Welded steel pipes are the pipes that surface has the steel pipe joint, which is use the steel belt or steel plate material through the bending deformation into round ,square ect then welded into shape. Welded steel pipe products are widely used in boilers, automobiles, ship building lightweight structural steel of the doors and windows, furniture, agricultural machinery, scaffolding, wire conduit, top shelves, containers, etc.. which can meet customer requirements, the special specifications welded steel pipe can be processed according to user requirements. Welded pipes for conveying water, sewage, gas, air, heating, steam and other low-pressure fluid and other uses. According to different weld methods can be divided into electric arc welding tube, the high frequency or low frequency electric resistance welded steel pipe and gas welding tube, furnace welding pipe , bondi pipe, etc.
- Electric Resistance Welded steel pipe used in oil drilling and machinery manufacturing, etc.
- Furnace tube welded steel pipe can be used for water gas pipe, etc.
- Longitudinal Submerge-arc Welded used for high pressure straight oil and gas transportation etc.
- Spiral welded steel pipe used for the oil and gas transmission, and pipe pile etc.
Welded steel pipes for pressure applications
- at room temperature according to EN 10217-1 in materials P 235 TR1 or TR2
- at high temperatures according to EN 10217-2- and -5 in material P235 GH/TC1
- according to EN 10217-3 in material P355 N
- according to API 5L in materials Grade B PSL 1 and Grade BM PSL2
- according to API 5L in materials Grade X52 PSL 1 and Grade X52M PSL2
- according to ASTM A53-1995 in material Type E Grade B
Welded steel pipes for steel construction
- Welded steel pipes according to EN 10219-1 and 2 in materials S 235 JRH, S 275 JOH, S 355 JOH and S 355 J2H
Welded steel pipes for water transport
- Welded steel pipes according to EN 10224 (DIN 2460)
Welded steel pipes for flammable media
- Welded pipes according to EN 10208 (DIN 2470)
Welded steel pipe dimensions:
- Outer Diameter: 6mm-4064mm
- Wall Thickness: 0.3mm-50mm
- Length: 6mtr-18mtr
Difference between ERW, SSAW, LSAW
Steel pipe for pipe technology, can be divided into (SML), mainly as the Oilfield internal transportation pipeline and small-diameter high-pressure natural gas pipeline, used for a small number of long-distance gas pipeline, the vast majority of long-distance pipeline with Direct seam high frequency (ERW), spiral submerged arc (SSAW), LSAW three (LSAW).
The following table several steel pipes process characteristics and quality of performance comparison:
ERW pipes means Electric Resistance Welded Pipes. ERW steel pipes and tubes are used.
High frequency straight seam welding (ERW) method is divided into two forms of induction welding and contact welding, hot-rolled wide volume as raw material, pre-curved, continuous molding, welding, heat treatment, sizing, straightening, cutting, etc. process, compared with the spiral weld short, high dimensional accuracy, uniform thickness, surface quality, pressure advantages, but the drawback is that only the production of small and medium-caliber thin-walled tube, weld easy to produce gray leaf spot, not fusion ditch-like corrosion defects. Wider application areas of city gas, crude oil transportation.
Spiral submerged-arc welded pipes
Spiral submerged arc welding(SSAW) is its forward direction and forming tube centerline hose reel molding angle (adjustable), side molding edge welding and weld them into a spiral.
Spiral submerged arc (SSAW) is its forward direction and forming tube centerline hose reel molding angle (adjustable), side molding edge welding and weld them into a spiral, the advantage of the same specification to produce a variety of diameter sizes steel pipe, raw materials to adapt to a wider range, the weld can avoid the main stress force better, the disadvantage is the poor geometry of the weld length compared to the long straight seam pipe, prone to cracking, porosity, slag, welding partial welding defects such as welding stress was tensile stress state. General Oil and Gas Pipeline design specification spiral submerged arc can only be used for Class 3, Class 4 regional. Raw materials instead will this process improvement abroad steel plate forming and welding separate pre-weld and lean and, after welding cold flaring near UOE pipe welding quality, currently no such process of plant improvement direction. “West-East” still is a traditional craft production, just expanded diameter of the pipe end. United States, Japan and Germany, the overall negative SSAW, think the mainline unfit for use SSAW; Canada and Italy part SSAW Russian small amount of SSAW, and have developed a very strict supplementary conditions, due to historical reasons, the majority of the domestic main trunk or use SSAW.
Longitudinally Submerged Arc Welded Steel pipes
In High Frequency Induction (HFI) Welded Pipe production process, hot rolled steel coils are fed with a high capacity accumulator in order to achieve continuous welding. LSAW (LSAW) in leaflets plate as raw material, the steel plate in the mold or molding machine pressure (volume) into using double-sided submerged arc welding and flaring from production. A wide range of the finished product specifications, weld toughness, ductility, uniformity and dense, with a large diameter, wall thickness, high pressure resistance, low-temperature corrosion resistance, etc.. Required steel pipe in the construction of high-strength, high toughness, high-quality long-distance oil and gas pipelines, mostly large diameter thick wall LSAW.
API standard provisions, in the large-scale oil and gas pipelines, when 1, Class 2 areas through the alpine zone, the bottom of the sea, the city densely populated area, LSAW only applied specifically casts. Molding can be divided into:
- UOE: leaflets steel plate after the edge preflex, after U molding, O forming within welding, the outer welding, mechanical cold expanded diameter process;
- JCOE: Press “JCOE” pre-welding, forming, welding after cold expanded diameter process;
- HME: “CCO” forming mandrel rolling method, after the welding process by the cold expanded diameter.
Steel surface treatment is mainly anti rust, the following is anti rust process: First step is to clean, use cleaning solvent emulsion cleaning the steel surface, in order to achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove the steel surface rust, oxide, solder medicine.