Large Diameter Seamless Steel Tube

Large diameter seamless steel pipes typically refer to pipes with an outer diameter of 219 mm or larger, and in some cases up to 1020 mm. Compared with standard-size pipes, large-diameter seamless pipes are manufactured using advanced hot rolling or hot expansion processes, which completely eliminate weld seams. This makes them the preferred material for high-pressure, high-temperature, and corrosion-resistant applications in demanding industrial environments.

Manufacturing Process

Hot Rolling
The steel billet is heated to the piercing temperature and then processed through a continuous rolling mill to reduce wall thickness and diameter. The finished product features a dense microstructure and excellent mechanical properties.

Hot Expansion
This process uses an existing seamless pipe as the base material. Through medium-frequency induction heating, the pipe is expanded on an expansion machine using a conical mandrel, enlarging a smaller pipe into a larger diameter pipe.
Hot expansion can produce ultra-large specifications that conventional rolling mills cannot manufacture, typically with an outer diameter of 325 mm-1220 mm and wall thickness up to 200 mm for non-standard sizes.

Grades of Large Diameter Seamless Stainless Steel Pipes

TP304/L/H, S30400, S30403, S31409

TP316/L/H, S31600, S31603, S31609

TP310S/H, S31008, S31009

TP321/H, S32100, S32109

TP347/H, S34700, S34709

904/L, etc.

Technical Specifications of Large Diameter Seamless Steel Pipes

Core Advantages of Large Diameter Seamless Stainless Steel Pipes

1. Excellent Pressure Resistance
   The seamless structure ensures uniform stress distribution when subjected to internal pressure or external forces. Its pressure resistance is significantly higher than that of welded pipes of the same size, making it critical for high-pressure oil and gas transmission.

2. High Material Purity
   Manufactured from high-quality round steel through piercing, the pipe has a uniform internal structure, providing excellent impact toughness and fatigue resistance.

3. Precise Dimensional Control
   Through subsequent sizing and straightening processes, the pipes meet the high precision requirements needed for large engineering pipeline connections.

4. Corrosion Resistance and Long Service Life
   Combined with various anti-corrosion coatings, these pipes can maintain a service life of several decades in complex environments such as underground or subsea installations.

Application Scenarios of Seamless Stainless Steel Pipes

• Oil and Gas Industry
  Used for long-distance oil and gas pipelines, furnace tubes in petroleum cracking units, geological drilling casings, and drill pipes.

• Energy and Power Generation
  Used for manufacturing high-pressure boilers, supercritical boiler superheater tubes, water wall tubes, and main steam pipelines in nuclear power equipment.

• Petrochemical and Chemical Industry
  Widely used in refinery heat exchanger piping, process thermal pipeline networks, and high-pressure pipelines for fertilizer equipment.

• Infrastructure and Construction
  Used as main pipelines for municipal water supply and drainage, bridge support structures, load-bearing columns in high-rise buildings, and pile foundations for ports and docks.

• Heavy Machinery and Equipment
  Applied in the manufacture of large hydraulic cylinder barrels, mining machinery supports, and shipbuilding structures.

Product Standards

Large diameter seamless steel pipes are typically produced according to international or national standards, such as:

ASTM A106 — Seamless carbon steel pipe for high-temperature service

ASTM A53 — Pipe for structural and fluid transport applications

API 5L — Pipeline steel pipe for oil and gas transportation

GB/T 8163 — Seamless steel pipes for fluid transportation

GB/T 8162 — Seamless steel pipes for structural purposes

Weight Calculation Formula for Seamless Steel Pipes

(OD−WT)×WT×0.02466=kg/m

Where:

OD = Outer Diameter (mm)

WT = Wall Thickness (mm)

Packaging

• Wooden Cases
  Used for packaging large diameter mirror-finish stainless steel welded pipes or tubes.

• Standard Bundled Packaging
  Large diameter stainless steel welded pipes/tubes (non-mirror finish) are usually packed in bundles.

• Wooden cases and pallet packaging are also available. Other packaging methods can be customized according to customer requirements.