Carbon Steel Precision Seamless Tube — Factory Direct Supplier | Huaxia-Steel

Huaxia-Steel supplies carbon steel precision seamless tube for hydraulic cylinders, pneumatic systems, automotive parts, mechanical structures, and instrumentation. Our tubes are cold drawn or cold rolled to tight dimensional tolerances, bright annealed or stress-relieved, and supplied with smooth internal and external surfaces. We can deliver honed ID, chrome-plated OD, and cut-to-length pieces to match your machining and assembly schedule.

Product Overview

Precision seamless tube differs from standard pressure pipe in its dimensional accuracy, surface quality, and mechanical-property control. It is produced by piercing a solid billet and then cold drawing to the final size, giving a uniform wall thickness and a smooth bore ideal for honing. The most common standards are DIN 2391, EN 10305-1, ASTM A519, and JIS G 3445.

Specifications

Parameter	Range
OD range	6 mm – 150 mm
Wall thickness	0.5 mm – 25 mm
Length	Random length 4–7 m; fixed length ±1 mm on request
Tolerance class	DIN 2391 D3/D4, EN 10305-1, ASTM A519
OD tolerance	±0.05 mm to ±0.30 mm depending on size and standard
Wall tolerance	±0.10 mm to ±0.30 mm
ID roughness (honed)	Ra 0.2–0.4 μm
Straightness	1:1000 or better on request

Available Steel Grades

• ST37.4 / E235 / St 35: Low-carbon precision tube for bending, flaring, and general hydraulic systems.
• ST44.4 / E255 / St 45: Medium-carbon grade with higher strength for cylinders and machine parts.
• ST52.4 / E355 / St 52: High-strength precision tube for high-pressure hydraulic cylinders and honed barrels.
• SAE 1020 / 1026: ASTM A519 grades for machining and structural mechanical tubing.
• SAE 4130 / 4140: Alloy grades for high-strength thin-wall tubes and aircraft-quality applications.

Manufacturing Standards

Our precision seamless tubes are produced to DIN 2391 (cold-drawn seamless precision steel tubes), EN 10305-1 (precision steel tubes for mechanical and automotive engineering), ASTM A519 (seamless carbon and alloy steel mechanical tubing), and JIS G 3445 (mechanical tubes). Certificates are issued to EN 10204 3.1 and can include actual tensile values, chemical analysis, and dimensional reports.

Applications

• Hydraulic and pneumatic cylinder barrels
• Shock absorber and damper tubes
• Automotive steering and suspension components
• Precision mechanical structures and sleeves
• Bearing races and bushings
• Heat exchanger and instrumentation tubing
• Injection-molding machine tie bars

Quality Assurance

Each heat is tested for tensile strength, yield strength, elongation, and hardness. Dimensional checks cover OD, wall thickness, concentricity, and straightness. Optional tests include eddy-current testing, ultrasonic testing, hydrostatic testing, and macroetch inspection. For honed tubes, we provide surface-roughness reports and bore-diameter measurements.

Packing and Shipping

Tubes are bundled with steel strapping, capped or plugged at both ends, and wrapped in oiled paper and plastic film. Wooden box packing is available for small-diameter or precision-finish tubes. Each bundle is tagged with grade, heat number, dimensions, and weight. We also supply loading photos and packing lists before shipment.