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Precision Seamless Steel Tubes

Product Overview

Precision seamless steel tubes are produced through cold drawing or cold rolling processes, eliminating longitudinal welds. This manufacturing route delivers uniform structural integrity, isotropic mechanical properties, and high resistance to internal pressure.
Unlike standard hot-rolled tubes, precision tubes offer tight dimensional control on outer diameter (OD), inner diameter (ID), and wall thickness (WT), directly reducing machining allowances and processing time for component manufacturers.

Specifications

Parameter	Technical Standard / Range
Manufacturing Standards	EN 10305-1 (DIN 2391), ASTM A519, JIS G3445, GB/T 3639
Steel Grades	E355 (+C/+SR/+N), E235, ST52, 20#, 45#, 4140 (SCM440), 20CrMo
Size Range	OD: 10 mm - 200 mm; WT: 1 mm - 20 mm
Delivery Conditions (Heat Treatment)	Cold drawn/hard (+C), Cold drawn/soft (+LC), Stress relieved (+SR), Annealed (+A), Normalized (+N)
Length Options	Fixed length 3 m - 12 m, Random length, or cut-to-length per drawing
Surface Finish	Inside and outside smooth, free of scale; phosphated and oiled, or bright annealed

Material & Manufacturing

Production Process Flow
• Raw Material Inspection: High-frequency testing of hot-rolled round billets for internal defects and chemical composition verification.
• Piercing & Hot Rolling: Rotary piercing of billets into seamless hollow mother tubes.
• Surface Preparation: Acid pickling and phosphating/saponification to remove scale and apply a stable lubricant coating for cold working.
• Cold Drawing / Cold Rolling: Multi-pass drawing on cold-drawing benches or pilger rolling to achieve target dimensions and grain refinement.
• Controlled Heat Treatment: Protective atmosphere annealing or stress-relieving furnaces to eliminate residual stress and adjust yield/tensile strength.
• Straightening & Cutting: Multi-roll straightening machines ensure straightness within ≤ 1 mm/m, followed by precise sawing/cutting to ordered lengths.

Manufacturing Capabilities
• Equipment: 150-ton and 300-ton cold drawing benches, precision cold pilger mills, roller hearth bright annealing furnaces.
• Capacity: Monthly output of 3,000 metric tons; size changeover tooling available for rapid production scheduling.

Quality Inspection

Every production lot undergoes rigorous metallurgical and dimensional testing prior to dispatch:

Dimensional Verification:

Laser OD/ID micrometers and multi-point wall thickness ultrasonic gauges measure tolerances continuously across the entire tube length.

Non-Destructive Testing (NDT):

100% eddy current testing for longitudinal defects and surface discontinuities per ASTM E309 / EN 10246-3.

Mechanical Testing:

Tensile testing (yield strength, tensile strength, elongation), ring expanding test, and flattening test per ISO 6892-1.

Metallographic Analysis:

Grain size determination, decarburization layer depth measurement, and inclusion rating.

Traceability:

Heat numbers hard-stamped or ink-jetted on each tube, mapped to mill test certificates (EN 10204 3.1).

Applications

Hydraulic & Pneumatic Systems: Honed or roller-burnished tubes utilized as cylinder barrels for construction machinery, injection molding presses, and lifting equipment.

Automotive Industry: Propeller shaft tubes, steering columns, fuel rail components, and shock absorber cylinders.

General Mechanical Engineering: Roller bearings, bushing sleeves, high-pressure fluid lines, and machined structural parts.

Customization & Supply

Custom Tolerances: Tighter ISO tolerance classes (e.g., H8, H9 for bore-finished tubes) available upon request.

Special Lengths: Exact cut lengths with deburred and chamfered ends.

Packaging Protection: Plastic caps fitted on both ends, bundled with steel strips, wrapped in moisture-resistant woven plastic, or packed in wooden crates for export shipments.

Logistics: Direct container loading from factory warehouse; flexible MOQ terms for standard steel grades and regular sizes.

FAQ

Q: What is the difference between EN 10305-1 E355+C and E355+SR?

A: E355+C (cold drawn/hard) has high yield and tensile strength due to cold work hardening, but lower elongation, suitable for structural parts requiring no further forming. E355+SR (stress relieved) undergoes thermal treatment after drawing to relieve internal stresses, offering balanced mechanical properties and dimensional stability during subsequent machining.

Q: What are your standard delivery tolerances for OD and WT?

A: Standard cold-drawn tubes are produced to EN 10305-1 tolerances (typically ±0.08 mm to ±0.15 mm depending on diameter). Closer tolerances can be agreed upon prior to order confirmation based on specific application requirements.

Q: Can you supply tubes with internal honing or roller burnishing for hydraulic cylinders?

A: Yes. We supply as-drawn tubes as well as pre-machined, honed, or roller-burnished tubes with surface roughness Ra ≤ 0.4 μm ready for immediate piston assembly.

Q: What anti-corrosion protection is applied during shipping?

A: Tubes are coated with a protective layer of rust-preventive oil on internal and external surfaces. For sea freight, tubes are wrapped in waterproof plastic film and bundled securely to prevent transit corrosion and mechanical damage.

Q: What is your standard lead time for production orders?

A: Standard sizes in stock ship within 7 - 10 days. Made-to-order production runs typically require 25 - 35 days depending on steel grade availability, quantity, and required heat treatment condition.

Q: What documentation is provided with each shipment?

A: Each shipment includes a commercial invoice, packing list, bill of lading, and a certified Material Test Certificate (MTC) conforming to EN 10204 3.1 detailing chemical composition, mechanical test results, and NDT inspection confirmation.

Request a Quote

Submit your specification requirements or engineering drawings to receive a technical quotation within 24 hours.
Required Information: Steel grade, outer diameter (OD), inner diameter or wall thickness (WT), delivery condition, quantity, and destination port.
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