Spiral steel pipe is a spiral seam steel pipe, which is made of strip coil plate as raw material, often formed by warm extrusion, and welded by automatic double-wire and double-side submerged arc welding process. 

Cangzhou Shenlong Pipe Manufacturing Co., Ltd. produces large diameter spiral steel pipe, straight seam welded pipe, the company has passed the ISO9001R certification, the whole product is tested according to the standard, recently our company has just delivered a batch of spiral steel pipe, used in the Philippines water supply project, the specification is DN300-DN1200, hope that more customers choose our products. We will try our best to serve every customer and deliver every order.

Before leaving the factory, the spiral steel pipe should be subjected to mechanical performance test, flattening test and flaring test, and meet the requirements specified in the standard. Quality inspection methods are as follows:

1, judging from the surface, that is, in the appearance of inspection. The appearance inspection of welded joint is a simple and widely used inspection method. It is an important content of finished product inspection, mainly to find the defect of weld surface and the deviation of size. Generally through naked eye observation, with the help of standard template, gauge and magnifying glass and other tools for inspection. If there are defects on the weld surface, there may be defects in the weld.

2, the physical method of inspection: the physical inspection method is to use some physical phenomena to determine or test the method. The inspection of internal defects of materials or workpieces is generally carried out by nondestructive testing. Non-destructive inspection has ultrasonic inspection, ray inspection, penetration inspection, magnetic inspection and so on.

3, pressure vessel strength test: pressure vessel, in addition to the sealing test, but also to carry out the strength test. There are two common hydrostatic test and pressure test. They can test the weld density of vessels and pipes working under pressure. Air pressure test is more sensitive and faster than water pressure test. At the same time, the products after the test do not need to be drained. It is especially suitable for the products with difficult drainage. But the test is more dangerous than the hydrostatic test. When conducting the test, the corresponding safety technical measures must be observed to prevent accidents during the test.

4, compactness test: storage liquid or gas welding containers, the weld is not compact defects, such as penetrating cracks, pores, slag, penetration and loose organization, can be found by compactness test. Densification test methods include kerosene test, water load test, water flush test, etc.

5, hydrostatic test each steel pipe should be done hydrostatic test without leakage phenomenon, test pressure according to the test calculation P=2ST/D in the S-hydrostatic test stress Mpa, hydrostatic test stress according to the corresponding steel strip standard specified yield small value (Q235 is 235Mpa) 60% selected. Voltage stabilization time :D< 508 test pressure holding time not less than 5 seconds; D≥508 Test pressure holding time not less than 10 seconds 4 Non-destructive testing The repair weld of steel pipe, the head weld of steel belt and the ring seam shall be inspected by X-ray or ultrasonic. 100% SX-ray or ultrasonic inspection shall be carried out on the spiral welds of the steel direction used for the transport of combustible common fluids, and X-ray or ultrasonic inspection shall be carried out on the spiral welds of the steel pipes used for the transport of water, sewage, air, heating steam and other common fluids (20%).

According to the quality inspection results of spiral steel pipes, spiral steel pipes are usually divided into three categories: qualified products, repaired products and waste products. Qualified products refer to spiral steel pipes whose appearance quality and internal quality meet relevant standards or technical conditions for delivery acceptance; The repaired product refers to the spiral steel pipe whose appearance quality and inner quality are not fully in line with the standard and acceptance strip body, but it is allowed to be repaired, and can reach the standard and acceptance conditions after repair; Scrap refers to the spiral steel pipe whose appearance quality and inner quality are not qualified, which is not allowed to be repaired or still cannot meet the standard and acceptance conditions after repair.

Waste is divided into two types: inner waste and outer waste. Inner waste refers to the scrap spiral steel pipe found in the foundry or casting workshop; Outer waste refers to the waste found after delivery of spiral steel pipe, which is usually exposed in the process of mechanical processing, heat treatment or use. The economic loss caused by it is far greater than that of inner waste. In ORDER TO REDUCE external WASTE, mass production of spiral steel pipes SHOULD be sampled for experimental heat treatment and rough machining before leaving the factory, and potential defects of spiral steel pipes should be found in spiral steel pipe factory as far as possible, so that necessary remedial measures can be taken as soon as possible.