Pipe & Tube Manufacturing Process

Cold finished（hard）Pipe&Tube

Cold Finished (hard) Steel Pipes (BK/+C) represent a delivery state where steel tubes undergo cold forming processes without subsequent heat treatment. Confirm the material standard and acceptance requirements before ordering.

Custom grades & dimensionsFull quality traceabilityGlobal standards support

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Product details

Product Description

The manufacturing process involves cold drawing or cold rolling operations conducted entirely at room temperature, followed by basic finishing steps including straightening, end cutting, and surface cleaning. This simplified production workflow eliminates heat treatment stages, resulting in shorter lead times and reduced manufacturing costs while preserving the benefits of cold working.

These BK condition pipes exhibit exceptional mechanical strength and hardness due to work hardening during cold processing. The enhanced strength properties significantly surpass those of annealed (GBK) and normalized (NBK) tubes, though with reduced plasticity and toughness typically showing elongation rates between 10%-15% depending on material grade. The precise dimensional control achieved through cold working ensures tight outer diameter and wall thickness tolerances with excellent surface finish and low roughness values.

The superior surface quality of Cold Finished Steel Pipes presents clean, smooth surfaces free from oxide scale, requiring no additional polishing or surface treatment. However, the presence of residual internal stresses from cold working necessitates careful consideration for applications involving bending, welding, or complex forming operations, where preliminary annealing may be required to prevent cracking or deformation.

Technical Characteristics:

• High strength and hardness through work hardening

• Tight dimensional tolerances with excellent surface finish

• Simplified manufacturing process without heat treatment

• Immediate availability for assembly and basic machining

• Cost-effective production with shorter lead times

• Suitable for applications without complex secondary forming

Cold Finished Steel Pipes serve effectively in mechanical manufacturing for precision shafts, fasteners, and structural components where high stiffness and dimensional accuracy are paramount. These hard-condition tubes are widely used in hydraulic and pneumatic systems for short-stroke cylinders and pipe connectors requiring high strength without bending operations. The precision instrument industry utilizes these pipes for housings and drive shafts benefiting from their high precision and rigidity, while general engineering applications favor them for direct assembly situations where complex forming is unnecessary.

Supported by Tenjan’s 21 years of seamless tube expertise and 30 years of technical experience in our R&D team, we provide customized cold finished solutions tailored to your specific application requirements. Our advanced manufacturing capabilities ensure each Cold Finished Steel Pipe (BK/+C) meets exact specifications for materials, dimensions, surface quality, and mechanical properties, delivering reliable performance for your engineering applications where high strength and precision are essential.

Seamless Steel Tubes for Industrial Applications

Custom Sizes OD10-108mm-ASTM/EN/DIN/JIS/GOST Certified -Small-Batch Friendly

Technical data

Product Specifications

Parameter	Key Features
Outer Diameter	10-108mm (0.39″-4.25″) • Fully customizable
Wall Thickness	1-20mm (0.039″-0.79″) • ±0.1mm precision tolerance
Material	Carbon Steel • Alloy Steel • Special grades available
Process	Cold Drawn Cold Rolled for superior finish

Available materials

Shaped Seamless Steel Tube&Pipe - Steel Grade Availability

Standard	Typical Grades We Supply
GB	DT4,Y15,10#,20#,20G,Q235,25Mn,35#,45#,55# 16Mn,Q345B(Q355B),Q345C(Q355C),Q345D(Q355D),Q345E(Q355E),Q420,Q460,20Cr,40Cr, 15CrMo,20CrMo,30CrMo,35CrMo,42CrMo,20CrNiMo,40CrNiMo,20CrMnTi,20Mn2,40Mn2,40MnB,35MnB, 35Mn15CrMn,20CrMn,20CrMnMo,38CrMoAL,36Mn2V,38Mn2V,40MnMoV,15Mo3,16Mo3,31CrMoV9
ASTM	1215,1008,1010,1020,A105,A106 Gr.B,A36,1026,1035,1045,1055,SA179,SA192 Gr·50,Gr·55,Gr·65,5120,5140,4130,4135,4140,8620,4340,SAE 5120,1524,1340,15B41,SAE5115,SAE 5120,SCM23
EN	DC01,11SMn30,P235TR1,P195GH,P265TR2,E235 E355,ST52,S355JR,S355JO,S355J2,S355NL,S420N,S420NL,S460NL,20Cr4, 41Cr4,13CrMo4-5,20CrMo4,25CrMo4,34CrMo4,42CrMo4,20NiCrMo2,34CrNiMo6,20MnCr5, 22Mn6,42Mn6,42MnB4,34MnB5,37Mn5,16MnCr5,20CrMo5.
JIS	SUM22,S10C,STKM11A,STPT370,STB35,S20C,STKM12,STKM13,STPT410,STB42,SS400,S35C,S45C,S55C SCr22,SCr440,SCM415,SCM420,SCM430,SCM435,SCM440, SNCM220,SNCM439,SMnC420H,SMn420,SMn438, SMnC420H
DIN	DC01,11SMn30,CK10,C10,ST35.8,C20,CK20,ST45.8,St37,S235JR,C26D,CK35,CK45,CK55
GOST	08КП,10,20,Ст3сп,25,35,45,5515Г2, 09Г2C/10Г2C1,15Г2,14Г2С,C355,20Х,40X,15XM,20ХМ,30ХМ,35ХМ,38ХМ,20ХНМ,40ХНМ,20ХГТ,20Г2,40Г2,18ХГ,20ХГМ
Other Speical Grades can be customized

Applications

Industry-Specific Solutions

Industry	Key Applications Parts	Relevant Standards	Our Advantages
General Structural	Square Rectangular Tubes	GB/T 3094,ASTM A500, EN 10210	Good Surface,lightweight,precision dimensions (±0.1mm)
Automotive and Motorcycle Component	Shock Absorbers，Steering Systems，Thrust Rods	EN 10305-1,JIS G3445, DIN 2391,ASTM A519	High fatigue strength,High yield strength,lightweight, precision dimensions (±0.1mm)
Engineering and Mining Support	Anchor Bolts,Support Pipes,Hydraulic Props	ASTM A519,DIN 2391, JIS G3441,EN 10297-1, ISO 10799	High Strength Yield Strength High Elongation Customization Service – Special steel grades, dimensions and surface treatments available according to project requirements
Construction Machinery	Drive shaft sleeves,Gearbox Guide Tubes,Crane Boom Guide Tubes,Excavator Arm Tubes,Loader Frame Tubes,Arctic Low-Temperature Tubes	ASTM A519,DIN 2391, JIS G3445,EN 10210-1, GOST 8733, ASTM A106,ISO 9329	ID/OD tolerances of ±0.05mm. Wall thickness uniformity straightness ≤0.5mm/m
Fluid Transport Systems	Oil/Gas pipelines,chemical systems,Power/Energy	ASTM A106 Gr.B, EN 10216-2,GOST 8734	Eddy Current + Ultrasonic Testing,Hydrostatic Testing
High-Pressure Boilers	Superheaters,Steam lines,Reheaters,Economizers)	ASTM A192,DIN 17175, EN 10216, JIS G3461/G3462	Enhanced material density through cold-drawing/rolling ensures long-term stability Full Compliance with Int’l Standards,Superior Creep Fatigue Resistance
Geological Drilling	Drill Pipe,Tubing	ASTM A519,API 5DP, EN 10208-2	High Strength Wear Resistance precision Dimensions Impact Fatigue Resistance
Agricultural Machinery	Hydraulic cylinders,drive shafts,Lift arms,steering housings,Boom frames	ASTM A519,EN 10210-1, DIN 2391,GOST 8733, JIS G3445	Material Advantages:High Strength Lightweight,Precision Cold-Drawing Technology,Dimensional accuracy ±0.05mm
Petroleum Cracking Units	Reformer Tubes,Heat Exchanger Tubes,Reactor Feed Pipes,Transfer Lines,Quench Oil Pipes	ASTM A335,ASTM A213, EN 10216-2	Optimized Material Purity,Precision Dimensional Control,Customized Solutions

Why choose us

Custom Advantages

Tailored Features · Designed Exclusively for Your Needs

Alloy Steel Material and Process Planning Material Sourcing Review:

For each order, confirm the material grade, dimensions and acceptance requirements:

✔ 100+ Custom Alloy Grades– Chemistry control (C, Cr, Ni, Mo adjustments)

✔ Engineered Mechanical Properties -Yield/Tensile strength customization

✔ Industrial-Grade QC-Full-spectrum testing (UT, hardness, dimensional)

✔ Project-Specific Cost Review-Compare grade, order quantity and downstream processing requirements

Application:Oil & Gas, Automotive, Heavy Machinery, Energy

Extra-Long Piercing + Automated Normalizing Furnace – Precision Alloy Steel Tubes for High-Stress Applications Heating and Delivery Condition Review:

Review billet heating and normalizing requirements for alloy steel tubes, and agree the delivery condition and acceptance criteria before production.

Normalizing Requirements to Confirm:

✔ ±2°C Precision Control–Confirm the temperature-control requirement

✔ Mechanical Property Review–Specify strength and fatigue-related acceptance requirements

✔ Batch Consistency Checks–Confirm heat and batch traceability

Key Industries Served:Oil & Gas, Power Generation, Automotive, Geological Drilling, Mining Support and Construction

Tube Straightening – Confirm Requirements Before Machining Straightness and Machining Review:

Confirm the required straightness, including the stated ≤0.5mm/m value, against the component drawing and agreed inspection method:

✔ Machining Preparation– Confirm straightness and machining allowance for the component

✔ Cutting Tool Selection – Select cutting conditions for the supplied grade and hardness

✔ Production Planning –Review material allowance, handling and scrap criteria

Production and Inspection Review:

Process Review – Confirm the production route and inspection records

Automated QC – Real-time straightness monitoring

Custom Solutions– Optimized for alloy steel grades

Key Applications: Hydraulic Cylinders, Oil & Gas, High-Performance Automotive (drive shafts, suspension components)

Ultrasonic + Eddy Current Dual Testing – High-Reliability Inspection for Alloy Steel Tubes

Advanced NDT System Features:

✔ Ultrasonic Testing (UT)– Detects internal flaws down to 0.20mm

✔ Eddy Current (ET)– Identifies surface/subsurface defects

✔ Multi-Probe Technology– Confirm ID/OD/wall coverage

Quality Assurance:

Inspection Acceptance Criteria(agree the method, reference standard and acceptance level)

Dimensional Control– ±0.05mm OD tolerance

Material Verification– Full composition check

Application Review: Oil & Gas, Energy, Automotive