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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.

2、Uncoiling

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.

10、Straightening

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.

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%.

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.

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 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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Introduction to 4142 alloy steel:
4142 steel is an ultra-high-strength steel with high strength and toughness, good hardenability, no obvious temper brittleness, high fatigue limit, multiple impact resistance after quenching and tempering, and good low-temperature impact toughness. This steel is suitable for manufacturing large and medium-sized plastic molds that require a certain strength and toughness. Usually, surface quenching after quenching and tempering is used as a heat treatment solution.

4142 alloy steel chemical composition:
Carbon C: 0.40～0.45%
Silicon Si: 0.15～0.35%
Manganese Mn: 0.75～1.00%
Sulfur S: ≤0.040%
Phosphorus P: ≤0.035%
Chromium Cr: 0.80～1.10%
Molybdenum Mo: 0.15～0.25%