Stainless Steel Pipe Fittings

Types, classification, quotation and characteristics of commonly used stainless steel pipes

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Stainless steel pipe is a kind of hollow long steel. which is used as a pipeline for conveying fluids. such as oil. natural gas. water. gas. steam. etc. In addition. when the bending and torsional strength are the same. the weight is light. so Widely used in the manufacture of mechanical parts and engineering structures. Also used to produce a variety of conventional weapons. barrels. shells and so on. Because many pipes are exposed to the outdoors for a long time or buried in the ground. they are easily corroded and rusted and corroded. Therefore. the choice of stainless steel pipe is a good way to avoid these drawbacks and improve the service life of stainless steel pipe.

Common stainless steel pipe model

  1. 304 stainless steel pipe full name SUS304 stainless steel pipe;
  2. SUS304 stainless steel tube is a stainless steel tube of the US grade material. the domestic grade is equivalent to 0Cr19Ni9 stainless steel tube. usually replaced by 0Cr18Ni9;
  3. 201 series – chromium-nickel-manganese austenitic stainless steel;
  4. 300 series – chromium-nickel austenitic stainless steel;
  5. 301 – good ductility. used for molding products. it can also be quickly hardened by mechanical processing. good weldability. abrasion resistance and fatigue strength better than 304 stainless steel;
  6. 302 – corrosion resistance is the same as 304. because the carbon content is relatively high and the strength is better;
  7. 303—by adding a small amount of sulfur and phosphorus to make it easier to cut than 304;
  8. 304 – general model; that is 18/8 stainless steel. GB grade is 0Cr18Ni9;
  9. 309 – better temperature resistance than 304;
  10. 316—After 304. the second most widely used steel grade. mainly used in the food industry and surgical equipment. adding molybdenum to obtain a special structure resistant to corrosion; since it has more than 304 Good resistance to chloride corrosion is therefore also used as “ship steel”; SS316 is usually used in nuclear fuel recovery units; 18/10 grade stainless steels are usually also suitable for this application level;
  11. Model 321 – except for the addition of titanium to reduce the risk of corrosion of the material welds. other performance similar to 304;
  12. 400 series – ferritic and martensitic stainless steel;
  13. 408 – good heat resistance. weak corrosion resistance. 11% Cr. 8% Ni;
  14. 409 – the cheapest model (British and American). usually used as a car exhaust pipe. is a ferritic stainless steel (chrome steel);
  15. 410—Martensite (high-strength chrome steel). good wear resistance and poor corrosion resistance;
  16. 416—The addition of sulfur improves the processing properties of the material;
  17. 420—“cutting grade” martensitic steel. similar to Brinell high-chromium steel. the earliest stainless steel. also used for surgical knives. can be very bright;
  18. 430—ferritic stainless steel. used for decoration. for example. for automotive accessories. good formability. but poor temperature resistance and corrosion resistance;
  19. 440—high-strength cutting tool steel with slightly higher carbon content. After proper heat treatment. it can obtain higher yield strength and hardness can reach 58HRC. It belongs to the hardest stainless steel. The most common application example is “shaving blade”. “. there are three commonly used models: 440A. 440B. 440C. in addition to 440F (easy processing type);
  20. 500 series – heat-resistant chrome alloy steel;
  21. 600 series – martensitic precipitation hardening stainless steel;
  22. 630 – the most commonly used type of precipitation hardened stainless steel. usually also called 17-4; 17% Cr. 4% Ni.

Classification of stainless steel pipes

1. Classification by production mode

Stainless steel pipes are divided into two types according to production methods: seamless pipes and welded pipes. Seamless steel pipes can be divided into hot rolled pipes. cold rolled pipes. cold drawn pipes and extruded pipes. Cold drawing and cold rolling are secondary to steel pipes. Processing; welded pipes are divided into straight welded pipes and spiral welded pipes.

2. According to the shape of the section

Stainless steel tubes can be divided into round tubes and shaped tubes according to the cross-sectional shape. The special-shaped tube has a rectangular tube. a rhombic tube. an elliptical tube. a hexagonal tube. an eight-sided tube. and various cross-section asymmetric tubes. Shaped tubes are widely used in a variety of structural parts. tools and mechanical parts. Compared with the round pipe. the special-shaped pipe generally has a large moment of inertia and a section modulus. and has a large bending and torsion resistance. which can greatly reduce the structural weight and save steel. Stainless steel pipes can be divided into equal-section pipes and variable-section pipes according to the longitudinal section shape. The variable section pipe has a conical pipe. a stepped pipe and a periodic section pipe.

3. By material classification

Stainless steel pipes are divided into ordinary carbon steel pipes. high-quality carbon structural steel pipes. alloy structural pipes. alloy steel pipes. bearing steel pipes. stainless steel pipes. and bimetallic composite pipes. coatings and coated pipes for saving precious metals and meeting special requirements. .

4. According to the shape of the tube end

The stainless steel tube can be divided into a light pipe and a wire tube (threaded steel pipe) according to the state of the pipe end. The wire tube can be divided into ordinary car wire tube (transfer water. gas and other low pressure pipes. using ordinary cylindrical or conical pipe thread connection) and special threaded pipe (oil. geological drilling pipe. for important wire pipe. use Special thread connection). for some special tubes. in order to compensate for the influence of the thread on the strength of the tube end. the tube end is usually thickened (inner thickening. outer thickening or inner and outer thickening) before the wire.

5. Classification by purpose

According to the application. it can be divided into oil well pipe (casing. oil pipe and drill pipe. etc.). pipeline pipe. boiler pipe. mechanical structural pipe. hydraulic pillar pipe. gas cylinder pipe. geological pipe. chemical pipe (high pressure fertilizer pipe. petroleum cracking pipe). ) and ships and other pipes.

6. Classification by production method

  1. Seamless pipe – hot rolled pipe. cold rolled pipe. cold drawn pipe. extruded pipe. top pipe;
  2. Welded pipe

  • According to the process points – arc welded pipe. electric resistance welded pipe (high frequency. low frequency). gas welded pipe. furnace welded pipe;
  • According to the weld seam – straight seam welded pipe. spiral welded pipe;

7. Classification by section shape

  1. Simple section steel pipe – round steel pipe. square steel pipe. elliptical steel pipe. triangular steel pipe. hexagonal steel pipe. diamond steel pipe. octagonal steel pipe. semicircular steel circle. others;
  2. Complex section steel pipe – unequal hexagonal steel pipe. five-petal plum-shaped steel pipe. double convex steel pipe. double concave steel pipe. melon-shaped steel pipe. conical steel pipe. corrugated steel pipe. case steel pipe. and others.

8. According to wall thickness classification

Thin-walled steel pipes and thick-walled steel pipes.

(1) Welded pipe classification

1. Classified by purpose

It is also divided into general welded pipe. galvanized welded pipe. blown oxygen welded pipe. wire casing. metric welded pipe. idler pipe. deep well pump pipe. automobile pipe. transformer pipe. electric welding thin wall pipe. electric welding shaped pipe and spiral welded pipe.

  1. General welded pipe: The general welded pipe is used to transport low pressure fluid. Made of Q195A. Q215A. Q235A steel. It can also be made of other mild steel that is easy to weld. The steel pipe is subjected to experiments such as water pressure. bending and flattening. and has certain requirements on the surface quality. Usually. the delivery length is 4-10 m. and the fixed length (or double rule) is often required for delivery. The specification of the welded pipe is expressed by the nominal diameter (mm or inch). The nominal diameter of the welded pipe is different from the actual one. The welded pipe has two kinds of ordinary steel pipe and thick steel pipe according to the specified wall thickness. The steel pipe is divided into two types according to the pipe end form with and without thread.
  2. Galvanized steel pipe: In order to improve the corrosion resistance of the steel pipe. the general steel pipe (black pipe) is galvanized. Galvanized steel pipes are divided into hot-dip galvanizing and electric steel zinc. The hot-dip galvanizing galvanized layer is thick and the cost of electro-galvanizing is low.
  3. Blown oxygen welded pipe: used as a steel pipe for oxygen blowing. generally with small diameter welded steel pipe. the specifications are from 8/8 inch to 2 inch. Made of 08. 10. 15. 20 or Q195-Q235 steel strip. For corrosion protection. some are aluminized.
  4. Wire casing: that is. ordinary carbon steel electric welded steel pipe. used in concrete and various structural power distribution projects. commonly used nominal diameter from 13-76mm. The sleeve of the wire sleeve is thin. and most of it is coated or galvanized. and a cold bend test is required.
  5. Metric welded pipe: Specification for seamless pipe form. welded steel pipe with outer diameter * wall thickness mm. tropical or cold band welding with ordinary carbon steel. high quality carbon steel or ordinary low alloy steel. or tropical After welding. it is made by cold dialing method. Metric welded pipes are divided into general and thin walls. which are commonly used as structural members. such as transmission shafts. or for conveying fluids. Thin walls are used to produce furniture. lamps. etc.. to ensure the strength and bending test of steel pipes.
  6. Roller tube: used for belt conveyor roller welded steel pipe. generally made of Q215. Q235A. B steel and 20 steel. diameter 63.5-219.0mm. The pipe bending degree. the end surface should be perpendicular to the center line. and the ellipticity is required. Generally. the water pressure and the flattening test are performed.
  7. Transformer tube: used to manufacture transformer heat pipe and other heat exchangers. It is made of ordinary carbon steel and requires flattening. flare. bending and hydraulic test. Steel pipes are delivered in fixed lengths or multiples. which have certain requirements for the bending of steel pipes.
  8. Shaped tube: square tube. rectangular tube. hat tube. empty steel door and window steel tube welded by ordinary carbon knot structural steel and 16Mn steel. mainly used as agricultural machinery components. steel window doors. etc.
  9. Electric welding thin wall tube: mainly used for making furniture. toys. lamps and so on. In recent years. thin-walled tubes made of stainless steel strips have been widely used. such as high-grade furniture. decoration. and fences.
  10. Spiral welded pipe: It is made by rolling a low carbon carbon structural steel or a low alloy structural steel strip into a tube blank at a certain angle of a helix (called a forming angle). and then welding the pipe joint to make it narrower. The strip produces large diameter steel tubes. Spiral welded pipe is mainly used for oil and natural gas transmission pipelines. and its specifications are expressed by outer diameter * wall thickness. Spiral welded pipes are single-sided welded and double-sided welded. The welded pipe shall ensure that the hydraulic test and the tensile strength and cold bending performance of the weld are in compliance with the regulations.

(2) Classification of spiral tubes

Spiral submerged arc welded pipe for pressure fluid transportation is mainly used for conveying oil and natural gas pipelines. The steel pipe has strong pressure bearing capacity and good plasticity. which is convenient for welding and processing. Generally. spiral submerged arc welded steel pipe for low pressure fluid transportation adopts double-sided automatic Submerged arc welded steel pipe for general low-pressure fluid transportation such as water. gas. air and steam made by submerged arc welding or single-sided welding.

(3) Classification of bearing steel

At present. there are five main types of bearing steels used in countries around the world. namely high carbon chromium bearing steel. carburized bearing steel. stainless bearing steel. high temperature bearing steel. and medium carbon bearing steel.

Stainless steel pipe quote

  1. At present. there are mainly stainless steel pipes of 304. 201. and 301 materials on the market. Different materials have different performances. The difference between different materials is mainly reflected in the amount of nickel and chromium. The 304 stainless steel tube contains 18 chrome and 8-9 nickel. The other two materials. 201 and 301. have a chromium and nickel content of 14. 16 and 1. respectively. The higher the nickel and chromium content. the better the performance.
  2. 316 stainless steel plate surface is smooth. with high plasticity. toughness and mechanical strength. acid. alkaline gas. solution and other media corrosion. It is an alloy steel that does not rust easily. but it does not rust. The corrosion resistance of stainless steel mainly depends on its alloy composition (chromium. nickel. titanium. silicon. aluminum. etc.) and the internal structure. and the main role is chromium. Chromium has high chemical stability and can form a passivation film on the steel surface to isolate the metal from the outside. protect the steel plate from oxidation. and increase the corrosion resistance of the steel plate. After the passivation film is destroyed. the corrosion resistance is lowered. The price is 100-120 yuan.
  3. 200 stainless steel pipe price quotes. also need to look at the specifications and wall thickness. So not the same requirements. not the same price quote. Wenzhou Rongrui stainless steel price is reasonable.
  4. In terms of price. stainless steel pipes are generally determined by weight. In the market. they are generally more than ten yuan a kilogram. However. for some industrial purposes. large quantities of pipes are required. usually in tons. unit of measurement.

Stainless steel tube characteristics
1. Corrosion resistance

Most stainless steel products require good corrosion resistance. Some foreign merchants also carry out corrosion resistance test on products: use NACL aqueous solution to warm to boiling. after a period of time. pour off the solution. wash and dry. weigh the weight loss. to determine the Degree of corrosion (Note: When the product is polished. the composition of Fe in the abrasive cloth or sandpaper will cause rust on the surface during the test).

2. Weldability

The requirements for welding performance vary from product to product. A type of tableware generally does not require welding performance. and even includes some pot enterprises. However. most products require good welding performance of raw materials. such as second-class tableware. thermos cups. steel pipes. water heaters. water dispensers. etc.

3. Polishing performance

At present. stainless steel products are generally polished during the production process. and only a few products such as water heaters. water dispenser liners. etc. do not need to be polished. Therefore. this requires a good polishing performance of the raw material.

Quality control method for stainless steel pipe construction

  1. Stainless steel pipes must be cleaned before installation.
  2. When the pipeline is long or the temperature of the conveying medium is high. the compensator should be set at the appropriate position. The compensator usually has a square shape and a waveform. When selecting. it should be selected according to the working pressure and temperature.
  3. The stainless steel pipe is not allowed to be in contact with the carbon steel bracket. A stainless steel piece or a plastic or rubber gasket containing no chloride ions should be placed between the bracket and the pipe.
  4. When using the pressure connection. it should be connected by special pipe fittings. and the insulation between the pipe fittings and the stainless steel pipe can be made of plastic. rubber or asbestos rubber plates without chloride ions.
  5. When the stainless steel pipe passes through the wall or the floor. the casing should be installed. The gap between the casing and the stainless steel pipe should not be less than 10mm. and the insulation should be filled in the gap. The asbestos rope can be used. and the iron and rust should not be used. Miscellaneous stuffing.
  6. The quality of the sub-projects shall meet the following requirements:

The inspection batch included in the 1 sub-project shall meet the requirements for qualified quality.
In general. 201 stainless steel welded pipe is resistant to high temperature 315 degrees. and the ultimate temperature of 304 stainless steel welded pipe is 650 degrees. When the temperature exceeds this temperature. the heavy metal will precipitate. When the stainless steel welded pipe is heated more than this degree. the stainless steel pipe creep material will start to deform. . Therefore. the environment in which the stainless steel pipe is used should be below the corresponding temperature. If the temperature exceeds this temperature. the stainless steel pipe will definitely be broken. Due to the increase in nickel content. the high temperature resistance of the stainless steel tube can be improved. so the 304 stainless steel tube has a slightly higher temperature resistance than the 201 stainless steel tube.
Source: China Stainless Steel Pipes Manufacturer – Yaang Pipe Industry Co.. Limited (www.yaang.com)

Article Categories:
Steel Pipe

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