What are stainless steel pipes
What are stainless steel pipes?
Table of Contents
- What are stainless steel pipes?
- What is the chemical composition of stainless steel pipe?
- The influence of chemical elements in the stainless steel pipe material
- What is the application of stainless steel pipe?
- The Advantages Of Stainless Steel Pipes
- Standards of steel pipes
- The Surface Of Stainless Steel Tubing
- The production process of stainless steel pipe
- Dimensional tolerance of ERW steel pipe
- Ends of stainless steel pipe
- Length of stainless steel pipe
- Inspection Quality of stainless steel pipe
- Acceptance of steel pipes
- Tolerance standard of steel pipe
- Packing of stainless steel pipe
- Delivery of stainless steel pipe
- How to choose stainless steel pipes?
Stainless steel pipe is a kind of hollow cylindrical steel pipe, which can be used as a fluid transmission pipeline system, mainly widely used in petroleum, chemical, medical, food, light industry, mechanical instruments and other industrial transport pipelines and mechanical structural components, etc.. Stainless steel pipe is made of billets of acid and heat resistant grades, heated, perforated, sized, hot rolled and cut.
What is the chemical composition of stainless steel pipe?
Stainless steel is a corrosion-resistant alloy of iron, chromium and, in some cases, nickel and other metal metals.
Completely and infinitely recyclable, stainless steel is a “green metal material” in the best sense of the word. In fact, within the construction industry, its actual recycling rate is close to 100%. Stainless steel is also environmentally neutral and inert, and its longevity ensures that it meets the needs of sustainable construction. In addition, when in contact with elements such as water, it does not leach compounds that could alter its composition.
In addition to these environmental benefits, stainless steel is aesthetically pleasing, extremely hygienic, easy to maintain, highly durable, and has a wide range of uses. As a result, stainless steel can be found in many everyday items. It also plays an important role in a range of industries, including energy, transportation, construction, research, medicine, food and logistics.
Composition of stainless steel pipes
The influence of chemical elements in the stainless steel pipe material
Steel is an alloy of iron and carbon. Stainless steel is steel that contains at least 10.5% chromium and less than 1.2% carbon and other alloying elements. The corrosion resistance and mechanical properties of stainless steel can be further improved by adding other elements such as nickel, molybdenum, titanium, niobium, manganese, etc.
When in contact with oxygen, a chromium oxide layer forms on the surface of the material. This passive layer protects it and has a unique ability to repair itself.
The functions and elements of various parts of steel are introduced.
- 1. Carbon, silicon, manganese, sulfur, phosphorus is the main impurity elements in pig iron and carbon steel, commonly known as the “five elements”. Because they have a great impact on the performance of steel, the general analysis needs to determine them.
- 2. Chromium (Cr): In structural steel and chromium, chromium can significantly improve the strength, hardness and wear resistance, but at the same time reduce plasticity and toughness. Chromium can improve the oxidation resistance and corrosion resistance of steel, so it is an important alloying element for stainless steel and heat-resistant steel.
- 3. Nickel (Ni): Nickel can improve the strength of steel, while maintaining good ductility and toughness. Nickel has high corrosion resistance to acids and bases, rust resistance and heat resistance at high temperatures. However, because nickel is a scarce resource, other alloying elements should be used instead of nickel-chromium steel.
- 4. Molybdenum (Mo): molybdenum can refine the grain of steel, improve hardenability and thermal strength, and maintain sufficient strength and creep resistance at high temperatures (long-term stress at high temperatures, deformation occurs, called creep). The addition of molybdenum to structural steel improves mechanical properties. It can also inhibit the brittleness of alloy steels due to fire. The red color of tool steels can be improved.
- 5. Titanium (Ti): Titanium is a strong deoxidizer in steel. It can make the internal organization of steel dense and refine the grain force; reduce aging sensitivity and cold brittleness. Improve the welding performance. In the chromium 18 nickel 9 austenitic stainless steel to add the appropriate titanium can avoid intergranular corrosion.
- 6. Vanadium (V): Vanadium is an excellent steel deoxidizer. Adding 0.5% vanadium to steel can refine the grain structure and improve strength and toughness. Vanadium and carbon form carbides to improve the high temperature and pressure of hydrogen corrosion resistance.
- 7. Tungsten (W): Tungsten has a high melting point and a high specific gravity. It is a precious metal element. Tungsten and carbon form tungsten carbide, which has high hardness and wear resistance. Adding tungsten to the tool steel can significantly improve the red hardness and thermal strength of tools and forging dies.
- 8. Niobium (Nb): niobium can refine the grain, reduce the steel superheat sensitivity and tempering brittleness, improve strength, but plasticity and toughness is reduced. Adding bismuth in ordinary low-alloy steel can improve its resistance to atmospheric corrosion and high temperature hydrogen, nitrogen and ammonia corrosion. Niobium can improve welding properties. Twisting of austenitic stainless steel can prevent intergranular corrosion.
- 9. Cobalt (Co): Cobalt is rare and valuable for special steels and alloys, such as hot strength steels and magnetic materials.
- 10. Copper (Cu): Copper can improve the strength and toughness, especially atmospheric corrosion. The disadvantage is that it is prone to thermal embrittlement during hot work, and the copper content is significantly reduced by more than 0.5%. When the copper content is less than 0.50%, there is no effect on weldability.
- 11. Aluminum (Al): Aluminum is a common deoxidizer in steel. Small amounts of aluminum are added to steel to refine grain size and improve impact toughness, such as 08Al steel for deep-drawn thin plates. Aluminum also provides oxidation resistance and corrosion resistance. Aluminum combines with chromium and silicon to significantly improve the steel’s resistance to high temperatures and corrosion. The disadvantage of aluminum is that it affects the hot workability, weldability and machinability of steel.
- 12. Boron (B): add trace amounts of boron to the steel can improve the denseness and hot rolling properties of steel, and improve the strength.
- Nitrogen (N): Nitrogen can improve the strength, low-temperature toughness and weldability of steel, and improve the aging sensitivity.
What is the application of stainless steel pipe?
In the chemical industry, stainless steel tube is used as a device such as an instrumentation manifold and pipe network. In nuclear power plants and pharmaceutical factories, stainless steel tubular heat exchangers are used for condensers and evaporators.
Stainless steel tube is widely used in mechanical processing, petrochemical industries, food and medical industries, water conservancy, construction, mining and other industries.
- Stainless steel tubes are not only used for high temperature resistance and corrosion resistance but also for high strength and low weight. Stainless steel tubes have been used in hydraulic power steering systems as a hydraulic fluid pump.
- In the chemical industry, stainless steel tube is used as a device such as an instrumentation manifold and pipe network. Stainless steel tubing is widely used in production processes such as distillation columns and scrubbers.
- Stainless steel tubes are common in the petroleum industry and petrochemical industries. Stainless steel tubes are used to store and transport natural gas, chemicals, food, water, air, liquid gas or other fluids.
- In nuclear power plants and pharmaceutical factories, stainless steel tubular heat exchangers are used for condensers and evaporators.
- Food machinery industry: tunnel-type microwave drying sterilization equipment, tube-type microwave heating equipment barbecue machine production line.
- Water Industry : sewage treatment systems, seawater desalination system pipeline networks; ultrafiltration pipe network system; filter housing ; reverse osmosis device ; seawater desalination system reverse osmosis device; marine oil field platform jacket , ocean engineering.
Stainless steel tubes can be manufactured into all kinds of shapes according to customer requirements. Such as round shape, flat shape and so on. For example: stainless steel tube/pipe with a diameter of 2mm-250mm or more; flange connection with weld seam; butt welded seam at both ends; flare connection or socket welded seam at one end etc..
The Advantages Of Stainless Steel Pipes
There are many advantages of using stainless steel pipe in the construction industry. Some of those advantages are listed below:
The stainless steel pipe system helps decrease maintenance costs.
Stainless steel pipes are easy to clean and maintain. They are not affected by corrosion or rust, which means that you can save money by not having to replace them as often as other types of pipes would require.
The stainless steel pipe system helps decrease maintenance costs because the system itself is designed for durability and longevity. The materials used in this type of system do not corrode or rust over time, so there is no need for extensive repair work on the actual product itself.
The corrosion resistance of the stainless steel pipe system is good.
Stainless steel pipe is resistant to corrosion. It does not rust, oxidize or corrode, and can be used in any environment. In addition, stainless steel pipe is not affected by water, acids or alkali substances such as sodium hydroxide (NaOH), sulfuric acid (H2SO4), hydrochloric acid (HCl), nitric acid (HNO3), sodium hypochlorite solution (NaOCl) and so on.
Stainless steel pipe is tough and durable.
The toughness of stainless steel pipes makes them resistant to corrosion, wear and tear. They are also resistant to damage from chemicals and heat.
The ductility of stainless steel pipes allows them to be fabricated into various sizes and shapes for different projects.
When one thinks of ductility, they imagine a metal wire being stretched out or bent around an object. However, the same principle applies with the ductility of stainless steel pipes. A stainless steel pipe can be formed or bent into many different forms and sizes depending on your project’s needs. Since there are no limitations on how much force you put on your pipe during fabrication, you can achieve almost any shape imaginable for any use case you have in mind!
Stainless steel pipes have many advantages other metals do not.
Stainless steel is a metal alloy that is created by mixing chromium and iron. The resulting material has many properties that make it ideal for pipes. It is strong, durable, corrosion resistant, flexible and easy to install.
Stainless steel pipes are made from a mixture of chromium and iron which makes them very strong and durable. They are not easily corroded by liquids or other elements found in soil or water systems because they have been treated with an anti-corrosion coating which protects against damage caused by exposure to air or water over time.
Stainless steel pipes offer many benefits over their metal counterparts. They are durable, corrosion resistant, and easy to work with in construction projects. The ductility of stainless steel pipes allows them to be fabricated into various sizes and shapes for different projects. It also helps decrease maintenance costs because they don’t need much care or attention from their owners when it comes time for cleaning or repairs.
Standards of steel pipes
Steel pipes by standards include ASTM, JIS, DIN, Customers for international, etc…
We can produce and sell cold drawn and hot rolled steel pipes as well as cold drawn special section steel pipes, which are widely used in petrochemical, boiler, automobile, machinery, construction, and other industries.
API SPEC 5L/ 5CT
Specification for Casing and Tubing, Eighth Edition, Petroleum and natural gas industries-Steel pipes for use as casing or tubing for wells.
|Product name||Executive standard||Dimension (mm)||Steel code/ Steel grade|
|Casting||API 5CT||114-219 x 5.2-22.2||J55, K55, N80, L80, P110|
|Tubing||API 5CT||48.3-114.3 x 3.2-16||J55, K55, N80, L80, H40|
|Casting||API 5L||10.3-1200 x1.0-120||A, B, X42, X46, X52, PSL1 / PSL2|
ASTM / ASME
American Society for Testing and Materials(ASTM), American Society of Mechanical Engineers (ASME)
|Product name||Executive standard||Dimension (mm)||Steel code/ Steel grade|
|Black and Hot-dipped Zinc-coated Steel Pipes Seamless||ASTM A53||0.3-1200 x 1.0-150||GR.A, GR.B, GR.C|
|Seamless Carbon Steel for High-Temperature Service||ASTM A106||10.3-1200 x 1.0-150||GR.B, GR.C|
|Seamless Cold-drawn Low-Carbon Steel Heat-Exchanger and Condenser Tubes||ASTM A179||10.3-426 x 1.0-36||Low Carbon Steel|
|Seamless Carbon Steel Boiler Tubes for High Pressure||ASTM A192||10.3-426 x 1.0-36||Low Carbon Steel|
|Seamless Cold-drawn Intermediate Alloy Steel Heat-exchanger and Condenser Tubes||ASTM A199||10.3-426 x 1.0-36||T5, T22|
|Seamless Medium-carbon Steel Boiler and Superheater Tubes||ASTM A210||10.3-426 x 1.0-36||A1, C|
|Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-exchanger Tubes||ASTM A213||10.3-426 x 1.0-36||T5, T9, T11, T12, T22, T91|
|Seamless Carbon and Alloy Steel for Mechanical Tubing||ASTM A333||1/4″-42″ x SCH20-XXS||Gr1, Gr3, Gr6|
|Seamless ferritic alloy-steel pipe for high-temperature service||ASTM 335/335M||1/4″-42″ x SCH20-XXS||P5, P9,P11, P91, P22, P92|
|Seamless Cold-drawn Carbon Steel Feedwater Heater Tubes||ASTM A556||10.3-426 x 1.0-36||A2, B2|
DIN/EN – European Standards for steel
Germany Safety(GS), Deutsches Institut für Normung(DIN)
|Product name||Executive standard||Dimension (mm)||Steel code/ Steel grade|
|Seamless Steel Tubes for Elevated Temperature||DIN 17175||10-762 x 1.0-120||St35.8,St45.8, 10CrMo910, 15Mo3, 13CrMo44, STPL340, STB410, STB510, WB36|
|Manufacturing pipeline, vessel,equipment, and pipe fittings.||DIN 1629||13.5-762 x 1.8-120||St37.0, St44.0, St52.0|
|Seamless steel tubes for pressure purposes||EN 10216||
4.0-60.0 x 0.5-8
5-7 m manufacturing length
|P235GH TC1, P235GH TC2, 16Mo3|
|Seamless precision steel tube applications||EN 10305-1||13.5-165.1 x 1.8-4.85||St33.2|
|Seamless Precision Steel Tube||DIN 2391||4.0-60.0 x 0.5-8||St35, St45, St52|
|Seamless Steel Tubes||DIN 2440||13.5-165.1 x 1.8-4.85||St33.2|
Japanese Industrial Standards (JIS) specify the standards used for industrial activities in Japan.
|Product name||Executive standard||Dimension (mm)||Steel code/ Steel grade|
|High pressure and high-temperature service||JIS G3454/5/6||19.05-114.3 x 2.0-14||JIS G3454(STPG370, STPG410), JIS G3455(STS370, STS410, STS480), JIS G3456(STPT370, STPT410, STPT480)|
|Tubes are used for machinery, automobiles, bicycles, furniture, appliances, and other machine parts.||JIS G3445||19.05-114.3 x 2.0-14||STKM11A, STKM12(A,B,C), STKM13(A,B,C), STKM14(A,B,C).|
|Carbon steel/Alloy steel boiler and heat exchanger tubes||JIS G3461,2||19.05-114.3 x 2.0-14||
G3461(STB340, STB410, STB510)
|Seamless steel tubes for high-pressure gas cylinder||JIS G3429||
19.05-114.3 x 2.0-14
Length: max 16000mm
|STH11, STH12, STH21, STH22|
|Product name||Executive standard||Dimension (mm)||Steel code/ Steel grade|
|Low and medium pressure boiler seamless pipe||GB 3087||19.05-114.3 x 2.0-14||10#, 20#|
|Low-temperature heat exchanger tubes seamless steel pipe||GB/T18984||19.05-351 x 2.0-14||06Ni3MoDG, 09DG, 09Mn2VDG, 10MnDG, 16MnDG|
|High pressure and above pressure steam boiler tubes with a high-quality carbon structure.||GB5310||19.05-114.3 x 2.0-14||20G, 20MnG, 25MnG, 15MoG, 20MoG, 12CrMoG, 15CrMoG(T12/P12), 12CrMoG, 12Cr2MoWVTiB.|
The Surface Of Stainless Steel Tubing
Pickled surface stainless steel pipe (polished)
The surface of stainless steel pipe is pickled. The pipe is pickled and passivated after solid solution annealing, and then a passivated coating is obtained to improve corrosion resistance. If there are no special requirements for the surface, the tube will undergo a grinding process.
Polishing stainless steel pipes
Polishing here is mechanical polishing and includes both inner and outer surfaces. The roughness can be at least 0.4µm (16µin) or 300 grit produced by polishing. Mechanical polishing uses fully automated polishing machines to control surface accuracy and roughness for food grade and bioengineering needs.
Bright Annealed/Barium Tubes
BA tubes are bright annealed stainless steel tubes, which is a different heat treatment process from ordinary stainless steel solution annealing to obtain better accuracy and surface roughness. BA tubes do not need to be pickled again and their roughness can meet the polishing accuracy requirements, but the cost is higher than mechanically polished stainless steel tubes.
Electrolytic polishing/EP tube
Stainless steel EP tubes are high purity, high precision tubes used in demanding environments such as bioengineering, semiconductors, laboratories and precision instruments. The inner surface roughness of our EP tubes can reach 0.2 to meet the stringent requirements of various working conditions.
The production process of stainless steel pipe
According to the manufacturing process of seamless stainless steel pipe, seamless stainless steel pipe can be divided into hot-rolled seamless stainless steel pipe and cold-drawn seamless stainless steel pipe.
Process flow chart of cold-drawn seamless stainless steel pipe
Cold-drawn seamless stainless steel pipe process.
Round tube billet → heating → perforation → head → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → blank tube → heat treatment → straightening → Hydraulic test (inspection) → mark → storage.
In a General cold-rolled strip machine, the volume should be continuously annealed (CAPL unit) to eliminate cold quenching and rolling stress, or batch annealing to achieve the mechanical properties specified in the corresponding standards. The surface quality, appearance, and dimensional accuracy of cold-rolled steel sheets are better than that of hot-rolled steel sheets, and the thickness of the product is about 0.18mm for rolling thin, so it is favored by the majority of users.
The cold-drawn steel pipe is made of hot-rolled steel coil as raw material, it’s subjected to pickling to remove scale and then cold-rolled. The finished product is rolled hard roll. The cold work hardening is caused by continuous cold deformation to make the strength and hardness of the rolled hard roll rise and tough. The plastic index is reduced, so the stamping performance will deteriorate and can only be used for parts that are simply deformed.
Process flow chart of hot rolled seamless stainless steel pipes
The raw material for rolling seamless tubes is round tubes, and the tube embryos are cut to raw lengths of about 1 meter by a cutting machine and heated by a conveyor belt to the furnace.
Hot-rolled (extruded seamless steel pipe)
Round tube billet → heating → perforation → three-roll cross-rolling, continuous rolling or extrusion → pipe removal → sizing (or reducing diameter) → cooling → blank tube → straightening → water pressure Test (or flaw detection) → mark → into storage.
The billet is fed into a heating furnace at a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. The control of the furnace temperature is crucial to grind the round air ducts and release the pressure after the punch. One of the taper roller punches is generally higher than the ordinary taper roller punch this kind of punch, has high production efficiency, good product quality, large perforation expansion, and wear-resistant various steel. After perforation, the round pipe is cross-rolled, rolled, or extruded by three rollers.
After extruding the pipe size. The sizing machine through the high-speed rotation of the conical drill into the billet punch to form a steel pipe. The inner diameter of the steel pipe is determined by the length of the outer diameter of the sizer bit. After sizing, the steel pipe enters the cooling tower to be cooled by water spray. After the steel pipe is cooled, it needs to be straightened. Sent by the delivery tube through the straightening of the metal flaw detection machine (or hydraulic test) for internal flaw detection. Will detect cracks, bubbles, and other problems inside the steel pipe.
The process flow of a hot rolled seamless stainless steel pipe production base can be summarized in three stages: perforation, extension, and finishing.
The main purpose of the perforation process is to become a solid round billet perforated with a hollow shell. The capillary tube does not meet the requirements of the finished product in terms of specification, precision, and surface quality, and further improvement is required to get the metal through the deformation. The main purpose of the drawing machine is to further reduce the cross-sectional figure (main compression wall) to obtain a greater axial extension, thus improving the dimensional accuracy, surface quality, and organizational properties of the capillary pipe.
Steel pipe quality inspection will also be done by strict hand selection. The quality of steel pipe is monitored and inspected using the number, size, and production lot of spray paint. A cable car hanging in the warehouse.
How to make welded stainless steel pipes & tubes?
Yaang produces a wide range of welded steel pipes, including ERW, HFI, EFW, LSAW, DSAW, and UOE-type stainless steel pipes and their respective flanges and fittings.
Welded steel pipe manufacturing process is simple and efficient, with many varieties, different specifications, less equipment, and less capital, but the total strength is not as good as a seamless steel pipe. since the 1930s, with the rolling production of high-quality strip steel and the rapid development of welding detection technology, the quality of the weld seam continues to improve, and the specifications of welded steel pipe are increasing, replacing non-pipe joints in more and more areas.
Pipes can be divided into two types according to the basic shape of the longitudinal weld seam, and spiral welded pipe.
- (1) LSAW pipe: simple production process, high efficiency, low cost, and rapid development. Longitudinal more general industrial use.
- (2) Spiral welded steel pipe: longitudinal strength is generally higher than this, can be narrower diameter billet production, but also use the same width of the billet production of different diameter welded pipe; but compared with the same length of straight seam pipe, spiral welded steel pipe weld length of 30%-100%, and lower productivity; therefore, smaller diameter pipes actually use straight seam welding, large diameter spiral welded pipe is mostly used.
Pipeline use is divided into the following categories.
- (1) General welded steel pipe: welded steel pipe for the transport of general low-pressure fluids. Contains Q195A, Q215A, and Q235A steel. Can be easily applied to other soft steel welded steel pipe pressure, bending, flattening, and other experiments, here there are certain surface quality requirements, the delivery length is usually 4-10m, often required to cut to a certain length (or double length) delivery s specifications and nominal pipe diameter indicated (mm or inches) the difference between the nominal diameter and the actual diameter of the pipe required thick-walled ordinary steel and steel pipe is two kinds of steel, according to the form of pipe Divided into two types with threaded ends and non-threaded ends.
- (2) Galvanized welded steel pipe: To improve the corrosion resistance of steel pipe, general steel pipe (single reed pipe) for galvanized steel and electrical steel, hot dipped galvanized zinc there are two kinds of galvanized thickness, galvanized low cost.
- (3) Oxygen welded steel pipe: piping for steelmaking oxygen, usually with small diameter welded steel pipe, size from 3/8 inch to 2 inches 8. made of 08, 10, 15, 20 or Q195-Q235 steel strip corrosion, for partial aluminizing treatment.
- (4) Line pipe: welded steel pipe is also common carbon steel, concrete, and various distribution engineering structures used in steel pipe, commonly used nominal diameter of 13-76mm.
- (5) Metric welded steel pipe: seamless form, specifications expressed in millimeters diameter * wall thickness of welded steel pipe, with ordinary carbon steel, high carbon steel or low alloy steel and P welding to tropical and cold regions, or welded with tropical methods to call cold regions. Metric and thin-walled tube points are commonly used in structural parts, such as shafts or transmission fluid, for the production of thin-walled furniture, lamps, etc., to ensure the strength of steel and bending tests.
- (6) Roller: roller conveyor with welded steel pipe, generally 304/304L, 316/316L, 2205, 2507, Q215, Q235A, 45# steel, B steel, and 20# steel, diameter 63.5-219.0mm. bending of the tube, the end is perpendicular to the center line, ellipticity has certain requirements, general test pressure, and flatness.
Dimensional tolerance of ERW steel pipe
Tolerance of outside diameter
|Out Diameter||Tolerance of Pipe End||Tolerance of Pipe Body|
Tolerance of wall thickness
|Grade||Out Diameter||Wall Thickness|
Ends of stainless steel pipe
For the ends of pipes are 3 standard versions available.
- Plain Ends (PE)
- Threaded Ends (TE)
- Beveled Ends (BE)
The BE implementation is applied to all diameters of buttweld flanges or buttweld fittings and will be directly welded (with a small gap of 3-4 mm) to each other or to the pipe.
Ends are mostly beveled to the angle of 30° (+ 5° / -0°) with a root face of 1.6 mm (± 0.8 mm).
Length of stainless steel pipe
Piping lengths from the factory are not exactly cut to length but are normally delivered as:
- The single random length has a length of around 5-7 meter
- The double random length has a length of around 11-13 meter
- Shorter and longer lengths are available, but for calculation, it is wise, to use this standard length;
- other sizes are probably more expensive.
Inspection Quality of stainless steel pipe
Our factory is ISO 9001 and CE-PED approved manufacturer. We believe that quality is the life of the company. To provide quality products is the thing we are doing.
- PMI test to ensure the material quality;
- Dimension controlling during fabricating and finishing;
- 100% Visual and surface examination;
- NDT test (Eddy Current and Hydro Test);
- Another requirement on request.
|Eddy Current Test||Hydrostatic Test||Radiography Test (for welded pipe)||Liquid Dye Penetrant Test|
|Bending Test||Ultrasonic Test||Tensile Test||Flaring Test|
|Flattening Test||Hardness Test||Positive Material Identification (PMI)||Surface Roughness|
|Hardness Test||Dimension Examination||Visual Checking||Impact Test|
|Intergranular Corrosion Test||Grain Size Test||Chemical Analysis||Other tests on the requirement|
Acceptance of steel pipes
The acceptance of the steel pipe is mainly divided into the following contents:
- A. Nominal size: It is the nominal size specified in the standard, which is the ideal size that users and manufacturers hope to get, and also the order size specified in the contract.
- B. Actual size: It is the actual size obtained in the production process, which is often larger or smaller than the nominal size. This phenomenon of larger or smaller than the nominal size is called deviation.
- C. Meter weight: weight per meter = 0.02466*wall thickness * (outside diameter – wall thickness)
Deviation and tolerance
- A. Deviation: In the production process, because the actual size is difficult to meet the nominal size requirements, that is, often larger or smaller than the nominal size, so the standard provides for a difference between the actual size and the nominal size is allowed. The difference is called positive deviation, the difference is called negative deviation.
- B. Tolerance: The sum of the absolute values of positive and negative deviation values specified in the standard is called tolerance, also called “tolerance zone”.
Deviation is directional, that is, “positive” or “negative”; tolerance is not directional, therefore, the deviation value called “positive tolerance” or “negative tolerance” is wrong.
The delivery length is also called the user requirement length or contract length. The standard delivery length has the following provisions.
A. The usual length (also known as non-fixed length): where the length of the standard length range and no fixed length requirements, are called the usual length. For example, structural pipe standards: hot-rolled (extruded, expanded) steel pipe 3000mm ~ 12000mm; cold-drawn (rolled) steel pipe 2000mm ~ 10500mm.
B. Cut-to-length: cut-to-length should be within the usual length range, a certain fixed length size required in the contract. But in practice are cut out of the absolute length of the fixed length is unlikely, so the standard for the length of the fixed length of the allowed positive deviation value.
Take the standard of structural pipe as: production of fixed-length pipe than the usual length of the pipe into a larger rate of decline, the production enterprises to raise the price request is reasonable. The price increase is not consistent among enterprises, generally about 10% on the basis of the base price.
C. Times the length: times the length should be within the usual length, the contract should specify the single times the length and the total length of the multiples (for example, 3000mm × 3, that is, 3 times the number of 3000mm, the total length of 9000mm). In practice, the total length should be added to the allowable positive deviation of 20mm, plus each single times the length of the length should be left with a margin of cut. Take the structural tube as an example, it is stipulated to leave a margin of notch: 5~10mm for OD≤159mm; 10~15mm for OD>159mm.
If the standard does not have the deviation of the length and cutting allowance, the supply and demand sides should negotiate and specify in the contract. Double length with the same fixed length, will bring to the production enterprises into the material rate significantly reduced, so the production enterprises to raise the price is reasonable, the rate of increase with the fixed length rate of increase is basically the same.
D. Range length: range length in the usual length range, when the user requires a fixed range length, need to be specified in the contract.
For example: the usual length is 3000-12000mm, while the range of fixed length is 6000-8000mm or 8000-10000mm.
It can be seen that the range length is more lenient than the fixed length and times the length requirements, but much stricter than the usual length, but also to the production enterprises will bring the reduction of the material rate. Therefore, it is reasonable for the production enterprises to propose a price increase, and its price increase is generally about 4% on the base price.
Uneven wall thickness
The wall thickness of steel pipe cannot be the same everywhere, and there are objective wall thickness inequalities in its cross-section and longitudinal body, i.e. uneven wall thickness. In order to control this unevenness, there are steel pipe standards in the wall thickness unevenness of the allowable indicators, generally not more than 80% of the wall thickness tolerance (after consultation between the supply and demand for implementation).
In the cross-section of the round steel pipe there is the phenomenon of unequal outside diameter, that is, there is not necessarily perpendicular to each other, the maximum outside diameter and the minimum outside diameter of the difference between the maximum outside diameter and the minimum outside diameter is the ellipticity (or not roundness). In order to control the ellipticity, some steel pipe standards specify the allowable index of ellipticity, generally specified as not more than 80% of the outside diameter tolerance (after consultation between the supply and demand for implementation).
Steel pipe is curved in the direction of length, the curvature is expressed in figures called bend. The standard bending degree is generally divided into the following two kinds.
A. Local curvature: a meter-long straightedge against the maximum bend in the steel pipe, measured its chord height (mm), that is, the value of local curvature, the unit is mm / m, such as 2.5mm / m. This method is also applicable to the pipe end curvature.
B. The total length of the curvature: a thin rope, from the ends of the tube tension, measuring the maximum chord height at the bend of the steel pipe (mm), and then converted into a length (in meters) of the percentage, that is, the length of the steel pipe direction of the full-length curvature.
For example: the length of the steel pipe is 8m, measured the maximum chord height of 30mm, the tube should be the full-length bend: 0.03 ÷ 8m × 100% = 0.375%
End face: both ends of the steel pipe should be burr-free, chamfering should be R angle.
Surface: The outer surface of the product should not have pitting, bulging corrosion and other defects; otherwise it will affect the service life of the steel pipe (for example, if there is pitting on the inner surface of the steel pipe connected to the oilfield equipment, it will lead to leakage when pressure is applied during the operation).
Straightness of steel pipe
Straightness is the measurement of the deviation of the longitudinal axis of a pipe from a straight line. Straightness is measured by the ratio of the difference between the straightness of the pipe and its reference length.
The straightness requirements for steel pipe can be divided into three classes.
- Class I – Straightness is specified to be less than 0.02%. This level is typically required for large diameter pipelines used in high pressure and high temperature applications such as oil, gas, water and steam pipelines; also for marine applications such as mooring and anchor chains; offshore structures such as wind turbines, subsea risers ; nuclear power plants, etc.
- Class II – Straightness is specified as less than 0.08%. This level may be required for medium-sized pipelines used at low pressures (e.g., air conditioning systems or refrigeration systems); smaller diameter gas transmission pipelines that are not subject to severe bending forces but require a minimum bend radius for ease of installation, e.g., residential gas transmission pipelines that require small bends for installation in buildings; medium-sized pole and tower sections, etc., where there are no special requirements for wall thickness or minimum bend neck and therefore cannot use manual straightening machines (SMT) and other conventional methods to meet tighter tolerances.
Eccentricity of Steel Tubes
The eccentricity of a steel pipe is the difference between its shortest and longest diameters. The eccentricity of a tube should be less than 0.5 mm, but is usually measured with a concentricity gauge. It is an important parameter of steel pipe because it affects the weldability and mechanical properties of the finished pipe system.
Tolerance standard of steel pipe
Allowable deviation of outer diameter
Allowable deviation of standardized outer diameter
|Deviation grade||Allowable deviation of standardized outer diameter|
|D1||± 1.5%, min. ± 0.75 mm|
|D2||±1.0%, Minimum ± 0.50 mm|
|D3||± 0.75%, min ± 0.30 mm|
|D4||±0.50%, Minimum ± 0.10 mm|
|Allowable deviation of non standardized outer diameter|
|Deviation grade||Allowable deviation of non standardized outer diameter,%|
The allowable deviation of the outer diameter of steel pipes for special purposes and cold rolled (drawn) steel pipes can adopt absolute deviation.
The allowable deviation of wall thickness can be divided into standardized and non standardized. The standardized allowable deviation of wall thickness should be preferred.
Allowable deviation of wall thickness
|Deviation grade||Allowable deviation of wall thickness|
|S1||±15%, minimum ±0.6 mm|
|S2||A||±12.5%, minimum ±0.4 mm|
|B||+Positive deviation depends on weight requirements|
|S3||A||±10%, minimum ±0.2mm|
|C||+Positive deviation depends on weight requirements|
|S4||A||±7.5%, minimum ±0.15 mm|
|minimum 士0.2 mm|
|S5||±5%，minimum 士0.10 mm|
|Note: S is the nominal wall thickness of steel pipe, and D is the nominal outer diameter of steel pipe.|
Allowable deviation of recommended non standardized wall thickness
|Deviation grade||Allowable deviation of non standardized wall thickness，%|
The allowable deviation of wall thickness of steel pipes for special purposes and cold rolled (drawn) steel pipes can be absolute.
Steel pipes are generally delivered in the usual length. Generally, the length shall meet the following requirements:
Hot rolled (expanded) pipe: 3000-12000 mm;
Cold rolled (drawn) pipe: 2000-10500 mm.
The length of hot-rolled (expanded) short tube shall not be less than 2 m. The length of cold-rolled (drawn) short tube shall not be less than 1 m,
Fixed length and double length:
The fixed length and double length shall be within the normal length range. The allowable deviation of the full length is divided into three levels Cut allowance shall be reserved for each multiple length according to the following provisions:
Outer diameter ≤ 159 mm:5 – 10 mm;
Outer diameter >159 mm: 10 – 15 mm.
Allowable deviation of total length
|Allowable deviation grade of full length||Allowable deviation of total length.mrn|
Steel pipes for special purposes
For example, the length requirements of stainless acid resistant steel, extremely thin-walled steel pipes, small-diameter steel pipes, etc. can be specified separately.
Packing of stainless steel pipe
- Packed in wooden crates, wrapped in plastic, and suitably protected for sea-worthy delivery or as requested.
- Both ends of each crate will indicate the order no., heat no., dimensions, weight, and bundles or as requested.
Delivery of stainless steel pipe
- Pipes are supplied in hexagonal bundles or round bundles tied with steel strips.
- Weight of bundle – up to 5000 kg upon request of the customer.
- Each bundle is furnished with three tags.
Alloy steel pipe is a type of metal material that has many different uses and applications. It is important to know how to choose the right stainless steel pipe for your project, so we have outlined some tips below on how to do this effectively.
Stainless steel pipes are used for a variety of applications in both residential and commercial buildings. They come in many different sizes, shapes, and materials. This guide will help you choose the right kind of stainless steel pipes for your project.
Determine what your application requires.
When choosing a material, there are many factors that can affect your decision. These include:
- What is the application?
- Are there any regulatory or certification requirements?
- What are the conditions of use?
- How much do you want to spend?
Make sure the size is right.
When choosing a stainless steel pipe, you will need to make sure that the dimensions are the right size. If they are too small, then they will leak. If they are too big, then it will be too heavy and therefore not useful.
Consider the material
When you are looking for the best stainless steel pipe, it is important to know what kind of material you need. Stainless steel can be used for many different applications because of its durability and resistance to corrosion. If you are installing your own plumbing or repairing an existing system, it’s important that you choose the right material.
Pay attention to the surface finish of the pipe
The surface finish of the pipe is important to its corrosion resistance, aesthetics, ease of cleaning, ease of welding and joining by brazing. The two main types used for stainless steel pipes are bright or polished (also called mirror-finished) and brushed.
Brushed pipes have a matte finish that does not reflect light like a mirror finish does. A brushed surface reduces glare and makes it easier to clean dirt from the pipe. The brushed finish also provides better adhesion between solder or braze filler metal and the pipe surface than a brightly polished one does; this helps reduce cold flow during heating when joining dissimilar materials together with solder brazing techniques.
You need to distinguish between different kinds of stainless steel pipes, choose the right grade and surface finish and look for a professional supplier that pays attention to quality.
Stainless steel pipes are used in a wide range of applications. They are easy to clean, maintain and install. The material is extremely durable and easy to work with, making it an ideal choice for many projects.
To choose the right grade and surface finish, you need to distinguish between different kinds of stainless steel pipes. There are different types of stainless steel pipes available on the market today, each offering its own advantages over others at different price points.
Check to see if the surface is coated
The most important thing about a coating is that it should be able to withstand scratches and damage, but not be so brittle that it will break off on its own. In general, stainless steel pipes with thicker coatings are more reliable than those with thinner ones.
If a pipe does have a coating and you want to remove it for any reason, this should be done carefully by someone who knows what they’re doing (like an engineer). It’s also important that they understand how much of the current coating layer has been removed before they start working on the next one—if they don’t do this correctly then you could end up with even less protection than before!
You need to consider some important things before you choose the right pipes.
- Corrosion resistance: It is one of the most important factors in selecting a pipe that will last longer. The stainless steel pipes are resistant to corrosion, and they do not react with any chemicals or other substances, thus providing a healthier environment for drinking water and other liquids.
- Temperature resistance: Stainless steel has excellent thermal conductivity, which means it can easily transfer heat from one place to another at a faster rate than other materials such as copper or aluminum. This makes it ideal for industrial applications where high-temperature processing is required because it prevents oxidation during high-temperature operations.
Choose a reliable stainless steel pipes manufacturer
A good manufacturer will have a reputation for making high-quality products. If you’re looking at some stainless steel pipe, make sure it’s from a company that makes tubing or piping of other types as well (such as copper). This will help ensure that they have experience in the industry and know what they’re doing.
A good manufacturer also has an established distribution network—so you know where to find them when you need something else. They should also have a customer support team with representatives who are available either by email or phone so you can get answers when needed.
If all else fails, ask around! See what other people say about the manufacturer before deciding which one is right for your needs.
Select the right stainless steel pipes manufacturer.
You should also find out whether the manufacturer has a good reputation in the industry. The best way to do this is to ask around, including talking with other people who have recently bought stainless steel pipes from the same manufacturer. You can also check reviews and testimonials online.
If you find that the manufacturer has really bad reviews or doesn’t have any reviews at all, then it might not be worth using them as your supplier. On the other hand, if they do have great reviews and lots of happy customers, then they could be an excellent choice for you too!
Stainless steel pipes are a great choice for many applications. They provide durability, strength and longevity while remaining easy to work with. If you’re looking for a material that is resistant to corrosion or rusting, consider using stainless steel pipes in your next project! For free stainless steel pipe solutions, please contact us.
Source: China Piping Solutions Provider – Yaang Pipe Industry Co., Limited (www.epowermetals.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, and Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels, and other industries.)
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