SSAW Steel Pipe Manufacturing Process

SSAW Steel Pipe (Spiral Submerged Arc Welded Pipe) uses steel strip as raw material. The strip is continuously fed into a forming unit at a certain angle, and gradually rolled into a spiral cylinder shape by rollers. Simultaneously, submerged arc welding is performed on both the inner and outer sides to form a continuous weld seam.

Advantages:
Multiple diameter pipes can be produced from the same width of steel strip; 

The weld seam is at a certain angle to the pipe axis, avoiding principal stress and resulting in better stress distribution; 

Suitable for large-diameter (219mm~3600mm) and medium-wall-thickness (3.2mm~25.4mm) pipelines.

Limitations:
The weld seam length is 30%~100% longer than that of straight seam welded pipe, theoretically resulting in a higher probability of defects; 

The geometric dimensional accuracy is slightly inferior to that of straight seam welded pipe; 

It is generally only suitable for Class 3 and Class 4 areas (oil and gas long-distance pipeline design specifications).

SSAW Steel Pipe Manufacturing Process: 

(1) raw materials that strip, wire, flux. Must go through rigorous testing before being put into the physical and chemical. 

(2) strip head and tail docking, using single or double wire submerged arc welding, in rolled steel by automatic submerged arc welding. 
(3) Before molding, the strip after flattening, cutting, trimming, planing, surface cleaning and transportation to the curved edge treatment. 
(4) the use of electrical contacts on both sides of the conveyor control the pressure cylinder pressure to ensure the smooth delivery of the strip. 
(5) the use of internal or external control roll forming. 
(6) the weld gap control device to ensure that the weld gap to meet the welding requirements, diameter, volume and the wrong side of the weld gap have been strictly controlled. 
(7) the welding and soldering are used outside the United States Lincoln welding machine for single or double wire submerged arc welding, to obtain stable welding specifications. 
(8) After welding the weld line continuous ultrasonic injury checked to ensure 100% coverage of non-destructive testing of spiral weld. If defective, automatic alarm and spraying tags, production workers so adjusting the process parameters, and remove defects. 
(9) the use of air plasma cutting machine to cut a single tube. 
(10) cut into a single pipe, each batch of steel should be carried out strict inspection system, inspection of weld mechanical properties, chemical composition, fusion status, steel surface quality and after NDT inspection process to ensure that qualified pipe before they can formally put into production. 
(11) there is a continuous sonic flaw marks the site of the weld, manual ultrasonic and X-ray review, if there are defects after repair again after destructive testing until confirmation defect has been eliminated. 
(12) steel butt weld and spiral weld intersects with D-type connector where the pipe all through the X-ray television or film examination. 
(13) each pipe hydrostatic test pressure radial seal. Test pressure steel pipe pressure and time by computer testing device strictly controlled. Test parameters are automatically printed record. 
(14) pipe end machining, so that the end vertical, blunt edge bevel and accurate control.

Read more: SSAW Steel Pipe Sizes