Thick-walled Seamless Steel Pipe

To address this issue, we strictly control the heating curve in thick-walled pipe production. We use a medium-frequency induction heating furnace for penetration heating to ensure uniform temperature from the inside to the outside of the steel pipe. In the heat treatment stage, we extend the holding time and employ controlled cooling technology to minimize the temperature difference between the inside and outside. This seemingly inefficient practice is to ensure that the thick-walled pipes do not suffer brittle fracture due to their porous internal structure under high pressure.

In terms of materials, carbon steel and alloy steel are the mainstream materials for thick-walled pipes. 20# and 45# carbon steel thick-walled pipes are commonly used in mechanical structures, bushings, cylinder bodies, and general pressure-bearing components; they offer good machinability and controllable costs. Low-alloy high-strength steels such as Q345B (16Mn) are widely used in bridge bearings and engineering machinery structural components. In high-strength, high-wear-resistance, or high-temperature applications, alloy thick-walled pipes such as 42CrMo, 35CrMo, 15CrMo, and 12Cr1MoV begin to play a role. Among them, 42CrMo, after tempering, combines strength and toughness and is a common material for oil drill collars, hydraulic supports, and heavy-duty shafts. For some special applications, stainless steel thick-walled pipes such as 304 and 316L, or high-alloy heat-resistant steel pipes such as P91 and P92, are also used.

Manufacturing processes are a key aspect of thick-walled pipe production. Large-diameter thick-walled pipes are mostly produced using hot rolling or hot expansion processes, while some ultra-thickness and ultra-high strength specifications are formed using hot extrusion or even forging and boring. Small and medium-diameter thick-walled pipes can achieve higher dimensional accuracy and surface quality through cold drawing or cold rolling. Due to the large wall thickness, heat treatment is particularly critical – normalizing, tempering, and quenching and tempering (quenching + tempering) processes directly determine the final mechanical properties of the pipe. Ultrasonic testing (UT) is usually performed before shipment to eliminate internal defects.

As a supplier serving the global market, we have accumulated mature experience in delivery. Our factory is certified to ISO 9001 quality management system and ISO 14001 environmental management system, and can cooperate with third-party inspections such as SGS, BV, and TUV, issuing material testing reports (MTC) according to EN 10204 3.1. Standard specifications are readily available in stock and shipped within 7 business days; non-standard customized products, special heat-treated products, and large-diameter, thick-walled specifications typically take 15 to 35 days to deliver. Shipping ports include Tianjin, Qingdao, and Shanghai. We support both full container loads (FCL) and less than container loads (LCL). Trade terms are applicable to EXW, FOB, CIF, and CFR. Payment is accepted via T/T and letter of credit at sight. Export packaging uses end caps, rust-proof paper wrapping, steel strapping, or wooden crates for securing. The pipe body is printed with the material, standard, specification, and furnace batch number. Each shipment includes a commercial invoice, packing list, certificate of origin, and a complete set of quality inspection documents to ensure smooth customs clearance.