Analysis of the causes of the wrong side of spiral steel pipe

Spiral steel pipe in the production process if the production process is unreasonable, machine parameter settings shall be deemed to occur deviation phenomenon, especially large diameter spiral steel pipe, which is often said the wrong side of the phenomenon.

After spiral steel pipe wrong side analysis of the causes produce the wrong side is very necessary, the following is a common cause of generating the wrong side.
1, strip steel camber is caused by the wrong side of the most important factors. In forming the spiral welded pipe, steel strip camber angle will constantly change shape, leading to changes in the weld gap, resulting in open seam, wrong side or even take sides.

2, strip head and tail butt welding weld reinforcement is large, when the over-molding, if not handled properly, likely to cause greater wrong side.

3, due to the poor is not trimming the strip head and tail shape and size precision, easy to cause docking strip hard bend caused by the wrong side.

4, the strip edges in poor condition is another important reason for the wrong side.
Therefore, the observation strip coil-camber situations after, by controlling the vertical rolls so that the disc can be cut and removal of part of camber angle forming the continuous control and corrective camber of the strip is the reduction in the production process effective way of generating the wrong side.

For the production of spiral steel pipe processing program has been completed on the wrong side as follows:

1, the position of the wrong side of the polished, then welding
2, if a situation occurs frequently on the wrong side, you can replace the equipment.

Source: Zhejiang Yaang Pipe Industry Co., Limited (

Production process of spiral steel pipe

Spiral steel pipe is a strip coil as raw material, often warm extrusion molding, automatic double wire-sided submerged arc welding process welded spiral seam steel pipe main production processes are as follows:

 Production process of spiral pipe

Production process of spiral steel pipe

1. unwinding board probe: After entering the unwinding plate production line, the first full-board ultrasonic testing.
2. Leveling Milling: The flat steel anvil machine so that the original curl, and then through the edge milling machine for two-sided steel milling, so as to meet the requirements of the plate width, plate edge parallelism and groove shape.
3. shear molding: the steel plate production line along the outer edge of the spiral curl into a tube.
4. butt cut: double-sided submerged arc welding using advanced technology to pre-welding, internal welding, outside welding. Ion foot cut to specification length welded spiral pipe use and so on.
5. visual inspection: by professional and technical personnel to some of the basic parameters to be checked.
6. The ultrasonic flaw detection: internal and external weld and weld on both sides of the base material 100% inspection.
7. X-ray detection: internal and external welds 100% X-ray industrial TV check image processing system to ensure that the use of detection sensitivity.
8. The pressure test: the spiral steel pipe hydrostatic testing machine-by-root test to ensure that the pressure test pipe meet the required standards.
9. chamfering flat head: spiral steel pipe inspection carried out after the pipe end processing, to meet the requirements of the pipe end beveling size
10. Final inspection: ultrasonic and X-ray detection again and spiral steel pipe ends magnetic particle inspection, check if there are problems and welding pipe ends defects.
11. oiled marking: spiral steel pipe after passing were oiled to prevent corrosion, and according to user requirements for marking.
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Stainless steel rectangular pipe

Stainless steel rectangle pipe is a hollow strip steel pipe, a large number of used for conveying fluid pipe, such as oil, natural gas, water, gas, steam, etc., in addition, doing bending and torsional strength phase at the same time, the weight is lighter, it is widely used in the manufacture of machinery parts and engineering structures. Also commonly used for the production of various kinds of conventional weapons, barrel, shells, etc.

The classification of the stainless steel pipe:

Stainless steel pipe is divided into seamless stainless steel pipe and welded stainless steel pipe the two broad categories.

According to the cross section shape and can be divided into the stainless steel pipe and stainless steel special-shaped pipe, widely used is stainless steel pipe, square, rectangle, semicircle, but there are also some hexagonal, equilateral triangle, octagonal stainless steel special-shaped pipe, etc.

For fluid under pressure stainless steel pipes are hydraulic experiment was carried out to test the compression ability and the quality, under the pressure of regulation does not leak, soaked or expansion of qualified, some stainless steel pipe according to the standard or the buyer requires edge test, flaring test, flattening test, etc.

Stainless steel rectangular pipe, is made from solid pipe ingot or the perforation capillary, then through hot rolling and cold rolling or cold dial.

Stainless steel rectangular pipe specifications: 5 * 5 ~ 150 * 150 mm thickness: 0.4 ~ 6.0 mm

Rectangular pipe material: 304, 304, TP304, TP316L, 316 l, 316 l, 316 ti, 321, 347 h and 310 s
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What is the high temperature alloy?

What is the high temperature alloy?

High temperature alloy is also called hot strong alloy, super alloy. The materials can be divided into three groups: iron, nickel and chromium. According to the production method can be divided into the deformation of high temperature alloy and cast high temperature alloy

Classification according to the matrix elements, high temperature alloy is divided into iron, nickel base, cobalt base and other high temperature alloy.
Scope of application: General for aero engine manufacture of resisting high temperature materials, especially jet engine last two stage compressor and first two stage turbine blades, a combustion chamber, afterburners, manufacture of turbine disc, turbine blades and fasteners. Is an important strategic material, the aviation powers are under the condition of extremely confidential.
Advantages: high temperature alloy should has high creep strength and creep rupture strength (see creep), good thermal fatigue and mechanical fatigue properties (see fatigue), good resistance to oxidation and corrosion resistance of gas and stable organization, which the creep strength and creep rupture strength is most important.
The properties of high temperature alloy are closely related to the microstructure of the alloy, and the microstructure is controlled by the heat treatment of the metal. High temperature alloy is generally required after heat treatment. Solution treatment and aging treatment of precipitation strengthened alloy.
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The advantages of duplex steel

The advantages of duplex steel mainly have the following points:
(1) with good corrosion resistance, its wear resistance and corrosion resistance are better than that of austenitic stainless steel.
(2) enough plastic toughness needed for forming. The use of duplex stainless steel production tank or pressure vessel wall thickness, is conducive to reduce costs. Has excellent resistance to stress corrosion cracking ability, even the lowest duplex stainless steel alloys containing higher resistance should be the ability of stress corrosion cracking, especially in chlorine ion in the environment. In Xu
(3) the elongation rate of ferrite phase of the duplex steel is smaller than that of the austenitic phase, so the bending radius of the 2205 phase is larger than that of the austenitic stainless steel.
(4) the linear expansion coefficient is low, and the carbon steel is close to, which is suitable for the connection of carbon steel, and has important engineering significance, such as the production of composite plate or lining.
(5) under the condition of dynamic or static load, there is a higher energy absorption capacity, which is to deal with unexpected accidents such as collision, explosion, etc., the advantages of duplex stainless steel is obvious, it has practical application value.
(6) external anticorrosive coating repair system refers to the tube Daowai anticorrosion layer construction caused by local damage and handling and other factors caused by the damage of modifications, including pipe joint outer anti-corrosion layer construction and damage of repair.
(7) duplex steel is allowed to be used in the ASME boiler and pressure vessel code at temperatures below 316. The strength can be obtained through the ASME boiler and pressure vessel.
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Production method of stainless steel seamless pipe

Stainless steel seamless pipe according to the different production methods can be divided into hot rolling, cold rolling tube, cold drawn tubes, extruded tube, etc.
1, hot-rolled seamless steel pipe in automatic rolling on production unit. Solid billet through inspection and clear the surface defects, cut into the required length, centering on the tube billet perforation end face, and then sent to a heating furnace, punched on the punch. In perforated revolve and progress at the same time, under the action of roll and head, tube billet internal cavity formed gradually, according to the capillary. Then sent to automatically continue rolling mill. Finally approved by reeling mill all the whole wall thickness, the sizing sizing machine, to meet the specification requirements. Hot rolled seamless steel pipe production by continuous rolling pipe unit is a more advanced method.
2, if you would get a smaller size and better quality seamless steel pipe, must adopt the method of cold rolling, cold drawing or both combined. Cold rolling is usually conducted on two-high rolling mill, steel pipe in variable cross section round hole groove and motionless conical head of rolling in the annular groove. Cold drawing usually in 0.5 ~ 100 t single or double chain chain cold drawing machine.
3, extrusion method, the heating tube billet in airtight extrusion cylinder, perforated rods and extrusion, extrusion from smaller extrusion die. This method can produce smaller diameter of seamless steel pipe.
Source: Zhejiang Yaang Pipe Industry Co., Limited (

Process for pickling and passivation of stainless steel pipe fittings

Stainless steel pipe fittings for pickling passivation operation steps:
1. The preparation work
2. Chemical degreasing
1) chemical degreasing adopts groove soaking method, in addition to tank made of steel plate, the lining of PVC or PE.
2) use 12 ~ 15% (by volume) of nitric acid chemical degreasing treatment, temperature of 40 ℃ ~ 60 ℃, time is 2 ~ 4 hours.
3) stainless steel pipe fittings soak in the tank, should pay attention to the location of the place, avoid tube saved the air.
4) in the process of soaking should move up and down or the turning of stainless steel pipe fittings, the lumen solution change constantly, in order to improve the effect. When it is necessary to take out the stainless steel pipe fittings, soaked in water flushing after.
5) chemical degreasing and stainless steel pipe surface wetting by water completely.
3. Hot water rinse
1) after oil removal of stainless steel pipe fittings are taken from the in addition to the oil tank, soaked in 40 ℃ ~ 60 ℃ hot water tank inside the rinse, 5 ~ 20 minutes.
2) hot water tank made of steel plate, the lining of PVC or PE.
3) the content of chloride ion in water is less than 25 PPM.
4. Rinse with water
1) water rinse the stainless steel pipe fittings (0.1 Mpa pressure P P) with pressure water to wash.
2) the content of chloride ion in water is less than 25 PPM.
5. Passivation
1) passivation using slot in the pool.
2) passivation channel steel plate production, spread acid plastic lining.
3) soaking groove, attention should be paid to the location of the placement, avoid tube saved the air.
4) in the process of soaking should move up and down or the turning of stainless steel pipe fittings, the lumen solution change constantly, in order to improve the effect. When it is necessary to take out the stainless steel pipe fittings, soaked in water flushing after.
6. Dry
After passivation of stainless steel pipe fittings, to grasp with clean compressed air or nitrogen blow dry, and must have enough time (at least 2 hours) in natural passivation in the air.
7. Inspection
Should be done after passivation of stainless steel pipe fittings, self-inspection, mutual inspection, acceptance and then submit qc inspectors as required.
8. To protect
1) outside need to paint the surface of the pipe fittings, such as is carried out in accordance with the coating requirements.
2) after the inspection of stainless steel pipe with plastic plug seal, in three fabric bandage to protect, and identified.
Source: Zhejiang Yaang Pipe Industry Co., Limited (

The application of the stainless steel welded pipe in the oil refining industry

Oil refining device of stainless steel welded pipe, generally exist in the process of using the following questions:

(1) the stress corrosion cracking, transgranular fracture (mainly chloride), intergranular stress corrosion cracking (mainly sulfide).

(2) the pitting corrosion, intergranular corrosion,

(3) the naphthenic acid corrosion, mouth

(4) the carburizing embrittlement.

Corrosive factors mostly in oil refining crude oil into the together, the main for organic sulphur compounds (crude oil contains 0.01 5%) and inorganic salts (a few parts per million – 200 parts per million (PPM). Heating when they break down, may produce active substances, such as H2S and hydrochloric acid in the crude oil also contain so-called naphthenic acid organic acid, are too many content will cause the material corrosion, in addition to the crude oil into the corrosion factors, in order to improve the effect of refining, in addition to water, hydrogen, also using sulfuric acid and caustic alkali, ammonia, etc.
Therefore, according to the different corrosion of oil refining device with different materials. Such as high temperature sulfur system considering Al and Cr sulfur corrosion resistance and high temperature strength, use the Cr5 – Mo above materials; High temperature H2S – H2 system using 13 cr – Al, 18-8 ni steel; Cr – Mo steel is used in the high temperature and high pressure H2 system or surfacing 18 Cr – ni – Nb steel; Low-temperature H2S – H2O system chooses 00 cr18ni10, 00 cr17ni14mo2 or monel alloy lining, H2S – HCl – H2O system selects more than 00 cr18ni5mo3si pitting corrosion resistance, resistance to stress corrosion of stainless steel welded pipe; Naphthenic acid system, chooses 00 cr17ni14mo2 can low velocity case, high velocity it needs further research; Low temperature CO2 corrosion system, generally at about 200 ℃ can use 00 cr18ni10; Response H2 equipment modification in the furnace tube, high temperature heating furnace of steel tube and various fluid of hanger, stents can choose 25 cr – ni, 20 Incone alloy 800, etc.
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The application of stainless steel welded pipe in seawater desalination device

For seawater desalination technology, energy conservation and the development of practical method is to use an evaporative enrichment equipment – VVCC (that is, the vacuum and evaporation, condensation, aggregation). The device adopts the heat pump, stainless steel welded pipe can use evaporation and transform it into heat energy supply system, so as to realize the energy conservation. And if cooperate with various technologies from concentrate recovery of valuable materials, and coagulation shrink as the pure water available. Such a system is indispensable to circular society, and stainless steel in every part of the device has played an important role.
Cr formation of passive film of stainless steel welded pipe for nitric acid (HN03) show a significant that oxidizing acid corrosion resistance, but the sulfuric acid (- H2SO4) and hydrochloric acid (HC1) that non oxidizing acid, its poor corrosion resistance. So the joining of 8% or more Ni to improve on non oxidizing acid corrosion resistance. Stainless steel welded pipe can also adapt to outdoor and damp environment, processing is suitable for the production of various liquid concentration plant.
Stainless steel have been used in the standard concentration device, used in the evaporation tank, the pipe, heat pump and other stainless steel material to occupy more than half. Required features, the first is to maximize its corrosion resistance, stainless steel welded pipe, especially the pipe, heat pump, such as corrosion, will cause a sharp negative impacts. Therefore, choose carefully before the material to the practical solution corrosion test is necessary.
SUS304 steel should be used in general, the evaporation tank, while the pipe using SUS316L steel.
In short, the use of the heat-pump principle VVCC evaporation concentration device, can greatly reduce the flow of the seawater desalination cost. Stainless steel welded pipe using the steam enrichment process, but also can significantly reduce CO2 emissions. In this, has played an important role in the use of stainless steel.
Source: Zhejiang Yaang Pipe Industry Co., Limited (

Selection of five factors to consider stainless steel pipe

When selecting stainless steel welded pipe in the corrosive environment, in addition to deal with the working conditions of stainless steel welded pipe has a detailed understanding, also need to consider the main factors are: stainless steel welded pipe corrosion resistance, and strength, toughness and physical properties, processing, formability, resources, price and obtain easily.
1. The corrosion resistance of the standard is for sure, both to admit it, use it, and cannot be bound by it, according to the specific requirements to determine whether the specific standard of corrosion.
On the corrosion resistance of stainless steel welded pipe is used more 10 standard, choose which level as the requirement of corrosion resistance, want to consider equipment, part a (its thickness, size). The characteristics of using lifespan, product quality (such as impurities, color, purity) and so on request, generally speaking, in the process of using smooth mirror or size precision instrument equipment and components, can choose 1 ~ 3 grade standard; Work closely with the requirements.
2. The corrosion resistance is relative and conditional, often say stainless of stainless steel welded pipe, the corrosion resistance of point relative to the rust and corrosion resistant, is refers to under certain conditions (medium, concentration, temperature, impurities, pressure, flow velocity, etc) must be. So far, has not been in any corrosive environment are not rust resistance, corrosion resistance of stainless steel welded pipe, so option material researchers must according to the specific conditions of use to choose, stainless steel welded pipe type is selected, use the department have to choose the correct use of the characteristics of the stainless steel welded pipe is reasonable material selection and correct use of to achieve has the objective of does not rust or corrosion.
3. Choose the stainless steel welded pipe should not only consider the general corrosion resistance, also want to consider the performance of its resistance to local corrosion, and in some water chemical medium, which need more attention, this is because, typically more material attaches great importance to the general corrosion resistance of stainless steel welded pipe, and under the conditions of use, they are for local corrosion, such as sensitivity to the stress corrosion pitting corrosion and so on how to consider less; Stainless steel welded pipe more than in the general corrosion resistance good local corrosion occurred in corrosion environment, local corrosion often result in stainless steel welded pipe equipment, the sudden destruction of parts, the harm is far greater than the general corrosion. 4. The application of various kinds of manual data on the corrosion resistance of stainless steel welded pipe.
4. Under the condition of some use, will also meet this kind of situation, when the work in the media or in the production of industrial products, some or even contained the metal ions in the stainless steel welded pipe, it will affect the quality of the chemical process industry industrial products (including the luster, color, purity, etc.). This kind of situation in the nuclear fuel pharmaceutical and dye industries are the most common, often choose at this time does not contain an element of stainless steel welded pipe or appropriate chooses stainless steel welded pipe corrosion resistance level, so that the reduced to allow the limits of metal ions.
5. Stainless steel welding control device, if parts failure due to corrosion, should carry out the analysis of the corrosion damage reason, find out the reason after take measures, and should not be a throw it.
Source: Zhejiang Yaang Pipe Industry Co., Limited (