The Introduction of Spiral Steel Pipe

Spiral steel pipe, also called SSAW steel pipe or spiral welded spiral pipe, are made by hot rolled strip, it is made by extrusion forming under the normal temperature, and then welded by taking the technology of double wire and double-faced submerged-arc.

During molding process of spiral welded steel pipe, steel plate has uniform deformation and light residual stress, thus the surface has no scratches. Spiral steel pipe has more flexible thicknesses and diameters, especially in making high-grade thick pipes with small or medium aperture, these techniques has incomparable advantages in satisfying your needs.

Spiral steel pipe can be widely used in the production of large diameter spiral tubes for the following reasons:

1) as long as changing the forming angle, we can use the same width of the strip steel to produce a variety of caliber spiral pipe;
2) Since spiral welded steel pipe is formed by the continuous bending, the specified lengths of spiral steel pipe is not limited;
3) The weld in a spiral shape evenly distributed throughout the circumference of spiral steel pipe, so the dimensional accuracy of spiral pipe is high, and its strength is also high;
4) Spiral steel pipe is easy to change the size, so it is suitable for small batch and multi-species production.

Right Way to Save Spiral Pipe

Proper way to preserve spiral pipe

1) Storage space spiral steel pipe products or warehouse, should be selected in clean, smooth

drainage area, away from harmful gases or dust in factories and mines. The presence on the ground to clear the weeds and all the debris, keeping a clean steel

2) In a warehouse not with acid, alkali, salt, cement, steel and other aggressive materials stacked together. Different varieties of steel should be stacked separately, to prevent confusion, to prevent contact corrosion

3) Large steel, rail, steel disgrace, large diameter steel pipe, forgings, etc., may open dumps

4) Small and medium steel, wire rod, rebar, medium diameter steel pipe, steel wire and wire rope, etc., can be expected in a well-ventilated storage shed, but it must be the underlying thatch

5) Some small steel, sheet, strip, silicon, or thin-walled small-diameter steel pipes, all kinds of cold-rolled, cold-drawn steel products and high prices, corrosive metal products, can be stored for storage

6) A warehouse should be based on selected geographical conditions, the general ordinary enclosed warehouse, that is the roof with walls, doors and windows tight, with the Treasury ventilation device

7) Requires the Treasury sunny attention to ventilation, rain close attention to moisture, keep the appropriate storage environment

Common Defect Detection Method of Spiral Pipe

SSAW common defects magnetic particle testing or penetration testing. Spiral pipe magnetic particle testing or penetrant testing can be effectively found that surface cracks, folding, re-skin surface defects, hairline, pinholes. For ferromagnetic materials, magnetic particle testing method should be given priority, because of its high detection sensitivity; for non-ferromagnetic material, such as stainless steel spiral pipe, is used penetrant inspection method.

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Online austenitic steel spiral pipe, when the insulation is damaged or rain may have infiltrated the site, note that penetration testing to find stress corrosion cracking or pitting and other defects. However, magnetic particle or penetrant testing only on the outer surface of the pipe to detect internal defects in the surface of the powerless. The inner surface of the detector, especially crack type defect detection must be carried out by ultrasonic testing.

When the spiral pipe ends aside less resection margin, due to structural reasons detection device, spiral pipe ends head sometimes can not be effectively detected, and the end is the most likely site of the presence of cracks or other defects. If the spiral steel pipe ends there is potential for cracking tendency, weld heat affected during installation may also make potential crack. Therefore, it should be noted that after the detection of certain welded spiral steel area, to detect extended spiral steel tip defects.

Basic Knowledge of Welded Steel Pipe

Welded pipe is a common seen pipe which usually be used on fluid conveyance. Generally, it is defined to as the large diameter solder pipe, in accordance with the welding as a way for tube, the solder steel pipe consist spiral pipe and straight seam welding tube.

Based on the application, it can be divided into general welded pipe, galvanized welded tube, oxygen blowing metric pipe, welded tubes, wire casing, roller tube, deep well pump tubes, auto tube, transformer, electric soldering thin wall pipe, welded pipe and spiral welded tube.

Spiral welded pipe is the low carbon structural steel and low alloy structural steel strip according to certain helix Angle rolled into a tube billet, and then solder pipe joints made up, it can use a narrow strip in the production of large diameter steel tube, straight seam solder pipe is hot rolled plate after molding machine molding, roll deformation of steel coil for round cylinder, using frequent current skin effect and proximity effect or flux layer burning under the arc soldering, the tube billet is heated to melt, and fusion under certain extrusion effect, after the final cooling forming.

Welded tube is made of steel plate or steel strip after crimp forming, and then after welding. Divided into the form of the weld seam welded tube and spiral welded pipe, straight seam steel tube forming technique of common UOE forming process, JCOE steel pipe forming process.

Welding Tips of Spiral Pipe

Such as spiral steel pipe weld gap is too large, the effect of cuts constituting nearby, eddy current lack of heat, weld crystal adverse indirect co-occurrence of cracks or lack of fusion; if the gap is too small, the effect is increased near constitute, excessive heat welding to form weld seam burning; perhaps weld by kneading, rolling after composing pit, affecting the quality of the weld surface of the tube is heated to a marginal two welding temperature, under kneading roll kneading, together constitute the metal grain mutual penetration, crystallization, ending spiral steel pipe welds constitute strong kneading force is too small if, together constitute the number of crystals is small, the weld metal strength decreases, cracking may occur after the force; If kneading excessive force will make the molten metal is extruded weld situation, not only reduces the weld strength, and the list will be a lot of glitches, and even take the welding seam constitute disadvantages.

Quality Inspection of Spiral Pipe

Spiral pipe factory should be done before the mechanical performance test and flattening test, and flaring test, and to achieve the standard requirements. Straight seam steel quality inspection method is as follows:

1, From the face of it, that is visual inspection. Visual inspection of welded joints is a simple procedure but widely used test method is an important part of product testing, the main defects and deviations are found on the surface of the weld size. Usually by the naked eye, with the standard model, gauge and test tools such as a magnifying glass. If the weld surface defects, weld defects there may be internal.

2, Physical test methods: physical test method is to use some physical phenomena assay or test method. Or within the workpiece material defect inspection, and are generally used NDT methods. NDT ultrasonic flaw detection, radiation detection, penetration testing, magnetic testing and so on.

3, Pressure vessels strength test: pressure vessels, in addition to tightness test, but also the strength test. There are common test of two hydraulic test and air pressure. They can be tested in working under pressure vessels and piping welds compactness. Hydrostatic pressure test is more sensitive than the test speed and, at the same time after the test products do not waste water treatment, drainage problems for the product is particularly applicable. But the risk is greater than the test pressure test. When tested, it must comply with the appropriate safety measures to prevent accidents during the test.

4, Compact test: liquid or gas storage vessel welding, which is not dense weld defects, such as penetrating cracks, pores, slag, incomplete penetration loose tissue and the like, can be used to find the density test. Compactness test methods are: kerosene test, carrying water testing, water will test etc.

5, Hydrostatic test: each pipe hydrostatic test should be done without leakage test pressure press Calculate P = 2ST / D where S- hydrostatic test stress test Mpa, hydrostatic test stress testing in accordance with corresponding steel standard specifies the minimum degree of yield (Q235 is 235Mpa) 60% of the selection.

How to Properly Stack Spiral Pipe

Spiral pipe stacked right help protect the quality of spiral steel pipe, spiral steel pipe prolong life, prevent deformation, erosion, so orderly stacking spiral steel pipe, but also conducive to late spiral pipe loading, inventory. Spiral Pipe buyers should also strictly in accordance with the requirements of spiral steel pipe pile.

1) Spiral pipe open dumps, following necessary pad with wood or stone, stack surface needs slightly tilted to facilitate drainage, and pay attention to the material placed flat to prevent the causing bending.

2) Spiral pipe principle requires stacking under palletizing firm to ensure the safety of the premise, to do according to species, palletizing specifications, different varieties of materials to palletizing respectively, to prevent muddy and mutual erosion, but also easy to install a library car.

3) Prohibit storage of steel aggressive action items in spiral steel pipe pile position around.

4) Spiral steel pipe pile bottom should be padded, strong, smooth, prevent moisture or material deformation,

5) The same material by successively respectively stacking storage.

6) Sspiral steel stacking height, artificial homework does not exceed 1.2m, mechanical homework does not exceed 1.5m, stack no larger than 2.5m,

7) Be left between the stacks and stacks of certain passages, check road is generally O. 5m, of access depending on the size and material transport machinery, generally is 1.5 ~ 2.0m,

8) Open dumps angles and channels should stoop to put that mouth down, beam shall stand up, you can not be up and groove steel to avoid rusting water.

9) The end of booster stack, if the warehouse sunny cement floor, to elevate O.1m, if the mud shall booster O.2 ~ 0.5m. If it is open space, concrete floor booster 0.3 to 0.5 m, the surface mud booster 0.5 ~ 0.7m.

Design Conditions of Spiral Pressure Pipeline

On engineering, process operating parameters should not be used directly as a pressure pipeline design conditions, factors to consider process operating fluctuations, the impact of connected devices, environmental impact, etc., and on the basis of operating parameters of the process are given a certain amount as a design safety margin condition. Design conditions mentioned here mainly refers to the design pressure and design temperature.

SSAW steel pipe design pressure: when should not be less than the normal operating pressure under the most demanding conditions by the internal pressure (or external pressure) and temperature constituted.

The most severe conditions: is the lead pipe and piping components maximum wall thickness or the maximum nominal pressure rating conditions.

Design pressure determination: consider the medium hydrostatic pressure and other factors, the design pressure should generally be slightly higher than the maximum working pressure under the most demanding conditions by (or on) the external pressure and temperature constituted.