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20MM~508MM Outer Diameter Q235 Black 20# 45# 16mn Large Diameter Spiral Welded Steel Pipe
| Product name | Q235 Black 20# 45# 16Mn Large Diameter Spiral Welded Steel Pipe | ||||||
| Material | 10#, 20#, 45#, 16Mn, A53(A,B), Q235, Q345, Q195, Q215, St37, St42, St37-2, St35.4, St52.4, ST35 | ||||||
| Wall thickness | 1MM~12MM | ||||||
| Outer Diameter | 20MM~508MM | ||||||
| Physical Property | API 5L, ASTM A53-2007, ASTM A671-2006, ASTM A252-1998, ASTM A450-1996, ASME B36.10M-2004, ASTM A523-1996, BS 1387, BS EN10296, BS 6323, BS 6363, BS EN10219, GB/T 3091-2001, GB/T 13793-1992, GB/T9711 | ||||||
| Grade | 10#-45#, 16Mn, A53-A369, Q195-Q345, ST35-ST52 Grade A, Grade B, Grade C | ||||||
| Surface Treatment | 1. Galvanized 2. Black 3. Transparent oil,anti-rust oil | ||||||
| Pipe Ends | Plain end/Beveled,protected by plastic caps on both ends, cut quare,grooved,threaded and coupling,etc. | ||||||
| Application | Suitable for fire piping system,air,gas,oil and so on | ||||||
Inspection process
Raw material inspection -- leveling inspection -- butt welding inspection -- molding inspection -- internal welding inspection -- external welding inspection -- pipe cutting inspection -- ultrasonic inspection -- groove inspection -- external dimension inspection -- X-ray inspection -- hydraulic test -- final inspection
In order to ensure the quality of products, we have developed a complete quality plan, on-site work procedures and inspection, test plans.
Spiral welded pipe and straight seam welded pipe technical characteristics do a simple comparison:
Metallurgical properties of materials
Straight seam submerged arc welded pipe is made of steel plate, while spiral welded pipe is made of hot rolled coil. Hot strip mill rolling process has a series of advantages, it has the metallurgical process ability to produce high quality pipeline steel. For example, a water cooling system installed on the output bench to speed cooling allows the use of low alloy composition to achieve special strength grades and low temperature toughness, thus improving the weldability of the steel. But this system is largely absent in steel mills. The alloy content (carbon equivalent) of coil plates is often lower than that of similar grade steel plates, which also improves the weldability of spiral welded tubes.
More importantly, because the rolling direction of spiral welded pipe is not perpendicular to the axis of steel pipe (its clamping depends on the spiral Angle of steel pipe), and the rolling direction of straight seam steel pipe is perpendicular to the axis of steel pipe, the anti-cracking performance of spiral welded pipe material is better than that of straight seam steel pipe.
Welding process
From the welding process, the spiral welded pipe and straight seam steel pipe welding method is consistent, but the straight seam welded pipe will inevitably have a lot of t-shaped weld, so the probability of weld defects is also greatly improved, and the t-shaped seam welding residual stress is larger, the stress state of the weld metal are often in a three-way increases the possibility of a crack.
Moreover, according to the technological provisions of submerged arc welding, every weld should have arc initiation and arc extinguishing, but each straight seam welded pipe cannot meet this condition when welding around the seam, so there may be more welding defects at the arc extinguishing.
