Metallurgical properties of the material
Longitudinal submerged arc welded pipes are produced from steel plates, while spiral welded pipes are produced from hot-rolled coils. The hot-rolled strip unit rolling process has a number of advantages and has the metallurgical process capability to obtain the production of high quality pipe line steel. For example, the output stand is equipped with a water cooling system to accelerate cooling, which allows the use of low-alloy compositions to achieve special strength grades and low-temperature toughness, thereby improving the weldability of the steel. However, this system is largely absent in steel sheet production plants. The alloy content (carbon equivalent) of coils is often lower than that of similar grades of steel plates, which also improves the weldability of spiral welded pipes.
More important to note is that, because the spiral welded pipe coil rolling direction is not perpendicular to the direction of the steel pipe axis (its pinch solution depends on the spiral angle of the steel pipe), while the straight seam steel pipe steel plate rolling direction perpendicular to the direction of the steel pipe axis, and thus, the spiral welded pipe material is better than the straight seam steel pipe crack resistance.
From the welding process, spiral welded pipe and straight seam steel pipe welding method is the same, but the straight seam welded pipe will inevitably have a lot of ding weld, so the chances of welding defects are greatly increased, and the residual stress of welding at the ding weld is larger, the weld metal is often in a three-way stress state, increasing the possibility of cracking.
Moreover, according to the submerged arc welding process, each weld should be at the arc initiation and arc extinguishing, but each straight seam welded pipe in the welded annular seam, can not achieve the condition, thus there may be more welding defects at the arc extinguishing.
Chemical composition table
|Mechanical properties||Chemical composition|
|Yield strength||Tensile strength||Elongation||C||Si||Mn||S||P|
|MPa||kg/mm²||MPa||kg/mm²||min||No larger than||No larger than||No larger than|
|Q215A Q215B||215||22||335-410||34-42||31||0.09-0.15||0.03||0.25-0.55||0.050 0.045||0.045|
|Commodity||Construction ASTM A106 A36 A53 Spiral Welded Black Steel Tube carbon steel spiral welded tube pipe|
|Grade||GR.B, ST52, ST42, ST35, ST45, X42, X52, X56, X60, X70, X85|
|Standard||ASTM A53, ASTM A500; GB/T3091, GB/T3094; DIN EN10025; DIN EN10217-2005;
BS EN10217; BS EN10219; BS EN10025; JIS G3466
|Technique||ERW, Welded, Seamless, Hot Rolled, Cold Drawn|
|OD||Size 8"to 142"Outside Diameter 219mm to 3620mm|
|Thickness||1.5mm - 30mm|
|Length||1) Single Random Length and double Random Length.
2) SRL:3M-5.8M DRL:10-11.8M or As clients requested length.
3) Fixed length(5.8m,6m,12m)
|Pipe Ends||1)Plain 2)Beveled 3)Threaded with coupling and plastic cap|
|End protector||1) Plastic cap 2) Iron protector 3) as request|
|Surface Treatment||1) black paint 2) varnish 3) oil or galvanized
4) anti-corrosion coated(3PE / 3LPE)
|Package||Loose package,bundled pipe with two slings at the both end for easy loading and discharging,End with Plastic caps.|
|Export To||Singapore, Canada, Indonesia, Korea, USA, UK, Thailand,Saudi Arabia, Vietnam,India, Peru, Ukraine ,Brazil,South Africa, etc.|
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