We usually contact is fitting, but for the true definition of pipe fittings must be not all people know. The so-called fitting, is to pipe connection into line parts. According to the connection method can be divided into the socket type pipe fittings, flanges threaded pipe fittings, pipe fittings and welding pipe fittings four classes. Use the same as the pipe materials. Elbow (elbow), flange, tee, four-way tube (cross) and reducer (reducer), etc. Bend to turn his arm; Flange is used to make the pipe with pipe connecting parts, connection pipe, tee to the meeting-place of three tube; Cross pipe used in the meeting-place of four tube; Reducer is used for different pipe diameter of two pipes are connected.
Boiler steel tube refers to both ends open and has a hollow section, the length and the surrounding of the larger steel, according to the production methods can be divided into seamless steel pipe and welded steel pipe, boiler steel pipe specifications with overall dimensions. Boiler steel pipe (such as the diameter or length) and wall thickness, according to the size range is very wide, from small diameter capillary until several meters in diameter, large diameter pipe. Steel pipe can be used in the pipeline, thermal technology equipment, industrial machinery, petroleum geological exploration, containers, chemical industry, and special purpose. The classification of steel pipe: steel pipe seamless steel pipe and welded steel pipe (tube) two kinds big. According to the cross section shape and can be divided into circular tube and special-shaped tube, steel tube is widely used, but there are some square, rectangle, semicircle, hexagonal, equilateral triangle, octagonal special-shaped steel tube. For fluid under pressure steel pipe are hydraulic experiment was carried out to test the compression ability and the quality, under the pressure of regulation does not leak, soaked or expansion of qualified, some steel pipe according to the standard or the buyer requires edge test, flaring test, flattening test, etc
In June,2016, Hunan Great Steel Pipe Co., LTD. received a challenge order with below request and conducted researches immediately:
1) Pipe Specification: Φ1219 * 28.6 * 12000 mm, Steel Grade: API 5 l PSL2 X70M
2) At temperature -41℃，for V-shaped notch specimen, CVN test from welding seam and HAZ, minimum impact value for single specimen shall ≥30J and average impact value shall ≥40J. And CVN test from base material, minimum impact value for single specimen shall ≥60J and average impact value shall ≥80J.
After multiple welding procedure tests, Yulong has successfully optimized the existing welding procedure which is adopted during the pilot production. And after various physical and chemical properties testing and quality inspection for the pilot produced pipe, all the quality indexes of the carbon steel pipe are satisfied with specification standard and customer requirements. Since getting the production approval from the customer, we have already produced 4866MT qualified pipes.
The successful production of DSAW steel pipe with large diameter, thick wall thickness and high steel grade under -41℃ low temperature impact test requirements marks Jiangsu Yulong Steel Pipe Co., LTD. has gained a big breakthrough in pipe manufacturing technology and will have a greater advantage in the future market competition.
LSAW steel pipe is steel plate production, and is used in the production of spiral welded pipe hot rolled coil. The rolling process of hot strip mill has a series of advantages, which has the ability of producing high quality pipeline steel. For example, a water cooling system is installed on the output stage to accelerate the cooling, which allows the use of low alloy components to achieve a special strength grade and low temperature toughness, thereby improving the ability of the steel to be welded. But this system in the steel plate production plant basically did not. The content of alloy coil (carbon equivalent) are often lower than similar grades of steel, it also improves the weldability of spiral welded steel pipe. More to the point, as a result of the spiral welded pipe plate rolling direction is vertical pipe axis direction (the clip solution depending on the steel pipe of the spiral angle), and straight seam steel pipe plate rolling direction vertical to the axis direction of the steel pipe. Therefore, the crack resistance of spiral welded pipe material is better than straight seam steel pipe.
In welding process, spiral welded pipe and straight seam steel pipe welding method is consistent, but straight seam welded pipe inevitably will have a lot of T-shaped seam, so the existence of welding defects but also greatly enhance the probability, and T-shaped seam welding residual stress force is larger, the weld metal often in triaxial state of stress, increase the possibility of cracks. Moreover, according to the process of submerged arc welding, each weld should have arc ignition and extinguishing tube when the pressure is under internal pressure, usually on the tube wall to produce two main stresses, namely, the radial stress Delta Y and the axial stress Delta X. The synthesis of Y (l/4sin2 alpha +cos2 alpha) 1/2, which is the helix angle of the welded joint of the spiral welded pipe. Spiral welded pipe seam angle is 50-75 degrees, so the stress synthesis of spiral weld seam welded pipe is principal stress 60-85%. In the same work under pressure, with a diameter ratio of spiral welded pipe wall thickness can be reduced. According to the above characteristics:DSAW steel pipe Bao Po, due to the weld is to be force and resultant stress is relatively small, Bao Po mouth is generally not originated in the spiral seam and its safety better than straight seam welded steel pipe is high.