API 5L Welded Steel Line Pipe

After the production line is set up, we will utilize it to manufacture large-diameter submerged API 5L Welded Steel Line Pipe. Initially, we will conduct ultrasonic inspection on the entire plate. Subsequently, the edges of the steel plate will undergo double-sided milling through an edge milling machine to achieve the desired plate width, edge parallelism, and groove shape. Then, we'll utilize prebending machine equipment to pre-bend the plate edges, ensuring they possess the required curvature. Following this, half of the pre-bent steel sheet will be pressed into a J-shape through multiple steps using a JCO forming machine. Concurrently, the other half will be stepped and pressed into a C-shape, ultimately forming an open O-shape.

The formed straight seam welded steel pipe undergoes welding, employing gas-shielded welding for continuous welding. Longitudinal multi-wire submerged arc welding is performed on the interior of the straight steel pipe, while the exterior undergoes the same process for straight seam submerged arc welding steel pipe. Upon completion of welding, consecutive inspections including the first ultrasonic inspection, the first X-ray inspection, diameter expansion, and a water pressure test will be conducted.

The high-frequency welding process is rooted in the principles of electromagnetic induction, as well as the skin effect of alternating current in conductors, vortex heat flux effect, and proximity effect. The edge steel of the weld is heated until it reaches a molten state, and then the roller extrusion process is employed to achieve intergranular fusion of the butt weld, thus fulfilling the purpose of welding. High-frequency welding falls under the category of induction welding and can also be referred to as pressure base welding. It does not require filler material for the weld and produces no welding splatter during the welding process. The area affected by welding heat is narrow, resulting in elegant welding molding and excellent mechanical properties. Due to these advantages, high-frequency welding is extensively utilized in the production of steel pipes

The high-frequency welding process for steel pipes leverages the skin effect and proximity effect of alternating current. Following rolling, the API 5L Welded Steel Line Pipe is shaped into a round tube blank with a discontinuous cross-section. Inside this tube blank, near the center of the induction coil, one or a set of inductors rotate, creating an electromagnetic induction circuit with the open end of the tube blank. Due to the skin effect and proximity effect, a strong and concentrated thermal effect is generated at the edge of the tube blank's opening, rapidly heating the weld edge to the temperature necessary for welding. After extrusion by the pressure rolls, the molten metal achieves indirect crystalline bonding, cooling to form a solid butt weld.

As the professional manufacture, we would like to provide you Pengfa API 5L Longitudinal Welded Steel Pipe. Straight steel pipe English (Straightsteel pipe), general welded pipe: general welded pipe is used to transport low-pressure fluid. Made of Q195, Q215A, Q235A steel, Q235B plain carbon. It can also be manufactured together with easy-to-weld 0317 standard model 6012 and steel mother 755 mild steel. Steel pipes are subject to water pressure, bending, flattening and other tests, and have certain requirements for surface quality. Usually, the delivery length is 4-10m, and it is often required to deliver in fixed length (or double length).

 The specification of the API 5L Welded Steel Line Pipe is indicated by the nominal diameter (mm or inch). The nominal diameter is different from the actual one. The welded pipe has two types of ordinary steel pipe and thickened steel pipe according to the specified wall thickness. The welding process of submerged arc welding straight seam steel pipe is submerged arc welding technology, which uses filler welding and particle protection flux submerged arc. The diameter of production can reach 1500mm. LSAW is the English abbreviation of submerged arc welding straight seam steel pipe. The production technology of submerged arc welding straight seam steel pipe includes JCOE forming technology and rolling forming submerged arc welding technology. 

When dealing with large diameters, two steel plates may be employed for rolling, resulting in the presence of double welds. Applicable standards include GB/T3091-2008 standards for the production of low-pressure fluid steel pipes, GB/T9711.1-2-1997 standards for the production and utilization of oil and gas steel pipes, as well as the American API 5L Welded Steel Line Pipe execution standards. The production materials utilized are Q195A-Q345E, 245R, Q345QA-D, L245-L485, and X42-X70. The pressure parameters primarily consist of 2ST/T, where S represents the yield strength and T represents the wall thickness. Submerged arc welding has evolved into two-wire and multi-wire submerged arc welding, further enhancing its efficiency.

Product Parameter (Specification)

Product Feature And Application

According to the production process, API 5L Welded Steel Line Pipe can be divided into high frequency straight seam steel pipes and submerged arc welded straight seam steel pipes. Straight seam steel pipes are mainly used in water supply engineering, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, and urban construction.

Used for liquid transportation: water supply and drainage.

For gas transportation: gas, steam, liquefied petroleum gas.

For structural purposes: as piling pipes, as bridges; pipes for wharves, roads, building structures, etc.

Product Details