Spiral steel pipe insulation products venues or warehouses should be selected in a clean, well-drained place, away from the production of harmful gases or dust factories and mines. Cut into a single pipe, the first batch of three steel pipe to the first inspection system to check the mechanical properties of the weld, chemical composition, melting conditions, the surface quality of spiral steel pipe and non-destructive testing to ensure that the pipe making process qualified , Can formally put into production. Spiral steel pipe production process is simple, high production efficiency, low cost and rapid development. In the venue to remove weeds and all debris, keep the steel clean. In the warehouse shall not be acid, alkali, salt, cement and other steel pipes are erosive materials stacked together. Spiral pipe more than a month later, the problem finally emerged. A CISA member who asked not to be named told the China Business reporter that according to what they now have, even the most conservative estimates, 70% of the enterprises are in production or limited production. When the pipe is subjected to internal pressure, there are usually two main stresses on the pipe wall. Spiral pipe strength is generally higher than the straight seam welded pipe, the pipe can be used to produce a narrower diameter larger pipe, you can also use the same width of the billet production of different diameter pipe. Adopt the weld gap control device to ensure the weld spiral steel pipe gap to meet the welding requirements, pipe diameter, the wrong side of the amount and the weld gap are strictly controlled. Internal welding and external welding are using the United States Lincoln welding machine for single-wire or double-wire submerged arc welding, to obtain a stable welding specifications. More than a month ago, the EU decided to carry out a double reverse survey on China's spiral steel pipe. Immediately afterwards, the United States followed suit. All of this is directly related to the interests of more than 3,000 helical steel pipe manufacturers in China. Prior to this, the production capacity in this area was mostly designed according to export. Spiral pipe strength is generally higher than the straight seam welded pipe, the pipe can be used to produce a narrower diameter larger pipe, you can also use the same width of the billet production of different diameter pipe. But with the same length of straight pipe, the weld length increased by 40 ~ 100%, and the production rate is lower. The outer diameter of the pipe for the spiral steel pipe is indicated by the letter D, followed by the additional outer diameter of the size and wall thickness, such as the outer diameter of 105 spiral steel pipe, wall thickness 6MM, with D107 * 5 said plastic pipe Outer diameter, such as De63, other such as reinforced concrete pipe, cast iron pipe, galvanized pipe using DN said that the general use of nominal diameter in the design drawings that nominal diameter is designed to facilitate the manufacture and maintenance of man-made one Species standards, but also more than the nominal diameter, is the pipe (or pipe) specification name.
Corrosion-resistant spiral steel pipe
Spiral steel pipe in the factory before the mechanical properties should be tested and flattening test and flaring test, and to meet the standards required. Straight seam steel quality testing methods are as follows:
1, judging from the surface, that is, appearance inspection. The appearance of the welded joint inspection is a simple and convenient procedure for a wide range of test methods, testing is an important part of the content, mainly to find the weld surface defects and dimensional deviations. Generally through the naked eye, with standard templates, gauges and magnifying glass and other tools for testing. If the weld surface defects, there will be defects within the weld may be.
2, the physical test method: Physical test method is to use some of the physical phenomena of the test method or test. Inspection of defects in materials or workpieces is generally by nondestructive testing. Non-destructive testing ultrasonic flaw detection, ray inspection, penetrating inspection, magnetic inspection.
3, the strength of the pressure vessel inspection: Pressure vessels, in addition to sealing test, but also for strength test. There are two common water pressure test and pressure test. They all verify the weld tightness of vessels and pipework under pressure. Air pressure test is more sensitive and faster than hydrostatic test, and the tested product does not need to be drained, especially for products with difficult drainage. But the test is more dangerous than the hydrostatic test. During the test, the corresponding safety technical measures must be observed to prevent an accident during the test.
4, the tightness test: storage of liquid or gas welding container, the weld is not dense defects, such as penetration of cracks, pores, slag, incomplete penetration and loose tissue, etc., can be used to identify the tightness test. Tightness test methods are: kerosene test, water test, water test and so on.
5, hydrostatic test hydrostatic pressure test should be done for each pipe without leakage phenomenon, press the test to calculate the test pressure P = 2ST / D Where S-hydrostatic test stress Mpa, hydrostatic test test stress corresponding Steel strip standard minimum yield (Q235 235Mpa) of 60% selected. Regulating time: D <508 Test pressure holding time of not less than 5 seconds; D ≥ 508 Test pressure holding time of not less than 10 seconds 4 Non-destructive testing of steel pipe repair weld, X-ray or ultrasonic inspection. Spiral welds in steel for flammable common fluids are to be subjected to 100% SX-ray or ultrasonic inspection. Spiral welds of steel pipes used for the delivery of common fluids such as water, sewage, air, heating steam, etc. shall be subjected to X-ray or Sonography checks (20%).
According to the spiral pipe quality inspection results, usually divided into three types of spiral steel pipe: qualified products, rework and waste products. Qualified product refers to the appearance of the quality and internal quality of the relevant standards or delivery acceptance of the technical conditions of the spiral steel; rework refers to the appearance of the quality and internal quality does not fully meet the standards and acceptance of the article, but allows rework, after rework to meet the standards and acceptance conditions Of the Spiral Pipe; Waste refers to the appearance of quality and internal quality unqualified, does not allow repair or rework still can not reach the standard and acceptance conditions of the spiral steel pipe.
Corrosion-resistant spiral steel pipe
Seamless steel tubes occupy an important position in the national economy, perhaps friends are not very understanding of it, but it has been widely invested in petroleum and chemical and other aspects, has brought great convenience to people's lives . Seamless pipe is also divided into many categories, including stainless steel pipe in real life is widely used. In life is not difficult to find people see the garden fence and staircase handrails, etc., are used stainless steel tube. Stainless steel tubes have precise dimensions for easy installation. It also has good corrosion resistance and therefore reduces many unnecessary expenses, especially when it is used as a garden fence, in a humid environment will not be corroded. Stainless steel pipe also has a strong toughness, but the toughness and the size of the hole diameter is directly linked to, as a support, often smaller than the diameter of stainless steel pipe used as a guardrail hole diameter small. Therefore, friends in the purchase process, according to their needs to buy seamless steel tubes. How to distinguish between the quality of thick-walled seamless steel pipe quality standards? The primary quality of thick-walled seamless steel pipe is uniform in composition, looks very regular cut in the head, feeling is a kind of smooth feel, and Not a glitch feeling. So if it is incomplete information, it is rough in the cut, and all the pipes look dull. If it is fake thick-walled seamless steel pipe, then there will be particularly significant in color, is showing a reddish color, there are second-order thick-walled seamless steel pipe in the temperature is not up to standard. There is a fake thick-walled seamless steel pipe is not a circular cross-section may be oval may be other shapes, which is because the manufacturers save data, cut corners of the results, so it does not fit the dimensions The specification. There is also the appearance of scarring, which is not allowed in the quality of thick-walled seamless steel pipe, but the residual thick-walled seamless steel pipe is easy to see this appearance. What is high pressure seamless pipe? It is a kind of boiler tube, which belongs to the category of seamless steel pipe. Manufacturing methods and seamless steel pipe the same, but the steel used in the manufacture of steel have certain strict requirements. Since high-pressure boiler tubes are often used under high temperature and high pressure conditions, the high-pressure boiler tubes are mainly used to manufacture superheater tubes, reheater tubes, steam pipes and main steam pipes of high-pressure and extra-high pressure boilers.
