Knowledges of seamless steel pipes

Steel pipes are ubiquitous and can be found underground and within residential walls, laboratories, and commercial and industrial structures. The pipes transport fluids including water, natural gas, waste and air. Three manufacturing methods exist to produce steel pipes. Seamless steel pipes are produced using an extrusion mold. Welded steel pipes are produced by rolling a sheet of steel into a tube and welding the seam.
The seamless steel pipe manufacturing process starts with a solid, round steel billet. This billet is then heated to great temperatures and stretched and pulled over a form until it takes the shape of a hollow tube. As other steel pipe suppliers will tell you, there are three great advantages to making a pipe in this way.

Increased Pressure Ratings

The greatest advantage of seamless steel pipes are their increased ability to withstand pressure. The weakest point in a welded steel pipe is the welded seam. But because a seamless steel pipe has not been welded, it doesn’t have that seam, making it equally strong around the entire circumference of the pipe.
It is also much easier to determine pressure calculations without being required to take weld quality into consideration.
Although seamless pipe can sometimes be more expensive than welded pipe, this increased ability to withstand pressure allows you to use pipes that are thinner and lighter, which can help cut down on expenses.

Uniformity of Shape

Because welded seam pipe is wrapped around another form before it is welded, and because welding adds heat, stress and other extraneous variables to the forming process, it can never be as round as seamless steel pipe.
Seamless steel pipe is a continuous extrusion of the alloy, meaning that it will have a round cross section that you can count on, which is helpful when you’re installing pipes or adding fittings.

Strength Under Loads

Seamless steel pipe can sometimes be more expensive than other forms of steel pipe, but it’s also more reliable.
This is because it has greater strength under loading. Empty pipe must always support its own weight, but when a pipe is filled with material–or under load–it must also support that weight as well. Pipe failures and leaks in welded pipes usually occur at the welded seam. But because seamless pipe doesn’t have that seam, it isn’t subject to those failures.
These benefits make seamless steel pipes the preferred material in an array of commercial pipe applications, including ship building, pipelines, oil rigs, oil field equipment, pressure vessels, machinery parts and offshore rigs. An additional benefit of seamless steel pipe is that they perform well in harsh conditions, which means that they can be used in extremely cold or hot environments.

If you’re considering seamless steel pipes for your next commercial pipe project, please get in touch with us and request a quote. As a leading international steel pipe supplier, we can provide you with the products you need and quickly ship your order to anywhere in the world.

The developments for steel pipes

Steel pipes products as an important part in national economic development plays a significant role in the molding process due to the welding method and the use of different shapes into large-diameter tube seamless, straight seam steel pipe, spiral welded pipe.Divided into high-frequency straight seam steel pipe straight seam steel pipe, large diameter LSAW steel pipe.Currently the world’s steel industry is the general trend: the growth rate of output pipe seamless pipe faster than the growth rate;

Steel pipe production proportionately much larger than seamless; seamless in all areas of market competition;

tube in the pipe, ERW steel pipe production on the dominant and long-distance oil and gas pipelines, city gas pipelines within the field of use LSAW pipe and spiral SAW pipes for the market.

Pipe is accompanied by the development of technology and seamless and progressive.Pipe in some areas will be seamless to gradually replace the inevitable trend, the key factor is the continuous improvement of product quality and lower manufacturing costs. Improve the quality of welded products, mainly rely on three technological advances: First, iron and steel smelting technology, and second, hot-rolled strip technology, third, steel manufacturing process.In Western countries, focused on broadening the use of ERW pipe area, the North American representative of the United States as the key development ERW OCTG range of applications, in the 1980s in the 3000m deep wells have been commonly used ERW casing;

To Germany on behalf of Europe,focus on developing application of boiler tubes, ERW pipe production in the low-pressure boiler pipe applications are common, accounting for more than half of the total boiler tubes, also used by some high-pressure boiler tubes ERW pipe.Asia to Japan, South Korea, represented almost fully developed the application of ERW pipe; South Korea, the country’s total steel pipe more than 98% of total output, while the ERW pipe and pipe production account for more than 90%; Japan, due to weldingrapid advances in technology management and production costs down, and gradually replace some of the UOE pipe and seamless pipe.

Bound as a substitute in the future development trend of seamless pipe, welded steel pipe production technology manufacturing company has been the escalation of the future will use the product line and more comprehensive, higher quality pipe.
Q215, Q235A, B steel and 20 steel, diameter 63.5-219.0mm.

On the tube bending, end with the vertical center line, ellipse there are certain requirements, usually the pressure and flattening test.

How to make seamless pipes?

According to manufacuring process of seamless steel pipes, seamless steel pipes can be divided into hot rolled seamlesssteel pipes and cold drawn seamless steel pipes.

Cold drawn seamless steel tube process - Knowledges of seamless steel pipes
Process flow chart of cold drawn seamless steel pipe
Cold drawn seamless steel pipes process:

round tube → heating → perforation → Heading → annealing → pickling → oiled (copper) → multi-pass cold drawn (cold rolled) → blank tube → heat treatment → straightening →hydrostatic testing (testing) → mark → storage.

The general cold strip mills, volume should go through continuous annealing (CAPL unit) to eliminate cold hardening and rolling stress, or batch annealing reach the mechanical properties of the corresponding standard specifies. Cold rolled steel surface quality, appearance, dimensional accuracy better than hot-rolled plate, and right-rolled thin product thickness is about 0.18mm, so the majority of users favor.

Hot rolled seamless steel pipe deformed process

Hot-rolled seamless steel pipe production base deformation process can be summarized as three stages: perforation, extension and finishing.

Hot rolled seamless steel pipe deformed processes - Knowledges of seamless steel pipes

The main purpose of the perforation process is to become a solid round billet piercing hollow shell. Capillary in the specifications, accuracy and surface quality can not meet the requirements of the finished product, further improvements are needed to deform the metal through. The main purpose of the stretching machine is further reduced sectional view (main compression wall) for a larger axial extension, so that the capillary improved dimensional accuracy, surface quality and organizational performance.

After stretching machine rolled steel pipe shortage collectively need further molding mill in order to achieve the requirements of the finished pipe. Rolled steel due to pass in the method widely used in the production of seamless steel tubes.

So far, due to the method pass rolling steel can be divided into two categories: core pension without rolling rolling (hollow body rolling), and with the mandrel. Sizing machines, reducing mill and stretch reducing mill belonging to the hole without mandrel type continuous rolling mills are generally coffin. Its main purpose is to reduce the diameter of the deformation process or sizing get finished steel, the wall thickness of process control, can make thinning, thickening or nearly unchanged.

All the traditional hole-type rolling machine with mandrel belong to extend machine. The main purpose is to reduce the deformation process perforated capillary wall thickness and outer diameter roll passes in the deformation zone and the mandrel posed, for a larger axial extension. At the same time a certain improvement in the organization, performance, accuracy, surface quality.

Difference between hot rolled and cold formed steel

There are several major differences between hot rolled steel and cold rolled steel, all relating to the ways these metals are processed at the mill.

Hot rolled steel
Hot rolled seamless steel pipe 1 - Knowledges of seamless steel pipes

Hot-rolled is with continuous casting slab or blooming slab as raw material, after reheating furnace heating, high pressure water descaling into roughing mill, roughing material by the cutting head, tail, and then enter the finishing mill, the implementation of a computer-controlled rolling made the final rolling after coiling after the laminar cooling (computer-controlled cooling rate) and the coiler, straight hair volume. Straight hair the volume of the head, the tail is often poor, was a tongue-and fishtail, thickness, width, precision the edge often there is a wave-shaped, folding, pyramid defects. Coil weight heavier coil diameter of 760mm. (Normal pipe industry prefer to use.) Straight hair volume by the cutting head, tail cutting, trimming, and multi-pass straightening flat finishing line treatment, a cutting board or heavy volume, that is, to become: hot-rolled steel plate, flat hot-rolled steel coils, slitting with other products. Serve hot finishing volume descaled, pickled and oiled hot-rolled pickled coils.

Seamless pipe extrusion

Extrusion method refers to the metal blank into the extruder barrel, extrusion molding and extrusion rod composed of “closed” container by applying pressure to force the metal extruded rod extrusion die orifice outflow from, and access to metal plastic molding the method, which is a historic seamless manufacturing methods. 

According to the direction of extrusion and metal lever urging the relative relationship between the direction of flow, extrusion method can be divided into two kinds of forward extrusion and backward extrusion. Forward extrusion direction of force and metal flowing in the same direction, backward extrusion opposite. Anti- extrusion with extrusion pressure is small, extrusion ratio, extrusion speed, extrusion temperature can be reduced to improve the extrusion conditions, easy to implement isothermal / isobaric / constant extrusion, improve product performance and dimensional accuracy organizations, can reduce the margin squeeze at the end of the metal pressure, improve metal yield, etc.; but its operation is relatively inconvenient, and the product section size by extrusion rod size restrictions. 

Seamless pipe extrusion production process
Perforated tube round → heating → three-roll rolling, rolling or extrusion → detached → sizing ( or reducing ) → cooling → straightening → hydrostatic test ( or testing ) → mark → storage rolling without the raw material is slit tube round tube, pipe cutting machine embryos to go through cutting the growth of about 1 m blank, and by conveyor belt to the furnace heating. Heating the billet is fed into the furnace, the temperature is about 1200 degrees Celsius. Fuel is hydrogen or acetylene. Furnace temperature control is the key issue. Circle tube came out through the pressure punching machine wear air. Generally more common punch is tapered roller punching machine, punching machine such high production efficiency, product quality, perforated expanding volume, you can wear a variety of steels. 

After perforation, round tube has been three roll rolling, rolling or extrusion. Squeeze off the tube after sizing. Sizing mill rotating at high speed through a cone drill holes into the billet to form pipe. Pipe diameter from the sizing mill to determine the length of the drill diameter. The pipe sizing after entering the cooling tower through water cooling pipe after cooling, will be straightening. Steel belt sent by straightening the metal detection machine ( or water pressure test ) for internal testing. 

If the pipe internal cracks, bubbles and other problems will be detected. Steel quality even after rigorous hand-selected. Steel quality, the use of spray paint number, size, production batch number. Hanging by a crane into the warehouse.

Cold formed steel
ASTM A179 cold drawn steel tube - Knowledges of seamless steel pipes

Cold formed is as raw material, after oxide removal by pickling tandem cold formed finished rolling hard roll, work hardening due to the volume of the rolling hard due to the continuous cold deformation strength, hardness rise, tough Plastic indicators declined, stamping performance will deteriorate, and can only be used for simple deformation of the parts. Rolling hard roll can be used as the raw material of the hot-dip galvanizing plant, hot dip galvanizing line set annealing line. Rolling hard roll weight is generally 6 to 13.5 tons, the coil diameter of 610mm. The general cold strip mills, volume should go through continuous annealing (CAPL unit) to eliminate cold hardening and rolling stress, or batch annealing reach the mechanical properties of the corresponding standard specifies. The cold-formed steel sheet surface quality, appearance, dimensional accuracy superior to the hot-rolled sheet, and right rolling thin product thickness to about 0.18mm. 

Difference between hot-rolled and cold-formed:

1, cold formed steel to allow cross-section a local buckling, which can make full use of the rod buckling bearing capacity;-section hot rolled steel does not allow local buckling occurs.

2, the residual stress of the hot-rolled steel and cold-formed steel produced by different reasons, so the distribution of the cross section is also very different. The residual stress distribution in the cross section of cold-formed steel bending, residual stress distribution in the hot rolling steel or welded steel cross-section is a film type.

3 free torsional stiffness of hot-rolled steel, cold-formed steel, the torsional properties of hot-rolled steel is better than cold-formed steel.

Steel pipe cutting machine

ERW cutting - Knowledges of seamless steel pipes

Steel pipe cutting machine includes laser cutting machine, laser cutting machine square tube, oval tube laser cutting machine.

Seamless steel pipes by Standard

Seamless pipes by standards include: ASTM, JIS, DIN, Customers for international

usage automotive industry - Knowledges of seamless steel pipes
  • Seamless pipes Specifications and Execution Standard
  • ASTM Standards for steel pipes
  • How to make seamless pipe & tubes?
  • ASTM A106: Seamless Carbon Steel for High Temperature Service
  • ASTM A179– Cold-drawn Low-Carbon Steel Heat-Exchanger and Condenser Tubes
  • ASTM A192– Seamless Carbon Steel Boiler Tubes for High Pressure
  • GB 3087 – Low and medium pressure boiler seamless pipe

Pipe cutting machine processing has a wide range to meet user tube, square tube, oval shaped tube cutting and processing. 

Advantages of steel pipe cutting machine:
  • cut the head of a number of different directions, cylindrical holes intersecting lines of different diameters, to meet with the head of the eccentric and non-eccentric axis intersects the vertical axis of the branch pipe condition.
  • cut the ends of the cylinder in the branch pipe ends intersecting line to meet the head of the branch pipe axis and the vertical axis intersects eccentric and non- eccentric, inclined intersection conditions. 3, cut beveled end surface pipe ends.
  • cut with a circular intersection in charge of branch pipes intersecting line ends.
  • change the angle of the cutting bevel surface.
  • cut a square hole in the tube, kidney-shaped holes.
  • steel can be cut off.
  • a variety of graphics in square tube surface.
Steel pipe cutting machine for material widely:

for stainless steel, carbon steel, alloy steel, aluminum, copper, titanium and other metal pipes, all kinds of high hard brittle alloy material has a very excellent processing results.

Steel pipe cutting machine applications: widely used in petroleum exploration, lamps, metal processing, metal and other industries.

seamless process Acid Cleaning Workshop - Knowledges of seamless steel pipes
Acid cleaning workshop
seamless process Cold Drawn Workshop - Knowledges of seamless steel pipes
Cold Drawn Workshop

seamless process ECT 620 Eddy Currentautomatic Test System - Knowledges of seamless steel pipes

ECT-620 Eddy Test System

seamless process Feeding intake - Knowledges of seamless steel pipes
Feeding intake
seamless process Heat Treatment Workshop - Knowledges of seamless steel pipes
Heat Treatment Workshop
seamless process Ingot heating - Knowledges of seamless steel pipes
Ingot heating
seamless process cutting - Knowledges of seamless steel pipes
Pipe cutting
seamless process Beveld cut - Knowledges of seamless steel pipes
Pipeline Beveled Ends
seamless process packing - Knowledges of seamless steel pipes
Well packing
seamless process Ultrasonic inspection of seamless pipes - Knowledges of seamless steel pipes
Ultrasonic inspection
seamless process ultrasonic test on astm a335 p22 pipe - Knowledges of seamless steel pipes
Ultrasonic test on A335 pipe
seamless process Non destructive testing of seamless steel pipe - Knowledges of seamless steel pipes
Non destructive testing

Seamless steel pipe quality testing is a very important step, and for its detection method is also very particular to now all three – ultrasonic testing, Eddy current testing, magnetic flux leakage testing, specific circumstances are as follows:

Yaang has taken a leading role in steel market for many years by providing technical service support to customers through our qualified and experienced staff. We promise that our products have been certified by ISO/ API/ ASTM authority institute.

They are produced according to given standard and we accept you or the 3rd party inspection at any time. Specified NDT/ PT/ HT/ AH/ TPI also accepted by Anson as per client’s request.

The application and uses of steel pipe

Steel pipe is the most commonly and widely used in the gas project field. 
Its main advantages are: high strength, good toughness, bearing stress, impact resistance and rigor, good plasticity, ease of welding and thermal processing, thin wall thickness, to save metal. But its poor corrosion resistance, need to have proper anti-corrosion measures. Steel pipe used in gas engineering are generally made of high quality low carbon steel (Q235) or low-alloy steel (16Mn).

Steel construction is the construction of a new type of energy saving and environmental protection system, known as the 21st century “green building”. The steel construction is light weight, high strength, good seismic performance, energy saving, recycling, building structure, in line with the requirements of the development of energy efficient building and sustained and healthy economic development. The biggest advantage of the steel structure is to bring people to the building function, sensory requirements and economic requirements of a perfect combination. Steel tube structure, with its superior performance in recent years, application of the rapid development of the range of applications involving almost all structural areas, including housing construction, bridges, dams, offshore platform structure and tower masts and so on.

Steel with hollow sections is conveying fluid, such as the transportation of oil, gas, gas, water and some solid materials, pipes, etc.. Compared with the round steel and other solid steel in the flexural torsional strength, light weight, is an economic cross-section steel, widely used in the manufacture of structural parts and mechanical parts, such as drill pipe, automotive transmission, bicycle rack and construction using steel scaffolding. Steel pipe manufacturing annular parts, can improve material utilization, and simplify the manufacturing process, saving material and machining time, such as rolling sleeve ring, jack sets, has been widely manufactured steel pipe.

Large-diameter steel pipe with good adhesion, corrosion resistance, can be resistant to acid, alkali and other chemical corrosion, non-toxic, does not rust, wear resistance, impact resistance, strong permeability, smooth pipe surface will not adhere to any substance, can reduce the transmission of resistance, large diameter steel pipe improve flow and transmission efficiency and reduce the delivery pressure losses. Solvent-free coating, no oozing substance, and thus will not the transmission medium of pollution in order to ensure the purity and health of the fluid at -40 ℃ to +80 ℃ range of thermal cycles used interchangeably, not aging. no cracks, and thus can be used in the cold zone and other harsh environment. Large-diameter steel pipe is pipe that outside diameter is above 1000MM, large diameter coated steel pipe is coated with plastic on the basis of large diameter spiral welded pipe and high-frequency welded pipe from the solvent-free coating, small-diameter steel pipe no oozing substance and therefore not pollution transport media, thus ensuring the purity and health of the fluid, -40 ℃ to +80 ℃ range of thermal cycles used interchangeably, no aging, no cracks, and thus in the cold zone and other harsh environments to use.

The large diameter coated steel pipes are widely used in tap water, natural gas, petroleum, chemical, pharmaceutical, telecommunications, electricity, large diameter steel marine engineering field generally less than the outer diameter of the tubes 89 are collectively referred to as small-diameter steel pipe.

Steel pipe length requirement

The length of steel pipe exceeds the requirements, the ultra is poor said feet long, superimposed differential said short feet.

  1. tube length exceeded.
  2. Rolling unstable.
  3. did not control when cutting and so on.

Inspection found: 
long tube and cut or sentence, short feet tube commuted or sentenced to waste. Control points have detailed provisions, the factory strictly according to the rules and post operation rules, technology regulations. 

In addition to the online testing equipment (temperature, thickness, length, speed, etc.) by computer for slab and steel pipe production for micro testing and control, steel, pipe rolling, pipe processing three main factory inspection division also specially equipped with the technology, their duty is to slab, pipe rolling, pipe processing and production of each link, process, conduct supervision and inspection, and fill in process inspection record, for reference.

Steel pipe is not straight along the longitudinal direction of the pipe ends or rendered goose -shaped bend called “goose head bent.”

  1. artificial heat seized when the local water caused.
  2. When properly adjusted straightening, straightening rolls badly worn.
  3. Sizing machining, assembly and improperly adjusted.
  4. lifting and transportation caused bent.

Wall thickness tolerance of seamless steel pipes

Seamless steel pipes are extensively applied for the nuclear device, gas, petrochemical, ship building and boiler industries. seamless steel pipes dominates 65% of market share in Chinese boiler industry.

Types Sizes allowed tolerance
Ordinary steel pipe Senior steel pipe
Hot rolled Out diameter <50 ± 0.50 mm ± 0.40 mm
≥50 ± 1 % ± 0.75 %
Wall thickness <4 ± 12.5 % ± 10 %
4-20 +15%
± 10 %
≥20 ± 12.5 % ± 10 %
Cold drawn Out diameter 6-10 ± 0.20 mm  ± 0.10 mm
>10-30 ± 0.40 mm ± 0.20 mm 
>30-50 ± 0.45 mm ± 0.25 mm 
>50 ± 1 % ± 0.5 %
Wall thickness ≤1 ± 0.15 mm ± 0.12 mm
1-3 + 15 %
– 10 % 
± 10 %
>3 + 12.5
– 10 %
± 10 %

Stress relief annealing of seamless steel pipe

Stress relief annealing of seamless steel pipe: annealed to remove stress and residual stress in the casting of memory due to plastic deformation processing, welding, etc. caused by the conduct referred to as stress relief annealing.
Cold drawn seamless steel pipe deformation (stress relief annealing phase transition does not occur), can not reach the surface finish and dimensional accuracy requirements, they can not achieve strength index components; deformation is too large, seamless steel ductility, toughness reduce excessive Moreover, elongated grains excessively pulled, the formation of fibrous tissue, metals having a significant anisotropy. Cold drawn seamless steel tube axially parallel to the elongated direction of the grain, increased strength; cold drawn seamless steel pipe radially, perpendicular to the elongated direction of the grain, but lower strength, maximum stress and the hydraulic cylinder being present in the radial direction of seamless steel tubes on, so much to give full play to the deformation properties of cold drawn tubes unfavorable. For the fibrous tissue that appears in the steel and dislocations, vacancies and other crystal defects are generally taken annealing or normalizing heat treatment methods to eliminate them. The purpose is to refine the grain annealing, eliminating tissue defects, reduced hardness, improved ductility, but also facilitate cold. 
Process of stress relief annealing: the workpiece was slowly heated to Ac 1 or less 100 ~ 200 ℃ (500 ~ 600 ℃) holding a certain time (1 ~ 3h) followed by slow furnace cooling to 200 ℃, baked and then cooled. Steel is generally 500 ~ 600 ℃,Iron is generally 500 ~ 550 ℃ likely to cause pearlite graphitization than 550. Weldment generally 500 ~ 600 ℃. 
Scope: the elimination of casting, forging, welding parts, cold stamping and machining the workpiece residual stress in order to stabilize the size of steel, reducing distortion and prevent cracking. 
Purpose: cold drawn seamless steel pipe were needed after stress relief annealing, to eliminate the residual stress of the material, improve the organization of materials, improved plastic material, so as to achieve the purpose of preventing seamless steel pipe fracture failure occurs.

Seamless steel pipes Execution Standard

A seamless steel pipe, as the name suggests, is a pipe without a seam or a weld-joint. Seamless pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow — liquids and gases (fluids), slurries, powders and masses of small solids.

It can also be used for structural applications; hollow pipe is far stiffer per unit weight than solid members. Seamless pipe is thought to be able to withstand higher pressure, higher temperatures, higher mechanical stress and a corrosive atmosphere. It can be found in a wide range of applications such as in oil and gas, refinery, petrochemical, chemical, fertilizer, power, automotive, bearing, mechanical and structural.

The production of our seamless steel pipes are tightly regulated and all of the pipes we stock have been fully tested to international standards to ensure we only supply the highest quality products.

Available Specification standaard

We can makes and markets cold-drawn and hot rolled seamless steel pipes and cold-drawn special-section seamless pipes which are widely applied in the industries of petrochemical, boiler, automobile, mechanical, construction.


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

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 Cold-drawn Carbon Steel Feedwater Heater Tubes ASTM A556 10.3~426 x 1.0~36 A2, B2

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,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 lenght
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) specifies 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 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)
G3462(STBA22, STBA23)
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 high quality carbon structural. GB5310 19.05~114.3 x 2.0~14 20G, 20MnG, 25MnG, 15MoG, 20MoG, 12CrMoG, 15CrMoG(T12/P12), 12CrMoG, 12Cr2MoWVTiB.

Steel pipe derusting methods

Generally, using chemical and electrolysis ways to do pickling processing pipeline anti-corrosion chemical pickling can remove the oxide scale, rust, old coatings, and sometimes used as a sand-blasting after reprocessing.

Although chemical cleaning can reach the surface cleanliness and roughness, the bolt pattern light, and easy to pollute the environment.

Spray radio rust
Spray radio rust by high-power seamless steel pipe motor-driven jet (throw) shooting leaves high-speed rotation, making the grit, steel shot, wire, minerals and other abrasive under the centrifugal force on the steel pipe surface spray (throwing ) irradiated, not only can completely remove the rust, oxides and dirt, and the steel abrasive violent shocks and the role of friction, but also to achieve the required uniform roughness. Spray (throwing) radio rust, can not only expand the physical adsorption of the tube surface, and can enhance the mechanical adhesion of the coating with the tube surface. 
Therefore, spray (throwing) radio rust pipeline corrosion ideal rust ways of. Generally, shot peening (sand) blasting is mainly used for pipe surface treatment, shot blasting (sand) blasting is mainly used for pipe outer surface of the processing. Using spray (throwing) radio rust should pay attention to several issues.

Instrument rust
Using instrument such as wire brush to polish the steel surface to remove loose or the tilt of the oxide scale, rust, welding slag. Rust can reach Sa2 grade manual tools, power tools rust can be achieved Sa3 level, if the steel surface attached to a solid oxide scale, the result is not satisfactory tools rust, amounting to less than anti-corrosion construction requirements anchor pattern depth pickling.

naked packing seamless pipe - Knowledges of seamless steel pipes

Naked packing A335 P5 pipes

crate packing seamless pipe - Knowledges of seamless steel pipes

Crate packing ASTM A213 T5b tubes

packing u bend tubes - Knowledges of seamless steel pipes

Packing the U-bend tubes

There are probably hundreds of different methods for packing a steel pipe, and most of them have merit, but there are two principles that are vital for any method to work prevent rusting and Sea transportation security.

Characteristics of seamless steel pipes

Seamless steel pipes process performance test: flattening test, tensile test, impact test, flaring test, hardness test, metallographic test, bending test, nondestructive testing (including eddy current X-ray and ultrasonic testing). 

Seamless steel pipes chemical analysis: the chemical composition of the material for chemical analysis, chemical composition to meet the standard requirements. 

Seamless steel pipes pressure and hydrostatic test is for pressure tube by into the hydrostatic test, which do not maintain the prescribed pressure value not less than 5 seconds, not to disclose, the regular supply hydraulic pressure test is 2.45MPa pressure The pressure test is P = 0.5MPAa. 

The corrosion test: industrial corrosion-resistant steel pipe according to standard regulations or agreement between the corrosion of steel pipe corrosion resistance test, no intergranular corrosion. 

Characteristics of seamless steel pipes

  • the outer diameter is smaller.
  • High precision can do small quantities of raw.
  • cold drawn steel pipe with high precision and good surface quality.
  • steel pipe cross area is more complex.
  • steel pipe superior performance, relatively dense metal.

Seamless steel pipe pressure

Composed piece of seamless steel pressure pipes are generally standard, so the pressure piping components are primarily designed selection, pipeline pressure levels to determine their standard of its standard level is determined.

Pipe pressure rating: usually determined by a common pipe fittings standard nominal pressure rating and wall thickness of the pipe pressure rating that can reflects the parameters characteristic called pipe pressure rating. The customary to simplify the description, often to the pipe fittings nominal level called pipeline pressure rating. Pressure levels to determine the basis for the design pressure of the pipeline, but also the core design. It is the pressure piping, pressure piping design stress check preconditions pressure pipeline is an important factor in investment in infrastructure and pipeline reliability impact.

Different materials, the mechanical properties are different, the temperatures are in the standard – the corresponding value on the pressure gauge is not the same. Therefore, before determining nominal pipe material pipeline should first determine its components. It is determined by the choice of material design temperature, design and operation of the pressure medium. With forging material, while valve multi-cast material. No matter what material standard used, they should be the same level of material that has the same operating conditions, such as strength and adaptability; note pipe, plate, bar, cast material compatibility.

Allowable stress of the material refers to the material strength index value divided by the appropriate factor of safety obtained. Mechanical performance materials are yield limit, ultimate strength, creep limit, fatigue limit, these indicators reflect different states were failures limit. To ensure reliable operation of the pipe strength, the pipe element is often restricted to a value of stress at each intensity index, the value is the allowable stress. When the pipe element stress exceeds the allowable stress values, it believes its strength can not be guaranteed. So, to say, material allowable stress level is to determine the basic parameters of the pipe wall thickness.

Seamless stainless steel pipe

Seamless stainless steel pipe - Knowledges of seamless steel pipes

It is the resistance of air, steam, water and other weak corrosive media and acid, alkali, salt and other chemical etching medium corrosion of steel pipes. Also known as acid – resistant stainless steel.

Seamless stainless steel pipe 304 0Crr18Ni9 - Knowledges of seamless steel pipes
304 (0Crr18Ni9) Seamless stainless steel pipe

Stainless steel pipes are safe and reliable, environmental health, affordable, and the thin wall of the pipe as well as new and reliable, the successful development of a simple and convenient connection method, which make it more irreplaceable advantages. It will be more and more engineering use and become increasingly popular, and prospects. 

Features of seamless stainless steel pipes: 
First, the thicker the wall thickness of the product, it is more economical and practical, the wall thickness of the thinner, its processing costs will rise substantially;
Secondly, the process of the product determines its limitations, the low accuracy of the general seamless tube: non-uniform wall thickness, the appearance of low brightness tube, the high cost of fixed length, and within the appearance of pitting, black spots difficult to remove; Third, the detection and plastic must be offline processing. So it is at high pressure, high strength, the mechanical structure timber reflects its superiority. 
The corrosion resistance of stainless steel seamless pipe depends on the alloying elements contained in the steel. Chromium is the basic elements of corrosion resistance for the stainless steel, about 12% the amount of chromium in the steel, chromium and oxygen role in the corrosive medium, the steel surface to form a thin oxide film (passive film) matrix can prevent the steel from further corrosion. Removing chromium, stainless steel seamless pipe commonly used alloying elements there are nickel, molybdenum, titanium, niobium, copper, nitrogen, etc., to meet the requirements of the various uses of the organization and performance of stainless steel.

Material stainless steel grades:

Also known as “marine grade” stainless steel due to its increased ability to resist saltwater corrosion compared to type 304. SS316 is often used for building nuclear reprocessing plants.

  • 304/304L Stainless Steel
  • 316/316L Stainless Steel
  • 310S Stainless Steel
  • 317L Stainless Steel
  • 321/321H Stainless Steel
  • 410 Stainless Steel
  • Duplex 2205 (UNS S31803)

Galvanized steel pipe

What is Galvanized Steel Pipe?

Galvanized steel can be made into a strong plumbing or tubing material — one that resists corrosion from exposure to water or the elements. It has been used used for water-supply pipes or as a strong tubing for outdoor applications.

It is most commonly used for outdoor construction like fences and handrails, or for some interior plumbing. It is also sometimes called galvanized iron pipe. Galvanized steel pipe has been coated with a layer of zinc. The zinc provides a barrier against corrosion so that the pipe may be exposed to the outdoor environmental elements. The protective barrier proves equally effective against damage from indoor humidity.

Galvanized steel pipe is covered with a zinc material to make the steel pipe more resistant to corrosion.

History of Galvanized Steel Pipe

The process of galvanization was first discussed by scientists in the 1770s, nearly 60 years before it was finally introduced in the 1830s. French engineer Stanislaus Tranquille Modeste Sorel took out the first patent for the process in 1937, and began manufacturing it soon after. By the 1850s, Europe was producing galvanized steel out of manufacturing plants located around the continent. The United States followed shortly thereafter, opening its first plant in the 1870s.

To create galvanized steel pipe, steel materials are placed into a molten bath of zinc. This process is also called hot dip galvanization. The two metals are chemically bound to one another in this process, and will therefore never separate, resulting in a more resistant and longer lasting version of steel.

Uses Galvanized Steel Pipe

Galvanized Steel Pipe is used in a variety of settings. Until about 30 years ago, galvanized steel was utilized for water supply pipes in construction. It is used in outdoor applications wherever the strength of steel is desired, such as fence posts and rails, scaffolding and as protective railings.

  • Galvanized steel clamp connection technology applications
The common trouble in using

When used as water pipe, the zinc barrier coating tends to react to the minerals in the water, often causing plaque to build up inside of the pipe. This impedes the water flow and, in severe cases, may lead to burst pipes. Galvanized piping is connected with threaded fittings that may also introduce leaks into the plumbing if not properly fitted.

Types of galvanized

There are a number of methods of applying zinc coatings and each will determine the coating’s thickness and its ultimate durability in a specific environments The most commonly encountered types of zinc coatings are:

  • Zinc electroplating
  • Mechanical plating
  • Continuously galvanized sheet
  • Continuously galvanized wire
  • Galvanized pipe and tube
  • General or hot dip galvanizing
What is Hot-Dip Galvanizing?

Galvanized pipe for water banner - Knowledges of seamless steel pipes
Hot dip galvanizing steel pipe with threaded end

Hot-dip galvanizing (HDG), as referenced is the process of dipping fabricated steel into a kettle or vat of molten zinc. While the steel is in the kettle, the iron metallurgically reacts with the molten zinc to form a tightly-bonded alloy coating that provides superior corrosion protection to the steel.

Hot-dip galvanizing is a form of galvanization. It is the process of coating iron, steel or aluminum with a thin zinc layer, by passing the metal through a molten bath of zinc at a temperature of around 860 °F (460 °C).

When we discuss seamless steel pipe, Seamless steel pipe is with a wide range of applications in our construction industry. In general, Galvanized seamless tube is the hot dip galvanized and electro-galvanized two categories.

The first to introduce hot-dip galvanizing, including wet, dry the, lead, zinc, oxidation-reduction method, etc., the process is very complex, the need for technical maturity to complete. Steel Pipe acid leaching after cleaning, the specific method used to activate the surface of the tube improve the quality of zinc, is not the same, hot dip galvanized main difference.

I do not know understand if understand the electro-galvanized zinc coating surface and compared to a very smooth and dense, homogeneous; the characteristics of the electro-galvanized with good corrosion resistance and mechanical properties; Production is now mainly used in dry and oxidation-reduction method. Coating on one side, the internal and external surfaces of the thickness of the coating on different double-sided smooth coating, and thin-walled tube galvanized to complete this method.

Zinc consumption 60% to 75% lower than the hot-dip galvanizing. Electro-galvanized in the operation of technical and general than there is a certain complexity, which requires high technology and conditions in order to complete.

Hot dip galvanized coating 1 - Knowledges of seamless steel pipes

Precision Seamless Pipe

Precision seamless pipe is a pipe material producing by a cold drawn process with high precision and high-quality finish.

precision seamless tubes 1 - Knowledges of seamless steel pipes

CDS is popular in the hydraulics, being used to make hollowed chrome plated telescopic cylinders and hydraulic rods. It is also popular for large bore, heavy walled, high pressure hydraulic cylinders. Cold Drawn Seamless tubes also find uses in heavy equipment manufacturing such as cranes and garbage trucks.

precision seamless tubes 2 - Knowledges of seamless steel pipes

Due to the characteristics of high-precision, in precision machinery manufacturing, auto parts, hydraulic cylinders, construction (steel sleeve) industry has a very wide range of applications.

General process of cold drawing

A considerable proportion of the seamless tubes and pipes manufactured through the cold roll piercing technology undergo subsequent cold forming. The principal reasons behind cold drawing are:

precision seamless tubes 3 - Knowledges of seamless steel pipes
  • Achievement of closer wall thickness and diameter tolerance
  • Improvement in surface finish
  • To enhance serviceability
  • No premature failure
  • Suitable for critical forming Such as 180˚ Bends
  • Enhancement of mechanical properties of the tube
  • Expansion of product mix towards the lower end of the OD and wall thickness scales.


  • Hollow drawing
  • Stationery drawing or floating plug drawing and
  • Drawing over a mandrel (also known as drawing on-the-bar)

After the goods are cold drawn to sizes, the tubes are put on annealing furnace for heat treatment and normalising.


Post annealing, the goods are passed through a seven roller straightening machine to achieve proper straightening of the tubes.

Eddy current

Post straightening, each tube is passed through eddy current machine to detect for surface cracks and other defects . Only the tubes that pass eddy current are fit for delivery to customers.


Each tube is either oiled with corrosion resistant oil or varnished for surface protection and corrosion resistant as per customers requirement, each tube end is covered by plastic end caps to avoid damage in transit, the marking and specs are put and the goods are ready for dispatch.

Condition on delivery:
Term Symbol Explanation
(cold-finished as-drawn)
BK No heat treatment after the last cold-forming process. The tubes therefore have only low deformability.
(lightly cold-worked)
BKW After the last heat treatment there is a light finishing pass (cold drawing) With proper subsequent processing, the tube can be cold-formed (e.g. bent, expanded) within certain limits.
Annealed GBK After the final cold-forming process the tubes are annealed in a controlled atmosphere or under vacuum.
Normalized NBK The tubes are annealed above the upper transformation point in a controlled atmosphere or under vacuum.

Difference between galvanized steel pipe and seamless steel pipe

Galvanized pipe is protected by zinc, so it is not easy to rust, galvanized steel pipe is lighter than seamless steel pipe, if it is used in the balcony, the best light with galvanized pipe, because seamless steel pipe is heavy with thick wall thickness, and the cost of seamless steel pipe is higher than galvanized steel pipe, as well as galvanized steel is durable, useful life is much more than a seamless pipe. If the quality is excellent, using twenty years should not be an issue.

Surface coated or hot dip galvanized welded steel pipe can enhance corrosion resistance and prolong life.

Manufacturing process difference: galvanized steel refer to a galvanized surface, there may be welded pipe, it could be seamless, seamless steel pipe manufacturing process means welded and seamless points.

Seamless pipes are extensively applied for the nuclear device, gas, petrochemical, ship building and boiler industries. seamless pipes dominates 65% of market share in Chinese boiler industry.

Uses difference:

Seamless steel pipe is very widely used, except for water, gas, oil, general low pressure fluid line pipe, also used as heating oil oil industry in particular, marine oil field oil well pipes, pipelines, chemical coking equipment, a condensate cooler, coal distillation of wash oil exchange Used pipe, and trestle piles, mine tunnel support frame with a pipe. Galvanized pipe generally is utilized to make make fences, fence, fence, balcony guardrail. Commonly used in municipal projects, roads, factories, schools, development zones, gardens, squares, residential and other places.

How to packing the steel pipes

There are probably hundreds of different methods for packing a pipe, and most of them have merit, but there are two principles that are vital for any method to work prevent rusting and Sea transportation security.

steel strips bunding for fixed pipes - Knowledges of seamless steel pipes

  • Plastic caps plugged at the two sides of pipe ends
  • Should be avoided by the steel strapping and transport damage
  • Bundled signs should be uniform and consistent
  • The same bundle(batch) of steel pipe should be came from the same furnace.
  • The steel pipe has the same furnace number, the same steel grade, the same specifications.

Our packing can meet any needs of the customers.

bundle packing seamless pipe - Knowledges of seamless steel pipes
Bundle packing
naked packing seamless pipe - Knowledges of seamless steel pipes
Naked packing
crate packing seamless pipe - Knowledges of seamless steel pipes
Crate packing ASTM A213 T5b
protect by wood at both ends - Knowledges of seamless steel pipes
Protect by wood at both ends
packing u bend tubes - Knowledges of seamless steel pipes
Packing the U-bend tubes
packing oil pipes - Knowledges of seamless steel pipes

Protect by the pipe-caps

stainless tube packing4 little - Knowledges of seamless steel pipes

Stainless packing

Stainless Steel Seamless Pipes packing

Stainless Pipes are made from more than 20 steel grades of various corrosion resistance and are intended for application in conditions of a wide range of corrosion environments and temperatures in heat exchanger.

Source: Network Arrangement – China Seamless Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (

(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, 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.)

If you want to have more information about the article or you want to share your opinion with us, contact us at [email protected]

Please notice that you might be interested in the other technical articles we’ve published:

  • How to get high quality stainless steel pipes

  • What is the difference between a steel pipe and a steel tube

  • Engineering Specification for Pressure Test of Piping System

  • How To Distinguish Inferior Steel Pipe

  • How to get high quality steel pipes

  • Manufacturing process of cold rolled steel pipe

  • How to get high quality boiler tubes

  • How to get high quality flanges

  • How to get high quality alloy steel pipes

  • How to get high quality pipe fittings

  • How to get high quality heat exchanger tubes

  • The difference between steel tubes and steel pipes


  • Difference between galvanized steel pipe and seamless steel pipe



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