thickness (WT), expressed in inches or millimeters.

The outside diameter is important since it will indicate how much it can hold as a stability factor. 





Stainless steel pipe is generally used to measure its hardness by Brinell, Rockwell, and Vickers hardness indicators.


Brinell hardness

In stainless steel pipe standards, Brinell hardness is the most widely used, often with indentation diameter to indicate the hardness of the material, both intuitive and convenient. But for harder or thinner steel pipes/tubes of steel do not apply.


Rockwell hardness

Stainless steel pipe Rockwell hardness test is the same as Brinell hardness test, are indentation test method. The difference is that it measures the depth of the indentation.

Rockwell hardness test is a widely used method, in which HRC in the steel pipe standards used next to Brinell hardness HB. Rockwell hardness can be applied to determine the metal material from very soft to very hard, it makes up for the Brinell method is not, easier than the Brinell method, can be read directly from the dial of the hardness machine hardness value. However, due to its small indentation, the hardness value is not as accurate as the Brinell method.


Vickers hardness

Stainless steel pipe Vickers hardness test is also an indentation test method that can be used to determine the hardness of very thin metal materials and surface layers. It has the main advantages of Brinell, Rockwell method while overcoming their basic shortcomings, but not as easy as Rockwell method, Vickers method is rarely used in the steel pipe/tube standards.


Hardness testing


Stainless steel pipe inside diameter of 6.0mm or more, the wall thickness of 13mm below the annealed stainless steel pipe/tube, you can use W-B75 type Wechsler hardness tester, it is very fast and easy to test, suitable for stainless steel pipe/tube to do a rapid non-destructive qualified inspection. Stainless steel pipe inner diameter greater than 30mm, wall thickness greater than 1.2mm stainless steel pipe, using Rockwell hardness tester, test HRB, HRC hardness. Stainless steel pipe inner diameter greater than 30mm, wall thickness less than 1.2mm stainless steel pipe, using the surface Rockwell hardness tester, test HRT or HRN hardness. The inner diameter of stainless steel pipe less than 0mm, more than 4.8mm stainless steel pipe, the use of pipe special Rockwell hardness tester, test HR15T hardness. When the inner diameter of stainless steel pipe is greater than 26mm, you can also use Rockwell or surface Rockwell hardness tester to test the hardness of the inner wall of the pipe.



Surface resistance less than 1000 megawatts; abrasion protection; stretchable; excellent chemical resistance; good resistance to alkali metals and acids; toughness; flame retardant



There are many types of stainless steel pipes, with different uses, different technical requirements, and different production methods. The current production of steel pipe outside diameter range 0.1-4500mm, wall thickness range 0.01 ~ 250mm. to distinguish their characteristics, usually according to the following method of classification of steel pipe.


Production method

Stainless steel pipe according to the production method is divided into seamless and welded pipe two categories.

The seamless steel pipe can be divided into hot-rolled pipe, cold-rolled pipe, cold-drawn pipe and extruded pipe, cold-drawn, cold-rolled is the secondary processing of steel pipe; welded pipe is divided into straight seam welded pipe and spiral welded pipe, etc.


Section shape

Stainless steel pipe according to the cross-sectional shape can be divided into the round and un-normal pipe. Un-normal pipes are rectangular tubes, diamond-shaped tubes, oval tubes, hexagonal tubes, eight square tubes, and a variety of cross-sectional asymmetric tubes. Un-normal pipes are widely used in various structural parts, tools, and mechanical parts. Compared with round tubes, tubes generally have a larger moment of inertia and cross-sectional modulus, have greater resistance to bending and torsion, can greatly reduce the weight of the structure, saving steel.
Stainless steel tube according to the shape of the longitudinal section can be divided into equal section tube and variable section tube. Variable section tube has a tapered tube, stepped tube, and periodic section tube.


Pipe end shape

Stainless steel pipes according to the end state can be divided into light pipes and threaded pipes (with threaded steel pipes). The threaded pipe can be divided into the ordinary threaded pipe (water, gas, and other low-pressure pipes, using ordinary cylindrical or tapered pipe thread connection) and special threaded pipe (oil, geological drilling pipe, for important threaded pipe, using special threaded connection), for some special pipe, in order to compensate for the impact of the thread on the strength of the pipe end, usually before the threaded pipe end thickening (inside thickening, outside thickening or inside and outside thickening).


Application classification

According to the use can be divided into oil well pipe (casing, oil pipe, and drill pipe, etc.), pipeline pipe, boiler pipe, mechanical structure pipe, hydraulic pillar pipe, gas cylinder pipe, geological pipe, chemical pipe (high-pressure fertilizer pipe, petroleum cracking pipe) and marine pipe, etc.


Material classification

Stainless steel pipe can be divided into Cr series (400 series), Cr-Ni series (300 series), Cr-Mn-Ni (200 series), and precipitation hardening series (600 series) by composition.

200 series ----- Cr-Ni-Mn austenitic stainless steel 300 series - Cr-Ni austenitic stainless steel.

301 ----- has good ductility and is used for forming products. Can also be rapidly hardened by mechanical processing. Good weldability. Wear resistance and fatigue strength are better than 304 stainless steel.

302 ----- has the same corrosion resistance as 304, but is stronger due to its relatively high carbon content.

303 ----- is easier to machine than 304 by adding small amounts of sulfur and phosphorus.

304----- is 18/8 stainless steel. GB grade is 0Cr18Ni9.


309----- has better temperature resistance than 304.

316 ----- is the second most widely used steel grade after 304, mainly used in the food industry, pharmaceutical industry, and surgical equipment, with the addition of molybdenum to give it a special structure that resists corrosion. SS316 is commonly used for nuclear fuel recovery devices. 18/10 grade stainless steel tubes are also usually qualified for this application.

Type 321 ----- similar to 304 except that the addition of titanium reduces the risk of corrosion in the material welds.

400 Series ----- Ferritic and martensitic stainless steels.

408 ----- Good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni.

409-----The cheapest type (British and American), usually used as automotive exhaust, ferritic stainless steel (chromium steel).

410-----Martensitic (high strength chromium steel), good wear resistance, poor corrosion resistance.

416 ----- added sulfur to improve the processing properties of the material.

420-----"Cutting tool grade" martensitic steel, similar to Brinell high chromium steel, the earliest stainless steel. Also used for surgical knives and can be made very bright.

430 ----- Ferritic stainless steel, used for decorative purposes, e.g. for car accessories. Good formability, but less resistance to temperature and corrosion.

440 ----- High strength cutting tool steel, slightly higher carbon content, after appropriate heat treatment, can be obtained after high yield strength, hardness can reach 58HRC, belong to the hardest stainless steel among. The most common application example is "razor blade". There are three common types: 440A, 440B, 440C, and 440F (easy to work with).

500 Series ----- Heat-resistant chromium alloy steel.

600 Series ----- Martensitic precipitation hardening stainless steel tubes.


Application Prospects

Stainless steel pipe is an economic section of steel, It is an important product in the steel industry, can be widely used in industry, There are common 201, 304, 31 three kinds of materials.

Stainless steel pipe itself is metal-saving economic section stainless steel, it is an important part of efficient steel, especially in oil drilling, smelting, chemical, and transportation industries in greater demand.

Stainless steel pipe is safe, reliable, sanitary and environmentally friendly, economical, thin-walled pipes and the development of new reliable, simple and convenient connection methods successfully, so that it has more irreplaceable advantages of other pipes, the application of engineering will be more and more, the use of more and more popular, the prospects are good.


Connection methods

Stainless steel pipe connection methods are diverse, common types of pipe fittings are compression, live connection, propulsion, push threaded, socket welding, flange connection of the live-joint type, the welding type, and the combination of welding and traditional connection of the derivative series of connection methods.

The scope of application of these connections varies according to their principles, but most of them are easy to install, solid, and reliable. Most of the sealing ring or gasket materials used for the connection are silicon rubber, nitrile rubber, and EPDM rubber, which meet the requirements of national standards and eliminate the worries of users.


Marking Method


Indication method

① Use the international chemical element symbols and the symbols of the country to indicate the chemical composition, using Arabic letters to indicate the content of the composition.
Such as China, Russia 12CrNi3A

② with a fixed number of digits to indicate the steel series or numbers; such as the United States, Japan, 300 series, 400 series, 200 series.

③ with Latin letters and order to form a serial number, only to indicate the use.

Labeling method

American Iron and Steel Institute is a three-digit number to indicate the various standard grades of malleable stainless steel. Among them.

① austenitic stainless steel with 200 and 300 series of numbers marked, for example, some of the more common austenitic stainless steel is marked with 201, 304, 316, and 310.

② Ferritic and martensitic stainless steels are indicated by numbers in the 400 series. Ferritic stainless steel is marked by 430 and 446, martensitic stainless steel is marked by 410, 420 as well as 440C, duplex (austenitic-ferritic).

③ Stainless steels, precipitation-hardening stainless steels, and high-alloys containing less than 50% iron are usually named using patented names or trademarks.


Standard classification

4-1 classification
① national standard  ② industry-standard  ③ local standard ④ enterprise standard Q/C

4-2 Classification.
①Product standards ②Packaging standards ③Method standards ④Basic standards


Weight calculation


W = π(314)× outer diamemter(m)×wall thickness(m) × Pm(density of pipe mertail kg/m3 )×1000= KG/M (weight per meter).

Application requirements

Automotive industry

The main use of stainless steel is the exhaust system, accounting for more than 1/2 of the total amount of automotive stainless steel, 80% of the ferritic stainless steel. The exhaust gas produced by the car engine flows through the exhaust gas intake pipe, front pipe, hose, converter, center pipe, and finally from the muffler. Commonly used steel grades for exhaust systems are 409L, 436L, etc.

Automotive mufflers mainly use stainless steel welded pipes. It is estimated that the stainless steel pipe used in automobiles accounts for about 1.5% of the entire downstream usage of stainless steel pipe, while the use ratio of seamless stainless steel pipe and welded pipe is about 2:1.


Petrochemical industry, including the fertilizer industry

The demand for stainless steel pipe is great, the industry mainly uses stainless steel seamless pipe, specifications include: 304, 321, 316, 316L, 347, 317L, etc., the outer diameter in Φ18-Φ610 or so, the wall thickness in 6mm-50mm or so (generally is the choice of specifications in Φ159mm or more low and medium pressure transmission pipe), the specific application areas are: furnace tube, material transfer tube, heat exchanger tube, etc. Heat exchanger tube, etc.


Water and gas and other fluid transportation

Stainless steel pipeline and its water transmission equipment is the most advanced basic water purification material in the world today, with strong anti-corrosion performance, cast iron pipes, carbon steel pipes, plastic pipes, etc., can not be compared with it.
Water preparation, storage, transmission, purification, regeneration, desalination, and other water industry's best choice of materials.

Stainless steel pipe price $500-10000/ton