Product Specification

STKM 13A Carbon Steel Seamless Precision Tube (Thick-Walled) for Mechanical Engineering

Material

STKM 13A is a JIS-grade carbon steel tube designed for machine-structural and general mechanical parts. As a seamless precision tube, it is commonly produced by hot-finished seamless tubing followed by cold working (e.g., cold drawing) to achieve improved dimensional accuracy, surface finish, and consistency—especially important for thick-walled load-bearing components and machining-intensive parts.

Typical chemical design intent for STKM 13A emphasizes moderate carbon content for balanced strength, ductility, weldability, and machinability.

Specifications

• Manufacturing: Seamless tube; precision sizing commonly achieved by cold working (cold drawing / cold rolling) depending on required tolerance and surface quality.

• Typical supply range (customizable):

  • Outside Diameter (OD): 4–380 mm

  • Wall Thickness (WT): 0.5–25 mm

  • Length: 3,000–12,000 mm (random/fixed length by agreement)

• Dimensional tolerance (example reference):

  • OD tolerance: ±0.5 mm when OD < 50 mm; ±1% when OD ≥ 50 mm

  • WT tolerance: +0.6 / −0.5 mm when WT < 4 mm; +15% / −12.5% when WT ≥ 4 mm

• Delivery conditions (available by request, typical for precision tubes): +C / +LC / +SR / +A / +N

Main Features

• Thick-wall strength reserve for mechanical load, impact, and fatigue-prone parts

• Seamless structure for improved pressure capacity and uniformity versus welded tubing

• Precision-ready surfaces suitable for machining, turning, drilling, and threading

• Flexible heat-treatment options (stress-relieved / annealed / normalized) to match forming and machining needs

Our Advantages

1. “Will the tube meet tight tolerance and repeatability for CNC machining?”
   Yes. Precision tubes are commonly finished by cold drawing, a process specifically used to achieve tight dimensional tolerances and better consistency for downstream machining.

2. “Is the surface finish good enough to reduce tool wear and improve sealing performance?”
   We can supply precision tubing in controlled delivery states (e.g., +SR, +A, +N). Precision tube specifications commonly include high surface quality requirements, and for certain precision-tube deliveries the surface roughness can be controlled to micrometer-level targets (project-dependent).
   If your application is hydraulic sealing (e.g., cylinder internals), we will recommend the correct route (precision tube → honing / skiving-roller burnishing if needed) based on the required Ra.

3. “How do you verify tube integrity (NDT) and mechanical compliance?”
   We support inspection plans that include tensile testing and forming tests (flattening / flaring) where required, plus eddy current, magnetic flux leakage, or ultrasonic testing depending on the project’s risk profile and standard requirements.

4. “Can you provide traceability and Mill Test Certificates for international projects?”
   Yes. We can provide documentation packages aligned with common global trade expectations (e.g., heat/batch traceability and MTC practices widely used under EN 10204 frameworks when requested).

Chemical Composition

Mechanical Properties

Applicable Standards (Selection by System)

• JIS (Japan): JIS G 3445 (STKM grades for machine structural carbon steel tubes)

• ASTM (USA): ASTM A519 (Seamless carbon/alloy steel mechanical tubing)

• EN (Europe): EN 10305-1 (Seamless cold drawn precision tubes; E355 delivery conditions)

• GOST (Russia/CIS): GOST 1050 (Steel 20 reference grade); tubes commonly paired with relevant GOST tube standards by project requirement

• GB (China): GB/T 3639 (Seamless precision steel tubes; Grade 20)

Application Fields

Primary industries

• Mechanical engineering and general machinery

• Automotive components

• Hydraulic and pneumatic equipment

• Fabrication requiring machining-ready tubular stock

Where it is used

• Thick-walled structural sleeves and bushings (machined from tube)

• Shaft sleeves / spacers / collars, CNC-turned parts

• High-load frames and mechanical supports where uniformity is important

• Hydraulic equipment components (tube-based parts; additional finishing applied when sealing-grade ID is required)

Q: Are you trading company or manufacturer ?

A: manufacturer,also can do trading.

Q: How long is your delivery time?

A: Generally speaking,it is 10-15 days if the goods are in stock,or it is 30-40 days if the goods are not in stock,

it is according to quantity.

Q: Do you provide samples? is it free or extra ?

A: Yes, we could offer the sample for free charge but need pay the cost of freight.

Q: What is your terms of payment ?

A: Payment<=2000USD, 100% in advance. Payment>=2000USD, 30% T/T in advance ,balance before shippment.

If you have another question, pls feel free to contact with me.