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What inspections do submerged arc steel pipes need to go through after production

Views: 0     Author: Site Editor     Publish Time: 2022-12-28      Origin: Site

In the process of producing submerged arc steel pipes, the temperature must be strictly controlled, to ensure the reliability of welding. If the temperature is too low, it may cause the welding position to fail to reach the temperature required for welding. When most of the metal structure is still solid, it is difficult for the metals at both ends to penetrate and bond together. At that time, when the temperature was too high, a lot of metal in the welding position was in a molten state. The texture of these parts was very soft and had corresponding fluidity, and there might be molten droplets. When such metals dripped Again there is not enough metal for interpenetration. And when welding, there will be some unevenness with the weld to form a molten hole. Therefore, manufacturers of integrated sewage treatment equipment remind them that the temperature should be strictly controlled in the production process of submerged arc steel pipes. Regular manufacturers have advanced control technology, so in the process of production, the temperature control requirements can be realized to ensure product quality, so we need to buy submerged arc steel pipes from regular manufacturers.


Submerged arc steel pipe can be used for liquid transportation: water supply and drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: as piling pipes, as bridges; pipes for wharves, roads, building structures, etc. A submerged arc steel pipe is a spiral seam steel pipe made of strip steel coil as raw material, extruded at regular temperature, and welded by the automatic double-wire double-sided submerged arc welding process. The head-to-tail butt joint of strip steel adopts single-wire or double-wire submerged arc welding, and automatic submerged arc welding is used for repair welding after being rolled into steel pipes. It adopts external control or internal control roll forming. Both internal and external welding adopt foreign Lincoln electric welding machines for single-wire or double-wire submerged arc welding, to obtain stable welding specifications.


What inspections do submerged arc steel pipes need to go through after production?

(1) Hydrostatic test: On the hydrostatic testing machine, inspect the expanded steel pipes one by one to ensure that the steel pipes meet the test pressure required by the standard. The machine has automatic recording and storage functions;

(2) Diameter expansion: The full length of the submerged arc steel pipe is expanded to improve the dimensional accuracy of the steel pipe and improve the distribution of internal stress of the steel pipe;

(3) X-ray inspection II: Carry out X-ray industrial TV inspection and filming of pipe end welds on steel pipes after diameter expansion and hydrostatic test;

(4) Magnetic particle inspection of pipe ends: This inspection is carried out to find pipe end defects;

(5) X-ray inspection Ⅰ: Carry out X-ray industrial TV inspection of internal and external welds, and use an image processing system to ensure the sensitivity of flaw detection;

(6) Check the inner and outer welds of the spiral steel pipe and the base metal on both sides of the weld;

(7) Sonic inspection II: conduct acoustic inspection one by one again to check possible defects of straight seam welded steel pipes after diameter expansion and hydraulic pressure;

(8) Chamfering: process the pipe end of the qualified steel pipe to meet the required bevel size of the pipe end;

(9) Anti-corrosion and coating: The qualified steel pipes are anti-corrosion and coating according to user requirements.


The submerged arc steel pipe fittings and assemblies prefabricated in the processing plant must be fully completed, that is, all welding joints have been welded, the flange joints are installed, long-term backing plates are installed, and all flange bolts are threaded and tightened. The design value of the deviation of the external dimension of the submerged arc steel pipe assembly cannot exceed the following regulations; when the external dimension of the submerged arc steel pipe assembly is 3m, the deviation is ±5mm, and when the external dimension of the submerged arc steel pipe assembly increases by 1m, the deviation value It can be increased by ±2mm, but the total deviation cannot be greater than ±15mm.


Hand-welded assemblies with flanged connections or valves are subject to the test. All assemblies shall be marked according to the spool specified in the drawing, and the outlet end shall be closed with a blind plate or a plug. The outlet flange of the upper pipe end of the assembly can be welded firmly if the flange bolt holes are evenly distributed. If it is the flange connected to the equipment or the flange connected to the branch flange of other assemblies, it can only be positioned by spot welding at the pipe end, and it can only be welded firmly after being transported to the installation site for positioning. Valves should also be installed on the assembly, and the short pipes for the installation of the sewage and vent pipes and the elevation marks for the installation of the sliding bracket should be welded. The prefabricated pipe sections should be cleaned inside. The submerged arc steel pipe assembly should consider the convenience of transportation and installation and have an adjustable live opening, and it should also have sufficient rigidity to prevent long-term deformation.