The hallmark production process of LSAW steel pipe is longitudinal submerged arc welding. After the tube billets are butt-jointed, the longitudinal seam of the pipe body is welded using a submerged arc welding process. This involves welding the wire beneath a layer of flux, welding the inner and outer seams together to form a continuous, dense weld. The greatest advantage of this process is the minimal weld defects. This is due to the high current, deep weld penetration, and high weld strength achieved during welding, as well as the ability to isolate the weld from the atmosphere, resulting in exceptional weld quality. Is the LSAW steel pipe production complete upon completion? Of course not. Post-processing is required, including normalizing and tempering to eliminate weld stresses and improve the weld microstructure, thereby enhancing the pipe's toughness and corrosion resistance. Furthermore, quality inspection is mandatory, with 100% flaw detection of the weld seam and pipe body to detect defects such as cracks, incomplete penetration, and porosity.
LSAW steel pipe is primarily used in high-pressure, large-diameter applications. This is directly related to its forming and welding processes. Because the longitudinal weld is parallel to the pipe axis, the direction of force applied aligns with the weld, resulting in superior tensile and bending resistance compared to other welded pipes. During production, wall thickness can be determined based on actual user requirements, ranging from 20 to 60 mm, allowing it to withstand higher pressures and external loads. LSAW steel pipe is available in a wide range of diameters, from DN400 to DN3000. Furthermore, production maintains strict requirements for roundness and straightness, minimizing installation errors during pipe butt-jointing. More importantly, the welds undergo rigorous flaw detection and heat treatment, ensuring strong corrosion and fatigue resistance. With a service life of 30-50 years, it is suitable for complex environments such as underground and underwater installation, reducing future maintenance costs.
For users, being able to assess the quality of LSAW steel pipe is a crucial skill. Many users only inspect the exterior to see if the outer diameter, wall thickness, and length meet requirements, and to see if there are any cracks, pits, rust, or coating defects on the surface. However, these inspections alone are insufficient. Mechanical testing and weld inspection are essential. Of course, professional manufacturers perform nondestructive testing on all products before they leave the factory, ensuring they can be put into use directly after purchase.
We all know that LSAW steel pipe offers significant performance advantages, but users are unsure whether to choose it in many applications due to its high production costs, which translates to a higher price. Blindly choosing this type of pipe can also lead to a waste of resources. Therefore, we've summarized the appropriate use cases for LSAW steel pipe:
Preferred Applications: For large diameters, high pressures, and high loads, LSAW steel pipe is a good choice. For oil, gas, or high-temperature fluids, where durability and safety requirements are extremely high, LSAW steel pipe is also an option. Not recommended scenarios: At this time, we have to consider the cost issue. If it is a small or medium caliber and low-pressure environment, we do not recommend choosing it. For example, some community water supply pipes and small drainage networks, it would be a bit wasteful to choose LSAW steel pipes.
