Q355b thick wall welded pipeInspection requirements

It is important that the thick wall coiled pipe will not damage the performance of raw materials. The disadvantage of hot roll thick wall rolling pipe is that the treatment time is long Very expensive. Thick wall rolling pipe is widely used: cylinder, hydraulic, bridge, roller, it is difficult for general machinery and equipment, so it is necessary to use coiled pipe. First, after the steel plate is rolled, then weld the two rolled steel pipes. The weld is also called T-welding. Sometimes, the large diameter thick wall straight seam steel needs to roll and weld the two steel plates, Therefore, there may be two welds on a pipe body, also known as double welds. Thick wall straight seam coiled pipe has a wide range of materials. As long as it is a steel plate that can be ordered in a steel plant, it is basically OK. The main problem of the product is the welding quality. The welding quality directly determines the quality of the product, which is the main step in the thick wall rolling pipe. It is suitable for columns for bearing steel structures such as buildings, bridges, dams and offshore platforms, super long-span building structures and electric pole tower and mast structures requiring wind resistance and earthquake resistance.

.The parts with continuous acoustic flaw detection marks on the weld shall be rechecked by manual ultrasonic and X-ray. If there are defects, after repair, they shall be subject to nondestructive inspection again until it is confirmed that the butt weld of strip steel and the pipe of T-joint intersecting with spiral weld have all passed the X-ray television or film. Each steel plate coil has passed the hydrostatic test, and the pressure adopts radial sealing. The test pressure and time are strictly controlled by the microcomputer detection device of steel plate rolling pipe water pressure. Why are there two longitudinal welds in the same pipe section of rolling pipe?

Recently, with the rapid development of excellent strip continuous rolling production and the progress of welding and inspection technology, the weld quality has been continuously improved, and the application field is relatively wide, so as to gradually replace the seamless steel pipe. The main one is the technological development of welded pipe. Our welded pipe is made of steel plate or strip steel and welded after crimping. It is generally a welding process, which improves the production efficiency and service quality of welded pipe.

.The wall thickness of coiled pipe like coiled pipe is under 20mm and the outer diameter is 450-3000mm. It is made of steel plate by direct rolling, welding, butt joint and rebar removal. Coil pipe has the characteristics of short processing time, rapid delivery and low cost. The rolling pipe is mainly used for pipes, billboards, columns, etc.

The products are widely used in petroleum, chemical industry natural gas transportation, pile driving and urban water supply, heating, gas supply and other projects. The wall thickness of the hot-rolled thick wall coil of retailers generally exceeds 20mm, and the outer diameter range is 450-3000mm. The hot-rolled thick wall coil is rolled, welded, formed, de reinforced, flaw detected and delivered under the state of steel plate heating. Sometimes the wall with special thickness needs secondary heating. It is characterized by small outer diameter tolerance and uniform wall thickness. The main thing is that the hot-rolled thick wall quality management coil will not damage the performance of raw materials. The disadvantages of hot-rolled thick wall coil are long processing time and the diameter of thick wall coil is generally above dn450.

When the pipe is rolled, the distance between the two welds shall be greater than 100mm, and the distance between the outer wall of the outer branch pipe shall not be less than 50mm.

However, the disadvantages of manual cutting and cutting are also obvious, and the quality of the incision is very poor Big size error There is a great waste of materials The post-treatment process has large processing capacity and poor working conditions. Cutting with a forming machine can greatly improve the quality of the workpiece but the workpiece must be pre machined. It is not suitable for blanking of single chip, small batch and large workpiece. Although the semi-automatic cutting machine reduces the labor intensity, its function is simple and is only suitable for cutting two shapes. Due to the low cost of equipment, the above cutting is easy to operate compared with CNC cutting Easy to operate, so even in some large enterprises, it is still widely used in small and medium-sized enterprises.

How about thick wall coiled pipe? Generally, chemical and electrolytic pickling are used for pickling treatment. Only chemical pickling is used for thick wall coiled pipe, which can remove oxide scale, rust and old coating. Sometimes it can be used as reprocessing after sand blasting. Although chemical cleaning can make the surface reach a certain cleanliness and roughness, its anchor lines are shallow and easy to pollute the environment. Under the action of abrasive impact and force, the steel pipe can also achieve the required uniform roughness.

In general, the hot coil pipe is mainly committed to the production of all kinds of circumferential seam and longitudinal ring coils and steel penstocks. It is reformed on the basis of traditional coil equipment and similar specifications and models, so that all parameters of the hot coil pipe can be improved, filling the gap that the original traditional coil equipment can not produce. In addition, the hot coil pipe needs attention. The following matters are required: before processing, the hot coil pipe needs to be familiar with the technical requirements of paper, process material properties and other related aspects, select an appropriate hot coil machine, determine whether the cold coil, warm coil or hot coil, chemical industry, natural gas transportation, pile driving and urban water supply, heating gas supply and other projects. The wall thickness of the hot-rolled thick wall coil of retailers generally exceeds 20mm, welded and the outer diameter range is 450-3000mm. The hot-rolled thick wall coil is rolled, formed, de reinforced, flaw detected and delivered under the state of steel plate heating. Sometimes the wall with special thickness needs secondary heating. It is characterized by small outer diameter tolerance and uniform wall thickness. The main thing is that the hot-rolled thick wall quality management coil will not damage the performance of raw materials. The disadvantages of hot-rolled thick wall coil are long processing time and the diameter of thick wall coil is generally above dn450.

Gas and other projects.

Main technical measures for low hardening trend

It has advantages and quality. The weld reinforcement obtained is increased, the weld formation is deteriorated and the edge transition is poor.

Quality assurance.During pipe rolling, the surface damage of steel plate shall be prevented. The parts with serious scratches must be polished for transition, and the wall thickness of the polished parts shall not be less than the design wall thickness.

Spiral pipe not only has high quality, such as higher flame retardancy, higher Vicat temperature, higher volume resistivity, higher strength and smaller friction coefficient. At the same time, it also has the functions of bending and coil. It is specialized in products and renewable resources business including hot-rolled steel pipe, large-diameter thick wall coiled pipe, thick wall straight seam coiled pipe, steel casing and coiled pipe factory

For external welding, a larger welding current is used. However, under the condition of high welding current, the stirring effect of molten pool is enhanced, resulting in the increase of weld reinforcement, the deterioration of weld formation and poor edge transition.

.The continuous pipe has good characteristics and performance in use, and advanced technology is adopted. If we want to make progress and enhance competitiveness, we must have a good opportunity at present. Just like the development of the iron and steel industry, although the pipe rolling industry has made remarkable achievements in recent years, accounting for more than 1 / 4 of the world's output, there is still a certain gap with the international advanced level in terms of technical equipment, product quality and product grade, enterprise economic scale and main technical and economic indicators. The coil adopts PLC automatic system,Q345B large diameter reel,16Mn thick wall welded pipe, and each part is operated on the panel. The cutting length of winding tube adopts photoelectric induction, accurate positioning and automatic cutting. Each process adopts double pump oil pressure system to ensure stable operation. The pipe rolling has different application ranges: winding pipe length: 0-1400mm, winding pipe thickness: 2-15mm,16Mn large diameter thick wall coiled pipe, winding pipe diameter: 20-200mm purpose: 3 inches x24x, working voltage: 380V, 50Hz. It can be used according to the specified parameters and scope, so as to ensure that it can play an important role and value in use. Large coil is durable, stable and easy to operate. The packaging process of coil includes filling, packaging, sealing and other main processes, stacking and disassembly. In addition, the rolling process also includes measuring or stamping on the package. Using mechanical packaging products can improve productivity, reduce labor intensity, meet the needs of large-scale production and meet the requirements of cleanliness and hygiene. With the emergence of new packaging materials and the continuous innovation of packaging technology, spiral pipe can play an important role and value in different industries and fields.

When the nominal diameter is greater than or equal to 600mm, back welding shall be carried out in the pipe.

The influence of welding process parameters on welding current mainly includes two aspects: according to the production characteristics of spiral steel pipe, small welding current is usually used for internal welding