ASTM A671 straight seam steel pipe, designed specifically for medium-high temperature and high-pressure applications, uses CC65 grade electrofusion welded structural steel as its base material and is formed through submerged arc welding. It possesses excellent mechanical properties and creep resistance. The chemical composition of straight seam steel pipe contains ≤0.24% carbon and 0.70%–1.35% manganese. Combined with a rigorous heat treatment process, straight seam steel pipe maintains a yield strength ≥345MPa and a tensile strength ≥485MPa even at 300℃. It is widely used in long-distance pipelines and process pipelines in the oil, natural gas, and chemical industries.

To withstand complex corrosive environments, straight seam steel pipe employs the DIN30678 standard 3PP (three-layer polypropylene) anti-corrosion process. The bottom layer is fusion-bonded epoxy powder (FBE, thickness ≥80μm), providing strong adhesion to the steel pipe substrate; the middle layer is a copolymer adhesive (170-250μm), facilitating the transition between the epoxy and polypropylene layers; the outer layer is high-density polypropylene (HDPE, thickness 2.5-3.7mm), possessing excellent resistance to chemical corrosion, UV radiation, and mechanical impact. Verified by DIN30678 standard salt spray testing, the 3PP anti-corrosion layer has a service life exceeding 30 years in marine environments, far surpassing traditional 3PE anti-corrosion systems.

For the end sealing requirements of straight seam steel pipes, we provide beveled steel pipe caps. These caps are made from CC65 steel plate of the same material as the steel pipe, stamped and formed. The ends are machined with a 30°±5° bevel according to ASTM A671 straight seam steel pipe requirements, with a bevel surface roughness ≤Ra6.3μm, ensuring sufficient fusion during welding with the steel pipe fittings. The inner wall of the steel pipe cap is sandblasted to Sa2.5 grade and coated with weldable anti-rust paint to prevent corrosion during transportation and storage.

Automated production lines and online testing equipment enable end-to-end quality control from steel pipe forming and 3PP anti-corrosion to steel pipe cap processing. The products have passed API 5L and ISO 21809-1 certifications, providing "zero-leakage, long-life" pipeline solutions for global energy transmission projects.