In this article, we will talk mainly about the production process of the big straight welded pipe, and to make you know clearly what the process all included.
Introduction of Domestic Big Straight Seam Welded Pipe Production Technology
Straight seam welded pipe is made of steel plate or steel strip after bending forming, and then by welding. And it can be divided into the weld seam welded pipe and spiral welded pipe by the welding forming method. According to the application, it is divided into general welded pipe, galvanized welded pipe, oxygen blowing metric welded pipe, welded pipe, wire casing, roller tube, deep well pump pipe, auto tube, transformer, electric welding thin wall pipe, welded pipe and spiral welded pipe.
The main production process of big straight welded pipe:
1.Plat detection: The plate used in the manufacturing of large diameter submerged-arc welding straight seam steel pipe, the plate should have the ultrasonic inspection in the first after being put into the production line;
2.The edge milling: to have double-sided milling by edge milling machine to make it meet the requirements of plate, plate edge parallelism and groove shape;
3. The bending edge: the have preflexing by using the preflexing machine to make the edge of proper curvature;
4.Molding: to timely punching the half of the preflexing steel by using the JCO forming machine, and to form it into a “J” shape, and then bend the other half of the steel plate, to the shape “C”, and eventually forming the opening “O” shape;
5. Pre-welding: to joint the forming of straight seam welded steel pipe and continuously weld by adopting gas protection welding;
6. The inner welding: by adopting multiple wire submerged arc welding to have inner welding of the straight seam welded steel pipe;
7. The outer welding: by adopting multiple wire submerged arc welding to have outer welding of the straight seam welded steel pipe inside;
8. Ultrasonic inspection Ⅰ: to have 100% inspection of inside and outside of straight seam welded steel pipe weld and both sides of the base;
9. X-ray Ⅰ inspection: to have 100% X-ray inspection inside and outside of the weld, and using image processing system to ensure the sensitivity of detection;
10. Expanding: to improve the size precision of the steel tube by expanding the length of the submerged arc welding, and improve the distribution of stress in steel tube;
11. Hydraulic pressure test: test the steel pipe after expanding on the hydrostatic testing machine to ensure the test pressure of steel tube meet the standard requirements, the machine has the function of automatic recording and storing;
12.Chamfering: to process the end of the pipe after the inspection of steel pipe to meet the requirements of tube end groove size;
13.The ultrasonic inspection Ⅱ: again to check whether the pipe has defects after expanding and water pressure by ultrasonic inspection;
14.X-ray Ⅱdetection: to check the steel pipe by using X-ray industrial TV after expanding and water pressure and take picture of the pipe end;
15.The pipe magnetic powder inspection: check on this to find out the pipe defect;
16. Corrosion protection and coating: qualified steel pipe according to user requirements for corrosion protection and coating.
In the next article, we will have information on the analytic description of the dry welding technology of large diameter thick wall welding.