A large-diameter longitudinally welded pipe is a general term. It is produced by a steel strip. The pipes that are welded by high-frequency welding equipment are called longitudinally welded pipes. (The name is given because the welds of the steel pipe are in a straight line). Among them, according to different purposes, there are different back-end production processes. (Roughly divided into scaffolding pipe, fluid pipe, wire casing, bracket pipe, guardrail pipe, etc.)

Generally, straight seam steel pipes with a diameter above 325 are called large-diameter steel pipes. The welding process of large-diameter thick-walled longitudinal seam steel pipe is double-sided submerged arc welding technology, and manual welding can also be carried out after the steel pipe is formed. The general inspection method is flaw detection. After the flaw detection is qualified, it can be delivered. Substandard products need to be welded again. Large-diameter thick-walled straight seam steel pipes are generally suitable for the transportation of fluids, support of steel structures, and piling. They are widely used in petrochemical, construction, water engineering, power industry, agricultural irrigation, urban construction, etc. The steel pipe should be able to withstand the internal pressure, and carry out the 2.5Mpa pressure test, and keep it without leakage for one minute. The method of eddy current flaw detection is allowed to replace the hydraulic test. The molding methods mainly include UOE, RBE, JCOE, etc., among which JCOE has a high usage rate. The pipe end can also be threaded according to customer requirements, also called threaded and unthreaded.

The production process of large diameter straight seam steel pipe:

The production process of large-diameter straight seam steel pipes generally includes production methods such as hot rolling, hot coiling, and casting. Large-diameter thick-walled steel pipes generally use double-sided submerged arc welding production processes. The products are bent, welded, internally welded, and externally processed. Welding, straightening, flat heading, and other processes meet the requirements of petrochemical standards.

The use of large-diameter straight seam steel pipes is mainly used for body supporting parts, such as bridge piling, subsea piling, and high-rise building piling.

The materials used for large-diameter straight seam steel pipes are generally Q345B and Q345C. Q345D is also used in areas with low temperatures. Q345E large-diameter straight seam steel pipes are mostly used in large-scale steel structure construction.