Hot-finished seamless steel pipes are structural pipe products for mechanical engineering, construction, energy, and petrochemical industries. Manufactured by hot rolling continuously cast billets on pipe rolling mills. Steel grades: St20 (general purpose, tensile strength ≥410 MPa), 09G2S (increased strength σв ≥490 MPa, frost resistance down to −60°C), 13KhFA (for oil pipelines). Diameter 32–426 mm, wall thickness 2.5–40 mm. GOST 8731-74 (technical specifications), GOST 8732-78 (assortment). Testing: hydrostatic test, ultrasonic testing, mechanical tests. Applications: pipelines, frames, supports, casing pipes, boiler units, machine parts. Coating: uncoated (black), VUS insulation (for underground), anti-corrosion paint. St20 pipes — working pressure up to 16 MPa (∅57, wall 5 mm). 09G2S — for Arctic conditions: impact toughness KCV ≥34 J/cm² at −60°C. Length: measured (6/12 m) or unmeasured (5–12 m). Supply: bundles, strapped with tape. Ends: plain or beveled. Documentation: certificate 3.1 EN 10204, hydrostatic test report.