Xenith Steel
Xenith Steel
Xenith Steel
Xenith Steel
Hydraulic cylinders don't tolerate average pipe. Bore tolerance of 0.005\" vs standard pipe's 0.020\" decides whether seals last 5000 hours or 500. That difference comes from the cold-draw process: DOM tubing pulls the OD through a die at 15-25% reduction, aligning grain structure and squeezing the ERW weld seam to under 0.1mm — functionally invisible at the ID. For ASTM A513 Type 5 DOM in 4130 alloy, yield strength reaches 75 ksi after cold work, but through-wall hardness variation of 10-15% means the softer ID layer must be honed 0.5-1.5mm for cylinder barrels. Surface finish matters as much as dimensions: Ra ≤ 0.4μm for 3000+ PSI service vs Ra ≤ 0.8μm for standard, because every micron of roughness accelerates seal wear by roughly 15%. Xenith Steel supplies DOM, seamless, and ERW mechanical tubing from Cangzhou mills with 100% ECT per ASTM A1016, straightness ≤ 1mm/m, and MTC 3.1 traceability.

Welded Steel Pipe

Seamless Steel Pipe

OCTG

Structural Steel Section

Stainless Steel Pipe

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Steel Metal

Pipe Fittings

Special Products

DOM tube for hydraulics
Cold drawing process
Mechanical pipe cut lengths

Mechanical Steel Pipe

Square

From 0.500” to 2.500”

Rectangle

From 1.000” x 0.500” to 4.000” x 2.000”

Round

From 0.125” OD to 26.000” OD

Custom Shapes (Must be large quantities)

  • Products details
  • Tolerance table
  • Chemical composition
  • Specification

Mechanical Tubing Sizes

Square

From 0.500" to 2.500"

Rectangle

From 1.000" x 0.500" to 4.000" x 2.000"

Round

From 0.125" OD to 26.000" OD

Custom Shapes (Must be large quantities)


Hydraulic Steel Tubing

  • Seamless (SAE J-524)
  • Welded (SAE J-525)

Main material:
Lining: stainless steel, duplex steel, nickel base alloys, titanium, copper and other corrosion resistant alloys.
Product Features:
Using patented technology to make two kinds of interference materials, to ensure the working state of the medium in the corrosive environment, to meet the pressure requirements, greatly reducing the cost of materials, and at the same time has a great binding force

  • Packing & Delivery
  • Chemical composition

Chemical Composition of Mechanical Steel Pipe

Chemistry

%

Carbon

0.06 - 0.018 Max

Manganese

0.30 - 0.60

Phosphorus

0.040 Max

Sulfur

0.050 Max

  • Tolerance table

Mechanical Properties

Yield
(PSI)

Tensile
(PSI)

Hardness
(Max HRB)

Elongation
(in 2" Min)

25,000

45,000

65

35%

  • Process

Seamless hydraulic tubing is produced as a seamless tube by rolling and piercing bar stock.  It then gets multiple cold-drawing reductions before a final cold draw guarantees tight dimensional tolerances and excellent surface finish.  After final sizing of the tube through cold drawing it undergoes intermediate annealing and a dead-soft annealing process to meet SAE J524 requirements.


Welded hydraulic tubing is made from flat-rolled steel shaped into a tubular form where the edges are joined and fused together by electric-resistance welding.  After forming and welding, the tubing is then normalized and subjected to a cold-drawing operation.  Following cold working, the tubing is then normalized via an atmospherically controlled method to produce a finished product that will meet requirement of SAE J525.

  • Tests

Test Requirements of Mechanical Steel Tube

  • Eddy Current Test
  • Ultrasonic Testing
  • Hydrostatic Tests
  • Metalography Test
  • MP / DP / RF ECT Testing
  • BHN Hardness & Rockwell Testers
  • Visual Inspection, TPP and CVN Impact Testing
  • Packing & Delivery
  • Tolerance table

Chemical Composition of Mechanical Steel Pipe

Chemistry

%

Carbon

0.06 - 0.018 Max

Manganese

0.30 - 0.60

Phosphorus

0.040 Max

Sulfur

0.050 Max

  • Chemical composition

Mechanical Properties

Yield
(PSI)

Tensile
(PSI)

Hardness
(Max HRB)

Elongation
(in 2" Min)

25,000

45,000

65

35%

Frequently Asked Questions

1. Why is cold-drawn (DOM) better than as-welded ERW for mechanical applications?

It's about dimensional stability and surface:
Cold-drawing process:
(1) Draws tube through die — reduces OD to exact tolerance
(2) Work-hardens the steel — surface becomes harder
(3) Squeezes weld seam shut — virtually invisible at ID
(4) Improves straightness — critical for hydraulic cylinders
Result:
DOM surface hardness: 10-15% higher than as-welded
DOM tolerances: ±0.005" vs ±0.020" for ERW
For hydraulic cylinders: DOM mandatory.

2. What surface roughness (Ra) do I need for hydraulic cylinder barrels?

Hydraulic cylinder bore surface requirements:
Ra ≤ 0.8μm: Standard service (2000-3000 PSI)
Ra ≤ 0.4μm: High-pressure (3000-5000 PSI)
Ra ≤ 0.2μm: Ultra-high pressure (5000+ PSI)
Why roughness matters:
Higher Ra = faster seal wear = leakage
Chrome-plated barrels: Ra measured after plating
Calculation: Sealing surface × pressure = leak rate
Xenith Steel supplies honed and chrome-ready finishes.

3. How does cold work affect the steel hardness?

Cold drawing increases hardness — but unevenly:
Strain hardening mechanism:
(1) Surface stretches more than ID → harder surface
(2) ID softens less → potential galling if not honed
(3) Through-wall hardness variation = 10-15%
For critical applications:
ID honing removes soft zone + creates oil reservoir.
Honing depth: 0.5-1.5mm removal.
After honing: Ra ≤ 0.4μm achievable.

4. What residual stress problems can occur in mechanical tubing?

Residual stress from cold drawing:
Types:
(1) Axial — causes bending when cut
(2) Circumferential — causes ovality when machined
(3) Through-thickness — causes distortions
Impact:
>(1) Cutting releases stress — tube bends ±3mm/m
>(2) Welding causes distortion
>(3) Machined surfaces go out-of-round
Solution:
Stress relieve at 600-650°C for 1hr/inch.
Xenith Steel offers stress-relieved material.

5. How straight does DOM tubing need to be?

Straightness affects cylinder performance:
ASTM A513: ≤3mm/m for standard
Hydraulic cylinder: ≤1mm/m required
Measurement: Roll the tube on a surface plate
Use indicator at center + 1m intervals
Maximum deviation: 1mm per meter
Correction:
Press straightening or roller straightening
Xenith Steel guarantees ≤1mm/m on request.

6. What's the weld seam remnant in DOM tubing?

The hidden truth about DOM:
The weld is still there at the ID — just drawn very thin:
Original weld: ~1mm thick
After 20% reduction: ~0.1mm
Invisible to eye, but detectable:
(1) ECT (eddy current) at ID surface
(2) Section and etch for verification
For pressure applications:
Specify ID ECT testing to verify no remnant.
For critical hydraulic (5000+ PSI):
Use seamless or specify full weld removal.