Share a way to identify seamless steel pipe and welded pipe

Steel pipe appearance, seamless steel pipe, and welded steel pipe difference in the welded pipe inside the wall there are welding tendons, while the seamless no.
seamless steel pipe and welded pipe identification method: look at the inside of the tube, because the outside will be processed, welded pipe is a gap inside some can see, in some processing, it is not easy to see, you can slowly touch it with your hands, or look at the specifications, welded pipe are relatively thin, seamless steel pipe manufacturer, a welded pipe is made directly from stainless steel strip with a machine (rolled up), seamless is made from round steel or pipe billet perforated through.

Seamless steel pipe production principle

Production and manufacturing methods can be divided into hot-rolled tubes, cold-rolled tubes, cold-drawn tubes, extruded tubes, etc. according to different production methods. Hot-rolled seamless pipes are generally produced on automatic pipe-rolling units. Solid billets are inspected and cleared of surface defects, cut to the required length, centered on the perforated end face of the billet, then sent to a heating furnace for heating and perforated on a perforating machine. In the perforation, while continuously rotating and advancing, under the action of the rollers and the top, the internal cavity of the billet is gradually formed, called the hairpin. Then sent to the automatic tube rolling machine to continue rolling. The wall thickness is evenly adjusted by the equalizing machine, and the diameter is sized by the sizing machine to meet the specifications.

straight seam welded steel pipe

Embroidery removal method for straight seam steel pipe

In the process of anti-corrosion construction of oil and gas pipelines, the surface treatment of straight seam steel pipes is one of the key factors determining the service life of pipeline anticorrosion, and it is the premise of whether the anticorrosion layer can be firmly combined with straight seam steel pipes. According to the research of professional institutions, the life of the anti-corrosion layer depends on factors such as coating type, coating quality, and construction environment, and the surface treatment of straight seam steel pipes has an impact on the life of the anti-corrosion layer. According to the requirements of the layer specification for the surface of straight seam steel pipes, continuously improve the surface treatment methods of straight seam steel pipes,

There are mainly the following methods for removing embroidery from straight-seam steel pipes:

1. Cleaning Use solvents and emulsions to clean the steel surface to remove oil, grease, dust, lubricants, and similar organic matter, but it cannot remove rust, scale, welding flux, etc. on the steel surface, so it is only used in defense operations. Auxiliary means.

2. Pickling Generally, chemical and electrolytic pickling are used for pickling treatment. Only chemical pickling is used for pipeline anticorrosion, which can remove scale, rust, and old coatings. Sometimes it can be used as retreatment after sandblasting and rust removal. Although chemical cleaning can achieve a certain degree of cleanliness and roughness on the surface, its anchor pattern is shallow and it is easy to cause pollution to the surrounding environment.

3. Tool rust removal Mainly use tools such as wire brushes to polish the steel surface, which can remove loose scale, rust, welding slag, etc. Hand tool derusting can reach the Sa2 level, and power tool derusting can reach the Sa3 level. If the iron oxide scale is firmly attached to the surface of the steel, the de-rusting effect of the tool is not ideal, and the anchor pattern depth required for anti-corrosion construction cannot be reached.

4. Spray de-rusting Spray de-rusting uses a high-power motor to drive the spray blades to rotate at high speed, so that steel shots, steel sand, iron wire segments, minerals, and other abrasives are sprayed on the surface of straight seam steel pipes under the powerful centrifugal force of the motor, not only Oxide, rust, and dirt can be completely removed, and the straight seam steel pipe can achieve the required uniform roughness under the action of violent impact and friction of abrasives.

After spray de-rusting, not only the physical adsorption on the surface of the pipe can be expanded, but also the mechanical adhesion between the anti-corrosion layer and the surface of the pipe can be enhanced. Therefore, spray rust removal is an ideal rust removal method for pipeline corrosion. Generally speaking, shot blasting is mainly used for the inner surface treatment of pipes, and shot blasting is mainly used for the outer surface treatment of straight-seam steel pipes. In the production process, the technical indicators related to rust removal should be strictly required to prevent secondary damage to the straight-seam steel pipe due to operational errors. Embroidery is a frequently used technique in the steel pipe industry.

316 stainless steel manufacturer

How is 316 stainless steel pipe produced?

316 stainless steel pipe has good corrosion resistance and high-temperature resistance and is commonly used in chemical, food, light industry, mechanical instrumentation, and other industrial transmission pipelines as well as mechanical structural components. Then you know how the 316 stainless steel pipe manufacturer is produced? The following will take you to understand one by one.

1、Selected material

The use of cold-rolled stainless steel strips as raw materials, the surface state BA grade. Before the steel strip is used in the factory, the strip must be inspected in detail. Inspection items include thickness, width, edge quality state, appearance, and physical properties inspection. If necessary, the grain size of the original material is to be inspected, the inspection can be used for production only after passing.


Before entering the welded pipe unit, the steel strip needs to be unrolled using the steel strip uncoiler, and the steel strip needs to be leveled by adding a leveling mechanism to ensure that the steel strip enters the forming part of the welded pipe unit in a straight state, so that the bending of the steel strip can be completed successfully.

3、Pipe billet forming

Continuous roll bending equipment is used to continuously roll bend the steel strip to make an open pipe billet. The steel strip needs to pass the introduction module, rough rolling module, closing module of the welded pipe unit several functional modules, each module uses different types of rolls to achieve the bending of different parts of the steel strip forming, and finally, the steel strip from the plane gradually bent to form an open billet, ready for welding into 304 stainless steel pipe.

4、Continuous welding

Steel strip after continuous roll forming unit, made of open pipe billet. Use TIG welding equipment, continuous welding, made of round tube. The welding process uses argon as a protective gas to prevent oxidation before the weld solidifies and cools in contact with oxygen. The argon gas is passed into the tube to protect the internal weld seam, and the argon gas passed into the torch is used to protect the tungsten electrode. Around the melt pool to form a protective layer of argon gas to protect the melt pool and the weld from oxidation.

5、Welding seam leveling

Due to the impact of welding current and gravity, resulting in the protrusion of the internal weld of stainless steel products tube, the external weld will also appear depressed, these problems will not have an impact if used in an ordinary low-pressure fluid environment. If used in high temperature, high pressure, and high-speed fluid environment, will cause problems in use. This defect must be eliminated by using special weld seam leveling equipment.

6、 Online heat treatment

Steel strips for the roll bending forming process will produce process hardening, which is not conducive to post-processing of the pipe, especially for the pipe bending process. During the welding process, there will be welding stress at the weld seam, which will cause cracking potential in the later use process, which requires heat treatment.

Currently commonly used heat treatment process for hydrogen protective atmosphere bright solution treatment, 304 stainless steel pipe heated to more than 1050 °, after a period of insulation, is the internal tissue morphology transformation, the formation of uniform austenite organization, under the protection of hydrogen atmosphere, no oxidation.

7、Sizing finishing

The outer diameter size of the welded pipe, in the welding and heat treatment process, will be deformed, resulting in the outer diameter size can not meet the requirements of use, and the need for sizing finishing. Usually used sizing and finishing unit consists of 4 sets of flat rollers and 4 sets of side rollers, flat rollers are designed as flat oval (or round), and side rollers are designed as oval (or round). The sizing amount is different according to the outer diameter and wall thickness of the tube, generally within the range of 0.20~0.50mm. After sizing and finishing, the outer diameter tolerance of the tube can be controlled within ±0.05mm, which can fully meet the accuracy requirements.

8、On-line flaw detection

Due to the pressure, and the need for a certain degree of reliability, the weld only relies on pressure detection is difficult to detect internal defects in the weld, you can use online eddy current flaw detection or ultrasonic flaw detection, real-time online 100% detection. The welding state can be corrected at any time according to the alarm information to reduce the production of substandard products.

9、Sizing cutting

Using online cut-to-length equipment, according to the length required by the customer, cut-to-length, you can use rotary cutting (chipless) technology, compared with chip cutting, chipless cutting has no cutting burr characteristics, at a later stage, you can not deburr the port.


Roll forming unit production of welded pipe straightness can not meet the requirements of the use of the general straightness of such welded pipe needs to be controlled at 0.10/100mm. need to use a straightening machine to straighten the welded pipe to achieve the required production requirements.

11、Pressure test

The use of an automatic static water pressure test machine, the 304 stainless steel pipe pressure test, loading, flushing, and pressure testing, under the material, all automatically complete, pressure after a certain period of time through the differential pressure method to sort out an unqualified welded pipe.
12、Cleaning and drying

Welded pipe in the completion of mechanical processing, the need for the final cleaning and drying, to remove the inner wall or outer wall of the pipe residual coolant, oil and other pollutants, and then use for hot air drying to prevent rust during transport and storage. Finally, the finished stainless steel welded pipe inspection and packaging, you can leave the factory.

The above is the production process of 316 stainless steel pipe, the production process includes the selection of materials, uncoiling, billet forming, continuous welding, welding seam finishing and a series of processes.

Titanium Alloy Thin-walled Workpieces

Difficulties and Cause Analysis of Processing Titanium Alloy Thin-walled Workpieces

In the machinery manufacturing industry, titanium alloy materials have characteristics that other metal materials cannot possess: high specific strength, high heat strength, and good corrosion resistance; the alloy density is only 58% of steel, so thin Wall and shell structural parts will become common workpieces for defense products. Due to the thin wall of the workpiece, it is easy to deform during processing. The radial clamping force causes elastic deformation of the workpiece, and the tool wears quickly to make the processing size unstable. It is difficult to guarantee the processing quality, which makes the workpiece reject rate and processing cost high. Technicians and processing operators.

The traditional processing of titanium alloy thin-walled workpieces does not pay attention to the selection of tool materials and cutting elements, which makes the processing tools wear faster and the deformation increases; Improper design of the fixture used to eliminate clamping deformation; process measures that do not pay attention to dimensional stability after processing; the biggest bottleneck in the processing of thin-walled titanium alloy workpieces is difficult processing of materials, high requirements for dimensional accuracy and shape and position tolerance, thin wall and easy deformation , There are many factors that affect processing deformation, mainly reflected in the following aspects.

(1) The generation of cutting heat caused by the thin wall of the workpiece causes deformation

The thermal conductivity of titanium alloy materials is smaller than that of stainless steel and high-temperature alloys, and the difference in heat dissipation conditions is 1/4 and 1/16 of that of iron and aluminum, which makes the temperature in the cutting area rise rapidly, and it is difficult to disperse when it accumulates near the cutting edge, resulting in processing defects. Stress concentration near the tool tip causes tool wear and chipping, resulting in deformation of the workpiece.

(2) The rigidity of the workpiece is poor. During the cutting process, the vibration of the machine tool and improper cutting elements will cause deformation. The rigidity of the thin-walled workpiece is poor. When processing thin-walled titanium alloy workpieces due to factors such as machine tool vibration, the inappropriate cutting speed will cause vibration during the cutting process. , causing deformation.

(3) The radial clamping force produces deformation during the cutting process of the workpiece

When processing and clamping titanium alloy thin-walled workpieces, under the action of radial clamping force, it is easy to cause elastic deformation, which affects the dimensional accuracy and shape tolerance requirements of the workpiece.

(4) Deformation due to stress release during workpiece cutting

During the processing of titanium alloy thin-walled workpieces, the stress will be released every time the metal is cut, causing deformation of the workpiece.

Incoloy 800

The main difference between Incoloy800, 800H, 800HT

Alloy 800 (UNS N08800), 800H (UNS N08810), 800HT (UNS N08811) is a solid solution high strength austenitic nickel-iron-chromium alloy. Nichrome is designed for resistance to oxidation and carbonization at elevated temperatures, high temperature oxidation resistance, high temperature scaling resistance and high temperature carbonization resistance. Excellent overall corrosion resistance. When the nickel content is 32%, the alloy’s resistance to corrosion cracking caused by chlorides and to embrittlement in the process of precipitation in sigma state can be enhanced. At the same time, it also has excellent resistance to uniform corrosion, and has excellent corrosion resistance in extremely high-temperature water media at 500°C. The service temperature of alloy 800 is about 590°C, and the service temperature of alloy 800H/800HT is above 590°C, which has excellent creep resistance and crack resistance. In terms of mechanical properties, it has excellent mechanical properties no matter at zero temperature, room temperature or high temperature of 600°C. Its excellent cold forming performance makes this alloy widely used in the manufacture of bellows, expansion joints and other equipment. These three Type 800 series alloy products have been widely used in ASME boilers, booster valves, first sections of electric boilers, third sections of nuclear material containers and red high pressure vessels.

Alloys 800, 800H, and 800HT are high-strength austenitic nickel-iron-chromium alloys in solid solution. Nickel-chromium-iron alloy is designed for anti-oxidation and carbonization when the temperature rises. It is resistant to high-temperature oxidation, high-temperature peeling and high-temperature carbonization, and has excellent overall corrosion resistance. These three 800 series alloy products have been widely used in ASME boilers, booster valves, the first section of electric boilers, the third section of nuclear material containers and red high pressure vessels, etc.

But what is the difference between them? Let’s describe it with data from the aspects of chemical properties and physical properties.

The grade corresponding to 1.800 is UNSN08800,

The grade corresponding to 800H is UNS N08810,

The grade corresponding to 800HT is UNS N08811;

2. In terms of chemical composition, there are some differences in the content of C, and the other requirements are the same:

C≤0.10 in 800,

0.05≤C≤0.10 in 800H,

0.06≤C≤0.10 in 800HT;

3. In terms of physical properties,

800 requires tensile strength ≥ 517MPa, yield strength ≥ 207MPa, elongation ≥ 30%;

Like 800HT, 800H requires tensile strength ≥448MPa, yield strength ≥172MPa, and elongation ≥30%.

the price range of Hastelloy 625

What is the price range of Hastelloy 625?

According to the number of constituent elements, alloys can be divided into binary alloys, ternary alloys, and multi-element alloys. Common alloys are aluminum alloy, steel, titanium, etc. The price of Hastelloy 625 gold is 350 yuan per kilogram, the price is low, and the support is free to deliver to the door. It has good resistance to reduction and mild oxidation corrosion. Excellent resistance to stress corrosion cracking. Very good resistance to localized corrosion. A corrosion-resistant alloy with many excellent properties. It has good resistance to oxidation and moderate reduction corrosion.

Alloy concepts and properties

Alloy: A substance that is formed by fusing two or more metals or metals and nonmetals, and has metallic properties.

①The alloy must contain metal elements

②Alloys may also contain non-metallic elements;

③Most alloys are mixtures;

④ Each component in the alloy still maintains its chemical properties;

⑤ Formed by fusion conditions.

Alloy properties

In general, alloys are compared to their pure metal constituents

(1) The hardness is greater than that of any component metal.

Such as aluminum alloy is harder than pure aluminum, and iron alloy is harder than pure iron

(2) The melting point is lower than that of any constituent metal.

Such as the melting point of fuse and pig iron is lower than that of pure iron

(3) Often have excellent physical, chemical, or mechanical properties.

(4) The electrical and thermal conductivity is lower than that of any component metal.


Properties of Incoloy800H (N08810) nickel-based alloy

ncoloy800H is resistant to corrosion by many corrosive media. Its high nickel content gives it good resistance to stress corrosion cracking in aqueous corrosion conditions. The high chromium content gives it better resistance to pitting and crevice corrosion cracking. The alloy has good corrosion resistance to nitric acid and organic acid but has limited corrosion resistance to sulfuric acid and hydrochloric acid. In addition to the possibility of pitting corrosion in halides, it has good corrosion resistance in oxidizing and non-oxidizing salts. It also has good corrosion resistance in water, steam, and mixtures of steam, air, and carbon dioxide.

Incoloy800H high-carbon type has a carbon content between 0.05 and 0.10. It is mainly used for temperatures above 600 degrees. It has the characteristics of coarse grains, high creep strength, good mechanical properties, and corrosion resistance. It is used in the chemical industry, Power, superheater, reheater, high-temperature heating, conversion cracking furnace tube, etc. in the petrochemical industry.

Incoloy800H processing and welding: thermal processing performance is good, the thermal processing temperature is 900~1200, and hot bending forming is at 1000~1150 degrees, in order to reduce the intergranular corrosion tendency of the alloy, it should pass through the sensitization zone of 540~760 degrees as quickly as possible. Intermediate softening annealing is required during cold working. The heat treatment temperature is 920~980. The solution temperature is 1150~1205. The welding performance is good, and the conventional welding method is used.

Incoloy800H corresponding grade:

National standard: NS1102, NS112, 0Cr21Ni32AlTi, American standard: Incoloy800H, N08810, German standard: 1.4958, X5NiCrAlTi31-20

Incoloy800H corrosion resistance: the alloy has good corrosion resistance to nitric acid, organic acid, oxidizing, and non-oxidizing salts except halogen salts. Especially high-temperature corrosion resistance, has good carburization resistance, intergranular corrosion will occur when the alloy is heated between 593~816 and has good stress corrosion resistance, but long-term aging at 650 degrees may significantly reduce the stress corrosion sensitivity of the alloy, In NaOH, NACL stress resistance depends on concentration and level. It has good resistance to stress corrosion cracking and has resistance to stress corrosion cracking in hydrochloride, corrosion resistance to steam, air, and carbon dioxide mixture, and good corrosion resistance to organic acids such as nitric acid, formic acid, acetic acid, propionic acid, etc., but After heating, it will cause sensitization and intergranular corrosion. It can only resist the low concentration of sulfur and hydrochloric acid corrosion. It has good corrosion resistance to organic acids and good corrosion resistance to flowing seawater, but deposits will form on the surface of stagnant seawater. And cause severe corrosion cracks.

Incoloy800H application fields: superheater, reheater, high-temperature heating, conversion cracking furnace tube, etc. in the chemical industry, electric power, and petrochemical industry.

17-7PH (SUS631)

17-7PH (SUS631) precipitation hardening stainless steel strip hardness

17-7PH precipitation hardening stainless steel is a kind of martensitic steel with good strength and processing performance. The overall performance of the alloy becomes better after heat treatment. The composition complies with the GB/T1220-2007 standard and can be used for parts such as springs. . 17-7PH contains a high content of chromium, up to 17%, and has good corrosion resistance. It takes a slant to add aluminum alloy elements to the alloy to enhance the strength of the material.

17-7PH chemical composition:

Carbon C:≤0.09

Silicon Si:≤1.0

Manganese Mn:≤1.0

Sulfur S:≤0.03

Phosphorus P:≤0.04

Chromium Cr: 16.0~18.0

Nickel Ni:6.50~7.75

Aluminum Al:0.75~1.50

The Cyclone Global Navigation Satellite System spacecraft

Hurricane-tracking satellites can also keep tabs on harmful microplastics in the ocean

The Cyclone Global Navigation Satellite System spacecraft

The Cyclone Global Navigation Satellite System spacecraft were designed to track hurricanes but they can also monitor microplastics in the oceans. (Image credit: NASA)

A satellite system designed to track hurricanes can reveal where damaging microplastics accumulate in the ocean. A new study now reveals why.

In 2021, researchers from the University of Michigan and Southwest Research Institute found that spacecraft from the Cyclone Global Navigation Satellite System can distinguish areas in the ocean with higher concentrations of microplastics.

From their orbit some 333 miles (536 kilometers) above Earth, these satellites are able to see odd patches in the ocean with smaller and fewer waves, which were found to be areas with high concentrations of microplastics on the surface. In the new study, the researchers have now revealed what exactly is happening in the microplastic-laden water, and they hope the results will make this new satellite monitoring method more reliable.

Microplastics are a huge environmental problem. Less than 5 millimeters across, these minuscule fragments of plastic waste are polluting the entire planet, including the bodies of humans and animals on all continents and in the oceans. Microplastics have been found in drinking water as well as in the food we eat. In the world’s oceans, microplastics are particularly harmful. According to the University of Plymouth(opens in new tab) in the U.K., there are trillions of microplastic particles polluting the marine environments and they are being swallowed up by all kinds of marine creatures from the tiniest plankton to giant whales. These tiny pieces of rubbish are particularly hard to clean up due to their small size, and up until recently were also hard to track, as scientists had to rely on patchy eye-witness accounts.

The new satellite tracking method could improve microplastic monitoring, which in turn could make clean-up efforts easier.

In the new study, researchers from the University of Michigan wanted to test why exactly it is that water thickly polluted with microplastics forms smaller waves. They experimented in a laboratory, creating artificial waves in a small pool. They found that the reason for this reduced wave size in the polluted water is not due to the microplastics alone, and instead is also caused by the presence of surfactants, oily chemicals that these plastics are frequently infused with to alter their properties.

Researchers tested about water

Researchers tested how microplastics affect the ability of water to form waves. (Image credit: Robert Coelius, Michigan Engineering)

“We can see the relationship between surface roughness and the presence of microplastics and surfactants,” Yulin Pan, a naval architecture and marine engineering assistant professor at the University of Michigan and corresponding author on the paper, said in a statement(opens in new tab). “The goal now is to understand the precise relationship between the three variables.”

The researchers want to develop a model that would allow them to not only monitor microplastics from space but also to predict the motion of plastic-polluted water in the ocean.

The study(opens in new tab) was published on Feb. 8 in the journal Scientific Reports.

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welding alloy 600

Chromium-nickel alloy 600 and its processing technology

Alloy 600 (UNSN0660) is an alloy with nickel as the main component and resistance to various corrosion conditions. Alloy 600 (UNSN0660) can be used in low-temperature and high-temperature environments of 20000F (10930C). It has no magnetism and can be welded for corrosion resistance. Its nickel alloy content is high, and it has strong corrosion resistance and good resistance to chloride stress corrosion cracking. Chromium makes it suitable for low oxidation environments.

General characteristics

Alloy 600 (UNS designated N0660) is a chrome-nickel alloy, which is designed for environments ranging from low temperatures to 2000 degrees Fahrenheit (1093 degrees Celsius). The alloy is non-magnetic and easy to weld. Alloy 600 is used in various anti-corrosion fields. Its high nickel content shows a certain degree of corrosion resistance in environments with reduced corrosion degree, while chromium in the alloy has corrosion resistance in a weak oxidation environment. The high nickel content in the alloy has special resistance to chloride corrosion fission.

Application field:

① Chemical and food processing equipment

② Paper mill and alkali digester

③ Heat exchanger

④ Heat treatment silencer and evaporator.

Heat treatment:

Alloy 600 will not harden during heat treatment. The hardness of the alloy can only be enhanced by cold treatment. After cold working, the alloy is annealed to soften the material. Softening needs to be carried out from the initial temperature of 1600 degrees Fahrenheit (871 degrees Celsius) to 2100 degrees Fahrenheit (1149 degrees Celsius). When the temperature rises to 1800 degrees Fahrenheit (982 degrees Celsius) or higher, the particles will grow rapidly. However, if the material is softened at 1900 degrees Fahrenheit (1038 degrees Celsius) in a very short time, the particles can be prevented from getting too large. Slow cooling and quenching can keep the hardness of alloy 600 approximately the same.


Alloy 600 exhibits good cold-forming properties, which is related to the Ni-Cr stainless steel it contains. Its high nickel content prevents its transformation from austenitic steel to martensitic steel, which will occur when 301 stainless steel alloy and 304 stainless steel alloy are cold formed. Compared with 301 alloy and 304 alloys, the effective hardening rate of 600 alloys is lower, and it can be used for rolling forming by various methods, but a large amount of deformation will occur between annealing and annealing.

If high*temperature annealing is used, alloy 600 produces relatively large particles to obtain the characteristics brought by the temperature rise, and the surface is formed in the maximum range to form obvious waviness, which is called “orange peel”. This phenomenon is caused by large particles, which are generally considered harmful to the material properties.


The standard resistance welding and fusion welding of stainless steel can be used for alloy 600. Electrodes and wires for welding alloy 600 and other materials can be found on the market. Because this alloy will produce oxides with strong adhesion, inert gas protection should be reasonably used.