Contact Platform Support
Help CenterSteel Pipe & Tube & Precision Steel Tube，GB/T3639、GB/T32957、EN10305
Related Products
-
Steel Pipe & Tube & Cast Steel Pipe，HT150、HT200、HT250、HT300、QT400-18、QT450-10、QT500-7、QT600-3、KTH350-10、KTZ450-06、KTZ650-02NegotiableMOQ: 5 Metric Tons -
Steel Coil & Strip & Hot Rolled Steel Coil，Q235A/Q235B/Q235C/Q235D、Q390、Q420、Q460、Q550、Q690NegotiableMOQ: 5 Metric Tons
-
Steel Coil & Strip & Cold Rolled Steel Coil，GB/T 13237、GB/T 5213、JIS G3131、EN 10130NegotiableMOQ: 5 Metric Tons
-
Steel Coil & Strip & Prepainted Steel Coil，S220GD+Z、S250GD+Z、S320GD+Z、S350GD+Z、S420GD+Z、DX51D+AZ、S350GD+AZ、DX51D+ZM、S350GD+ZMNegotiableMOQ: 5 Metric Tons
-
Steel Sheet & Plate & Pressure Vessel Steel Plate，16Mo3、13CrMo4-5、10CrMo9-10、SA387 Gr11 Cl2、SA387 Gr22 Cl2（2.25Cr-1Mo）NegotiableMOQ: 5 Metric Tons
1. Product Definition & Core Overview
Precision seamless steel tube is a high-precision hollow seamless pipe manufactured by cold rolling or cold drawing after hot piercing blank forming. Different from ordinary hot-rolled seamless pipes, it adopts multi-pass cold finishing and precise heat treatment, featuring ultra-tight dimensional tolerance, ultra-smooth internal & external surface, uniform wall thickness and stable mechanical performance without internal residual stress.
The product series covers carbon steel precision tubes, alloy steel precision tubes and stainless steel precision tubes. It can be directly used for mechanical deep processing without secondary turning and grinding, widely applied in hydraulic & pneumatic systems, auto parts, engineering machinery, precision instruments, aerospace and bearing manufacturing fields, adapting to high-pressure, high-precision assembly and heavy-load mechanical service conditions.
2. Executive Standards
2.1 Chinese National Standards
GB/T 3639-2021 Cold drawn and cold rolled seamless precision steel tubes (domestic core standard)
GB/T 699 Carbon structural steel
GB/T 3077 Alloy structural steel
GB/T 8163 Seamless steel tubes for fluid transportation
GB/T 14976 Seamless stainless steel tubes
2.2 International Industrial Standards for Export
DIN 2391 Precision seamless steel tubes (German hydraulic industry standard)
EN 10305-1 / EN 10305-4 Cold finished precision steel tubes (European standard)
ASTM A519 Seamless carbon & alloy mechanical tubing
ASTM A179 Cold-drawn low-carbon heat exchanger tubes
SAE J524 Precision hydraulic tubing
JIS G3445 Carbon steel tubes for machine structure
3. Product Classification
3.1 Classification by Base Material
Carbon Steel Precision TubeGrades: 10#, 20#, 35#, 45#, Q355B (E355). Low carbon grades feature excellent ductility and weldability for hydraulic cylinders, gas springs and pipeline parts; medium carbon grades own high strength for shafts and structural components.
Alloy Steel Precision TubeGrades: 16Mn, 27SiMn, 42CrMo, 15CrMo, 35CrMo, 20MnCr5. High strength, wear-resistant and impact-resistant, suitable for high-load auto transmission parts, engineering hydraulic cylinder barrels and bearing sleeves.
Stainless Steel Precision TubeGrades: 304, 316L, 2205 duplex steel. Excellent rust & acid corrosion resistance, ultra-clean inner surface, applied in medical equipment, semiconductor, food machinery and chemical precision pipelines.
3.2 Classification by Cold Finishing Process
Cold Rolled Precision TubeHigher dimensional accuracy, smoother surface (Ra 0.2~0.8μm), thinner wall, preferred for high-end hydraulic, instrument and medical precision parts.
Cold Drawn Precision TubeWide size range, stable cost performance, suitable for medium-precision mechanical structural parts, general hydraulic pipelines and auto standard components.
3.3 Classification by Delivery Heat Treatment Status
NBK: Normalized after cold forming, good plasticity for bending, flaring and welding
GBK: Annealed after cold forming, ultra-low hardness for deep drawing and complex machining
BK: Hard cold finished without heat treatment, high surface hardness for wear-resistant parts
4. Main Steel Grades & Applicable Working Conditions
20# / E235Low carbon precision tube, good cold forming and weldability, working pressure ≤16MPa, used for hydraulic oil pipes, gas springs, auto chassis pipelines and common mechanical sleeves.
45# / CF53Medium carbon steel, high tensile strength after quenching & tempering, for mechanical transmission shafts, gear sleeves and structural bearing parts.
Q355B / E355Low alloy high strength grade, excellent low-temperature toughness, widely used in engineering machinery hydraulic cylinder barrels and heavy-load equipment frames.
27SiMnSpecial hydraulic cylinder tube material, high hardenability, stable inner hole precision after honing, the mainstream raw material for high-pressure hydraulic cylinder barrels.
42CrMoCr-Mo alloy precision tube, outstanding fatigue and impact resistance, for auto crankshaft sleeves, wind power gearbox parts and heavy machinery bearing components.
5. Dimensional Precision & Mechanical Performance Index
5.1 Dimensional Tolerance Standard
Outer Diameter Tolerance: Premium grade ±0.15%~±0.2%; standard grade ±0.3%~±0.45%
Wall Thickness Uniformity: Single tube wall thickness deviation ≤0.03mm
Straightness: ≤0.15mm per 1000mm length
Surface Roughness: Cold rolled Ra 0.2~0.8μm; cold drawn Ra 1.6~3.2μm
Inner Hole Precision: Can reach H8 / H9 / H10 tolerance band for direct honing without rough turning
5.2 Conventional Mechanical Properties
Yield Strength: 245~830MPa (varies by material & heat treatment status)
Tensile Strength: 410~1080MPa
Elongation after fracture: ≥10%~25% (annealed/normalized status)
Process performance: Fully pass flattening, flaring, 180° cold bending tests without cracks
5.3 Mandatory Factory Inspection Items
Full dimensional inspection: OD, wall thickness, length, straightness, end flatness
100% eddy current non-destructive testing to detect surface cracks, inclusions and delaminations
Hydrostatic test: Max test pressure up to 25MPa, pressure holding ≥30s without leakage
Additional tests: Spectral chemical composition analysis, hardness test, surface roughness detection, grain size inspection
6. Complete Specification Range
Outer Diameter: 6mm ~ 256mm
Wall Thickness: 0.5mm ~ 20mm, thin wall, standard wall and thick wall customizable
Standard Fixed Length: 6m per piece; customized 3m / 9m / 12m, arbitrary cutting and precise pipe end chamfering available
Appearance Quality: Smooth internal & external surfaces free of cracks, folds, scars, oxide scales and rust; flat burr-free pipe ends, uniform wall thickness without eccentricity
7. Complete Production Process Flow
Qualified seamless tube blank re-inspection → heating & hot piercing → tube blank sizing → pickling & phosphating lubrication → multi-pass cold rolling / cold drawing → stress relief heat treatment (NBK/GBK/BK status) → straightening → internal high-pressure washing & scrubbing → eddy current NDT → hydrostatic pressure test → full dimensional precision inspection → pipe end deburring & chamfering → anti-rust oil coating → plastic dust-proof end cap installation → steel belt bundling & warehousing
Special closed heat treatment furnace eliminates internal residual stress, and independent inner wall cleaning procedure removes iron filings and impurities to guarantee high cleanliness for hydraulic system service.
8. Core Product Advantages vs Ordinary Seamless Tubes
Ultra-high Dimensional Precision Tight OD, wall thickness and inner hole tolerances eliminate secondary turning & grinding, greatly reducing customer machining cost and processing cycle.
Super Smooth Internal & External Surfaces Low surface roughness without oxide skin, effectively reducing hydraulic fluid flow resistance and avoiding pipeline blockage caused by falling oxide scale.
Uniform Wall Thickness & Zero Eccentricity Stable pressure bearing capacity under high-pressure alternating load, no local stress concentration to extend service life of hydraulic cylinders and pressure pipelines.
Diversified Heat Treatment Delivery Status Multiple material hardness options available to match bending, welding, deep drawing, quenching and other different processing requirements.
Excellent High Pressure Resistance Integral seamless structure with uniform metallographic organization, suitable for hydraulic systems under long-term 16~25MPa working pressure without tube burst risk.
Full Standard Traceability Comply with domestic and international precision tube standards, complete inspection documents to support mechanical equipment export bidding and third-party acceptance.
9. Main Application Fields
Hydraulic & Pneumatic Industry High-pressure hydraulic oil pipes, honed cylinder barrels, cylinder liner blanks, pneumatic valve bodies and gas spring tubes.
Automobile & Motorcycle Manufacturing Chassis oil pipelines, transmission shaft sleeves, shock absorber tubes, engine precision structural parts and steering components.
Engineering Machinery Excavator, loader and crane hydraulic cylinder raw tubes, bearing sleeves and heavy load support tubes.
Precision Instruments & Aerospace Instrument sensing pipelines, aviation hydraulic thin-wall tubes, lightweight precision structural sleeves.
Bearing & Mechanical Processing Bearing inner sleeve blanks, gear sleeves, high-precision shaft tubes and automation equipment structural parts.
Medical, Food & Chemical Equipment 304/316L stainless steel precision tubes for medical catheters, food conveying pipelines and anti-corrosion fine chemical equipment.
10. Machining, Installation & Operation Specifications
For cold finished BK hard state tubes, annealing treatment is required before bending, welding or deep drawing to prevent cracking caused by high internal hardness.
Hydraulic system matching precision tubes shall be fully flushed before assembly to remove residual iron filings and anti-rust oil inside the tube cavity to avoid pump and valve component abrasion.
Alloy precision tubes for high-load transmission parts shall conduct quenching & tempering heat treatment after finish machining to improve surface hardness and fatigue resistance.
Stainless steel precision tubes for medical & food service shall adopt electrolytic polishing treatment to reach medical grade cleanliness, and avoid contact with corrosive medium during storage.
Long-term static pressure equipment using precision hydraulic tubes shall regularly check pipeline surface for corrosion and deformation, replace aging tubes in time.
Send Inquiry to This Supplier
You May Also Like
-
Steel Sheet & Plate & Checkered Plate，2.5、3.0、3.5、4.0、4.5、5.0、6.0、7.0、8.0、10、12、14、16mmNegotiableMOQ: 5 Metric Tons
-
Steel Sheet & Plate & Shipbuilding Steel Plate，AH32、DH32、EH32、FH32、AH36、DH36、EH36、FH36、AH40、DH40、EH40、FH40NegotiableMOQ: 5 Metric Tons
-
Steel Sheet & Plate & Boiler Steel Plate，P265GH、P355NH、16Mo3、13CrMo4-5、10CrMo9-10NegotiableMOQ: 5 Metric Tons
-
Steel Sheet & Plate & Steel Sheet Pile，S275GP、S355GP、S390GP、S430GPNegotiableMOQ: 5 Metric Tons
-
Steel Rebar & Deformed Steel Bar / Rebar，HRBF400、HRBF400E、HRBF500、HRBF500ENegotiableMOQ: 5 Metric Tons
-
Steel Wire & Galvanized Steel Wire，Q195、Q235、60、65、70、72A、40Cr、30CrMnSiNegotiableMOQ: 5 Metric Tons
-
Flat Steel & Steel Flat Bar，10#、20#、35#、45#、40Cr、42CrMo、20CrMnTiNegotiableMOQ: 5 Metric Tons
-
Steel Angle & Angle Bar，Q235B、A36、SS400、S235JR、45#、40Cr、65MnNegotiableMOQ: 5 Metric Tons
-
H Section Steel & H Beam，Q235A、Q235B、Q235C、Q235D、Q355B/C/D/E、Q390、Q420、Q460、Q235NH、Q355NH、Q345GNHNegotiableMOQ: 5 Metric Tons
-
Galvanized Flat Bar＆Flat Steel，GB/T 704, GB/T 13912, ASTM A123, JIS G3302NegotiableMOQ: 5 Metric Tons
