Steel Pipes – Comprehensive Guide

In modern infrastructure and industrial systems, steel pipes are the most easily underestimated yet indispensable core material. From the crisscrossing underground water and gas pipelines in cities to the high-pressure transmission pipelines deep in oil and gas fields, from the load-bearing steel structures of cross-sea bridges to the precision-controlled hydraulic cylinders in mining machinery, steel pipes, with their unique advantage of hollow cross-sections, simultaneously bear multiple functions such as fluid transportation, structural support, and heat exchange.

Steel pipes are steel materials with hollow cross sections and a length much greater than their diameter. They are mainly divided into two categories: seamless steel pipes and welded steel pipes. They can also be further subdivided according to material, cross-sectional shape, and application. They are an economical steel material that can reduce structural weight and save 20% to 40% of metal.

The mainstream hot-rolling process is round billet → heating → piercing → multi-pass rolling → sizing → cooling → straightening → flaw detection and warehousing. Cold rolling/cold drawing processes are used for small-diameter precision pipes, requiring multiple drawing operations and intermediate annealing to eliminate work hardening.

Made from sheet and strip, after cold bending, the joints are welded using high-frequency resistance welding or submerged arc welding. Subsequent sizing, hydrostatic testing, and non-destructive testing complete the finished product.

Q235B / Q195

Ordinary carbon steel, easy to weld, low cost; used for scaffolding, guardrails, low-pressure water supply, ordinary structural welded pipes, and galvanized pipe base materials.

20# High-Quality Carbon Steel

Excellent plasticity, toughness, and weldability; seamless fluid pipes, boiler tubes, hydraulic pipelines, and ambient temperature industrial conveying.

Q355B/D/E (formerly Q345) Low-Alloy High-Strength Steel

30% higher strength than Q235, excellent low-temperature toughness; used for high-pressure pipelines, bridges, low-temperature environments, and thick-walled pipes for engineering machinery.

15CrMoG, 12Cr1MoVG High-Pressure Boiler Alloy Tubes; used in power plant superheaters and petrochemical high-temperature pyrolysis pipelines, withstanding temperatures above 500℃.

Naturally corrosion resistant, uncoated; suitable for food and pharmaceutical applications, seawater desalination, chemical acid and alkali media transportation, and pure water transport; standard ASTM A312.

Seamless Structural Pipes: GB/T8162
Seamless Fluid Transport Pipes: GB/T8163
Low-Pressure Welded Pipes/Galvanized Pipes: GB/T3091
Buried 3PE Anti-Corrosion Pipes: GB/T23257
Spiral Welded Pipes: GB/T9711

API 5L: Oil and Gas Transmission Pipelines (SSAW/LSAW/Seamless Universal), graded into Gr.B, X42, X52, X60, and X70 steel grades; core standard for long-distance oil and gas pipelines;
ASTM A106 Gr.B: High-Temperature Seamless Carbon Steel Pipes; used in power plants and refineries;
ASTM A53: Black Pipes, Galvanized Welded Pipes; used for low-pressure fluids;
ASTM A312: 304/316 Stainless Steel Pipes.

EN 10216 Seamless pressure steel pipes, EN 10217 Welded pressure steel pipes, EN 10210 Structural hollow pipes.

ISO 3183 Oil and gas transmission steel pipes, with technical specifications compatible with API 5L, universally accepted in global tenders.

Pipe Type	Pressure Grade	Diameter Range	Core Advantages	Typical Application Scenarios
Seamless Pipe	High Pressure & High Temperature	DN6~DN300	Weld-free, fatigue resistant	Boilers, high-pressure chemical pipelines, hydraulics, oil well casings
ERW Straight Welded Pipe	Medium-Low Pressure	DN15~DN600	Low cost, fast delivery	Fire protection, water supply, scaffolding, civil fluid transport
SSAW Spiral Welded Pipe	Medium-Low Pressure, Large Diameter	DN219~DN3000	Ultra-large diameter, single long length, pile foundation dedicated	Municipal pipe networks, oil & gas branch lines, bridge pipe piles
Hot-Dip Galvanized Pipe	Indoor Low Pressure	DN15~DN200	Atmospheric anti-rust, easy installation	Fire protection, indoor gas pipelines, HVAC systems
3PE Anti-Corrosion Pipe	Buried Medium-High Pressure	DN200+	30+ years underground corrosion resistance	Buried urban gas & water supply main pipelines
PU Thermal Insulated Pipe	High-Temperature Thermal Heating	DN100~DN1400	Heat insulation for direct buried heating	Central heating systems, industrial hot water delivery
Plastic Lined Pipe	Neutral Fluid & Drinking Water	DN50~DN1200	Smooth non-scaling inner surface, non-toxic	Tap water supply, neutral chemical media delivery

Long-distance oil and gas pipelines: API 5L LSAW straight seam submerged arc welded pipe, large-diameter spiral pipe;
Oilfield gathering and transmission branch lines: 3PE anti-corrosion spiral pipe, FBE seamless pipe;
Power plant boilers, high-temperature heat exchangers: 20#, 15CrMoG high-pressure seamless steel pipe.

Urban main water supply: 3PE spiral steel pipe, cement mortar lined welded pipe;
Residential heating direct burial: polyurethane insulated steel pipe;
Fire protection systems: hot-dip galvanized straight seam welded pipe;
Sewage/chemical wastewater discharge: internally and externally coated anti-corrosion steel pipe.

Acid and alkali media, pure water, food fluids: 304/316 stainless steel seamless pipe, epoxy coated pipe.

Bridge pile foundations, factory columns, wind power foundations, wharf cofferdams: large-diameter spiral welded pipe, Q355 thick-walled straight seam pipe.

Hydraulic cylinders, precision bushings, equipment oil circuits: Cold-drawn precision seamless 20# steel pipe.

Construction site scaffolding: 48mm Q235 straight seam black pipe / galvanized pipe.

We supply full range steel pipes: seamless pipe, ERW straight welded pipe, SSAW spiral pipe, hot-dip galvanized pipe, 3PE anti-corrosion pipe, PU thermal insulation pipe and EP coated pipe. Our products comply with GB, API 5L, ASTM, EN standards with complete MTC test reports, ISO9001 & API certification.