DSAW Steel Pipe

DSAW steel pipe can be specified in very large diameter and to exact inside or outside dimensions. Spiral Welded steel pipe is distinguished by the manufacturing process that results in a spiral DSAW seam the length of the pipe to lengths of 155 feet. 

The manufacturing of Double Submerged Arc Welded Pipe involves first forming steel plates into cylindrical shapes. Then the edges of the rolled plate are formed so that V-shaped grooves are formed on the interior and exterior surfaces at the location of the seam. The pipe seam would then be welded by a single pass of an arc welder on the interior and exterior surfaces. The welding arc is submerged under flux. What can be known as an advantage of this process is that welds would penetrate 100% of the pipe wall and produce a very strong bond of the pipe.

Hunan Great Steel Pipe Co.,Ltd would like to supply all kinds of high quality carbon steel pipe for our customer

Contrast of Welded Steel Pipe

Conveying pipe by the different pipe process, can be divided into seamless steel tube (SML), mainly as oilfield gathering tube and small diameter internal high pressure natural gas pipeline, used for long distance oil and gas pipeline of few in number, the vast majority of long distance pipeline is to use high frequency straight seam welded pipe (ERW), spiral submerged arc welding pipe (SSAW), straight seam submerged arc welding pipe (LSAW steel pipe) three. The table below for the process features of several kinds of steel pipe and quality performance contrast:

High frequency straight seam welded pipe (ERW) according to the welding process is divided into different induction welding and resistance welding two forms, using hot rolled wide strip coil as raw material, through the continuous forming, bending, welding, heat treatment, sizing, straightening, cutting process, such as weld short compared with spiral welded pipe, high dimensional accuracy, uniform wall thickness, good surface quality, high pressure, etc. But the disadvantage is that only production of small diameter thin wall pipe, weld easy generation resistant, incomplete fusion, trench corrosion defects. Widely used such as city gas, crude oil transportation.

Spiral submerged arc welding pipe (SSAW) steel strip coil direction when the forming Angle with the center line of the pipe forming (adjustable), forming and welding, the welding seam into spiral, advantage is that the same specifications of the steel strip can produce various specifications of the steel tube diameter, raw material range is larger, the weld can avoid the principal stress, the stress condition is good, the disadvantage is that poor geometry size, weld length compared with straight seam length, easy to produce cracks, porosity, slag, weld defects such as welding, welding stress is tensile stress state. The rules and regulations of general oil and gas long distance pipeline design of spiral submerged arc welding pipe can only be used for 3, 4 regions. Abroad will improve after this process will be raw materials instead of steel plate, forming and welding, then welding and lean, cold expanding, after welding, the welding quality is close to UOE tube, at home there is no such process, is the direction of the mild steel pipe factory to improve in our country. "West-east gas" spiral tube is still used by traditional craft production, only the pipe hole enlargement. The United States, Japan and Germany, on the whole, negative SSAW, don't think it is proper to use SSAW trunk; Canada and Italy part use SSAW, Russia a small amount of use of SSAW, and have made a very strict complementary condition, due to historical reasons, most domestic trunk or use SSAW.

Introduction of LSAW Steel Pipe

Straight seam submerged arc welding pipe (LSAW steel pipe) based on single Zhang Zhonghou plate as raw material, the steel in the mold or molding machine medium-voltage (roll) into the pipe, using double-sided submerged arc welding and ChengJinHang production of hole enlargement. Its finished product specification range is wide, the toughness of the weld, plasticity, good uniformity and compactness, with large pipe diameter, wall thickness, strong resistance to high pressure, low temperature corrosion resistance, etc. In the construction of high strength, high toughness, high quality of long distance oil and gas pipeline, the steel tube are mostly straight seam submerged arc welding of large diameter thick wall pipe. According to the provisions of the API standard in large oil and gas pipelines, when the elevations, sea and city populated area in class 1, 2, straight seam submerged arc welding pipe is the only specify the applicable type. According to the forming methods of different can be divided into:

UOE welded steel pipe, sheet steel plate after edge bending, after U shape, O forming, welding, welding, mechanical cold expanding process;

JCOE welded pipe: according to "J - E - C - O" after welding, forming, welding process by cold hole enlargement, etc;

HME welded pipe: the mandrel rolling method according to the "C - C - O" after forming, welding process by cold hole diameter, etc.

Forming Situation effect the quality of the welded steel pipe

n high frequency straight seam welded steel pipe production, the tube billet forming joint condition directly affects the quality of the weld, during which the butt welding joint surface parallel degree is particularly important. In the process of steel tube joint welding, first through the adjustment quantity of the roller on the roller and the gap between the top roller to ensure that the parallel degree of joint. Welding of kneading roller pass characteristics of kneading rack up roller pass radius around 10% larger than other kneading roller, thus, kneading roller on the outside of the roll surface with steel tube aspirations of circular cross section, the gap between the gap is commonly known as "followed by the gap". In the actual forming, steel pipe section may be ambitious round. Usually, due to inadequate deformation of strip steel edge, section simple peach shape, if do not adjust it will constitute welding joint surface is not parallel to the docking, serious affect weld quality.

If the kneading roller and other kneading roller chooses the same radius of groove, when after adjusting the quantity of the kneading roller to eliminate the v-shaped joint, the outer edge of the roller roller surface will be strong pressure on the steel pipe appearance, simple tube surface scars, and pose a serious V joint. Set, thus "followed by the gap" is based on the actual characteristics of tube billet forming, after adjusting quantity of the roller to effectively eliminate V joint. Kneading roller on the way to adjust in accordance with the specifications set groove roller bearing, if discover forming joint is V, can be within the scope of the "followed by the gap", on the quantity of the kneading roller to adjust. On the limit of the quantity of the kneading roller is kneading roller outer roller surface on the mild steel pipe appearance constitute a shallow indentation. According to experience, when arrived at the pressure limit, even a high strength steel tubes, generally can also constitutes a forming joint parallel (I). In the use of the experience, must be strictly in accordance with the planning values to set the gap between the two on the roller. The gap change will directly lead to "followed by the gap". If each roll change when not strictly according to the planning value set, the gap then pass adjustment reproducibility is difficult to realize. For the same reason, in the asymmetric adjustment to eliminate roll on the right side, must only to adjust work station on the side of the roller, and let the other side of the top roller is fixed as the benchmark. If adjust both sides on the roller, may make the roll gap gradually away from the set point.

Standard of Piling Spiral steel pipe

Piling with spiral carbon steel pipe is hot rolled steel coil tube billet, often spiral shape, made of double-sided submerged arc welding or high frequency welding, used in civil construction, port, bridge pile foundation with steel pipe. So what requirements are required to piling with spiral steel pipe? Here give you a detailed analysis of spiral tube mill.

1, raw material is steel strip coil, wire, flux. Have to pass strict physical and chemical inspection before investment.

2, the head and tail docking strip, use single or double wire submerged arc welding, after rolled steel tube adopts automatic submerged arc welding repair welding.

3, have continuous acoustic detection of weld mark parts, after manual ultrasonic and X-ray check, if there are defects, after repair, again through the nondestructive inspection, until defects have been eliminated.

4, strip steel butt weld and fellowship with spiral weld d joint in the tube, all pass X-ray films and television inspection.

5, each welded steel pipe after hydrostatic pressure test, radial sealing for the pressure. Test pressure and time are controlled strictly by steel pipe hydraulic microcomputer testing device. The parameters automatically printed out.

6, after welding the weld passes the online continuous ultrasonic automatic meter check, ensure spiral weld nondestructive testing coverage of 100%. If there are defects, automatic alarm and spray tags, production workers to adjust process parameters, in a timely manner to eliminate defects.

After 7, cut into single pole, the head of every batch of structural steel pipe should be strictly check system, check the weld mechanical properties, chemical composition, amalgamation, steel tube surface quality, and through the nondestructive flaw detection, ensure that qualified pipe process, can be formally put into production.

Introduction of Polyurethane Foam

Polyurethane foam has good mechanical performance and adiabatic performance, usually can be 120 ℃ of heat-resistant, through the modification or combined with other heat insulation materials can be heat resistance of 180 ℃. Rigid polyurethane insulation pipe is black and white material mixed foaming and become a kind of thermal insulation pipe shell. White material mainly of phosphorus, glycerol polyether resin polyether resin and glycol polyether resin, you also need to add flame retardant, stable foam agent, and agent. Black material ingredient is more phenyl isocyanate, purity at 90%. The outside layer of glass fiber reinforced plastic is moistureproof layer of insulation structure, is made of fiber glass cloth impregnated resin, strong weathering and corrosion resistance, also has strong hardness 3. Single epoxy powder anticorrosive layer of epoxy powder anticorrosive is developed for nearly 30 years of compound wear-resisting pipe coating, electrostatic spraying technology on coating epoxy powder coating, film forming at a time. The coating is coated simple operation, no pollution, impact resistance and good resistance to bending performance coating, high temperature resistance, etc, outside the country has been widely used. Single epoxy powder pipe Anticorrosive double metal composite wear-resistant pipe products used in: coal mine: suitable for the coal mine underground water supply and drainage, shotcrete, positive negative pressure ventilation, drainage, gas, such as fire sprinkler carbon steel  pipe network. Power plant, thermal power plant process water waste residues, backwater pipeline.

Fire protection: to prevent spray, feed line has excellent adaptability of sprinkler system. Highway: electric power, communications, such as highway cable protection sleeve. Municipal engineering: for high-rise buildings water supply, heat supply network heating, water engineering, gas supply, such as underground water pipeline.

Such kind of coating steel pipe is much better in industry useful.

Classification of Welded Steel Pipe

1. The low pressure fluid conveying with galvanized welded steel pipe is also called galvanized welded steel pipe, commonly known as the white tube. Is used to transport oil, gas, air, water and heating steam, warm water generally low pressure fluid or other purposes such as hot dip galvanized welded steel pipe. Steel tube wall thickness is divided into ordinary galvanized steel pipe and thickening of galvanized steel pipe; To take over the side form is divided into without thread galvanized steel pipe and galvanized welded pipe with screws. Specifications of steel pipe in nominal diameter and nominal diameter is inside diameter of approximation.

2. Ordinary carbon steel wire casing is an industrial and civil construction and installation of machinery and equipment, such as electrical installation of the steel tube is used to protect the wire.

3. Straight seam welded steel pipe weld is parallel to the pole longitudinal steel pipe. Usually divided into metric welded steel pipe, welded thin-wall tube, transformer cooling pipe and so on.

4. The pressurized fluid conveying with spiral seam submerged arc welding pipe is hot rolled steel coil tube billet, often spiral shape, with double-sided submerged arc welding method, welding, used for pressurized fluid conveying spiral seam welded pipe. Steel tube confined ability, good welding performance, through strict scientific inspection and testing, the use of safe and reliable. Carbon steel pipe diameter is big, high transmission efficiency, and can save laying pipelines. Mainly used for conveying oil, natural gas pipeline.

5. Confined fluid conveying with high frequency welding steel pipe spiral seam is hot rolled steel coil tube billet, often spiral shape, using high-frequency welded lap welding method, used in pressurized fluid conveying spiral seam high frequency welding steel pipe. Steel tube confined ability, good plasticity, easy to welding and processing molding; After all kinds of strict and scientific inspection and testing, the use of safe and reliable steel pipe diameter is big, high transmission efficiency, and laying pipelines of investment can be saved. It is mainly used for laying of pipeline transport oil, gas, etc.

6. General low-pressure fluid conveying spiral seam submerged arc welding pipe is hot rolled steel coil tube billet, often temperature spiral forming, the double automatic submerged arc welding or one side welding into legal system for water, gas, air and steam general low-pressure fluid conveying with LSAW steel pipe.

7. General low-pressure fluid conveying with high frequency welding steel pipe spiral seam is hot rolled steel coil tube billet, often temperature spiral forming, adopting high-frequency lap welding welding for general low-pressure fluid conveying spiral seam high frequency welded pipe.

8. Pile with spiral weld pipe is hot rolled steel coil tube billet, often spiral shape, made of double-sided submerged arc welding or high frequency welding, used in civil construction structure, port, bridge foundation pile with structural steel pipe.