Materials and Quality

Carbon Steel

Material Properties

Cold Rolled Mild Steel, Pre Galvanised and Aluminised coil is purchased - primarily from New Zealand's sole Steel producer - to stringent SPCD drawing gauge specifications that match or better similar products made internationally.

Standard Base materials currently used include:

  • Cold Rolled Mild Steel gauges between:
    0.80mm and 2.5mm.
  • Pre Galvanised commercial grade Steel: 
    G250 Z275 and G310 Z450.
  • Aluminised Steel:
    1.6mm gauge ASTM A463, T1-40.
  • Thickness Tolerance:
    +/- 8% of specified wall thickness.
  • Surface Finish:
    Lightly oiled.

Alternative base materials can be used by special arrangement.

Full mechanical properties for all base material used is available on our Web Site, or our Product Catalogue supplied on request.

Quality Standards

Industrial Tube Manufacturing Co. Ltd takes pride in efficiently producing quality tubing on a consistent basis. This is achieved through adherence of their AS/NZC ISO 9002 accreditation, and commitment toward improved production efficiencies.

During our manufacturing process the tube is subjected to stringent testing:

  • Flare Test: Outside diameter increased by 25% or more without failure to either the base material or the weld zone.
  • Flattening Test: Capable of being flattened without cracking between two parallel planes with the weld zone located at both 90 and 0 degrees.
  • Surface examination: Visual inspection for external surface damage, straightness, twist, weld position, correct profile etc. must meet company and/or customer specification.

Stainless Steel

General Information

Specification Scope :

This specification applies to general tube and food / milk processing industry (FQ). 

Equivalent standards :

AS1528.1 - Tubes for the food Industry
ASTM A249 & A269 - Boiler, heat exchanger and condenser tubes
ASTM A554 - General & Architectural Application

Available sizes :

Tube sizes range from 6.35 mm to 203.2 mm outside diameter.

Grades of Material :

304, 304L,316, 316L Stainless Steel

Manufacture :

Automatic tig welding with no addition of filler metal

Heat treatment :

Tube is not post weld heat treated except for Standards ASTM A269 & A249 where tube is annealed

Material Tests

 GradesTP 304 TP 304L TP 316 TP 316L 
 C max0.070.03 0.08 0.03 
 Mn max2.00 2.00 2.00 2.00 
 P max0.045
 0.0450.045 0.045 
 S max0.030.03 0.03 0.03 
 Si max0.75 0.75 0.75 0.75 
Cr 17.5 -- 19.5 17.5 -- 19.5  16 -- 1816 -- 18 
Ni 8 -- 10.5 8 -- 12 10 -- 14 10 -- 14 
N max0.10 0.10 0.10 0.10 
Mo -- -- 2.00-3.00 2.00-3.00 

Mechanical Tests

Except tube made to ASTM A249 and specifically requested otherwise Yield stress , Tensile tests & Hardness Mn - Manganese tests are from coil manufactured to ASTM A240 / 480.

Yield Stress (Coil)
 TP 304 & TP 316 205 MPa min
 TP 316L & TP304L 170 MPa min

Tensile Stress (Coil)
 TP 304 & TP 316 515 MPa min
 TP 316L & TP 304L 485 MPa min

Elongation (Coil)
40% Minimum (50mm test piece)

Hardness tests (Coil)
 TP 304 & TP 304L 92 HRB / 202 HB30 max
TP 316 & TP 316L  95 HRB / 217 HB30 max

Tube Weld Integrity Tests

Reverse Bend Test :
Flatten to 2 times material thickness. 

Flare / Cone Test :
Minimum 1.21 tube diameter (60 deg included angle). 

Flange Test :
Minimum 1.10-1.15 tube diameter. 

Eddy Current Test :
All tube diameters are on-line eddy-current tested.

Tube Dimensional Tolerances

Outside diameter (OD)

 O/D ≤ 31.8 µm  ± 0.13 µm
 31.8 < O/D ≤ 76.2 µm ± 0.25 µm
101.6 < O/D ≤ 127.0µm ± 0.38 µm
152.4 < O/D ≤ 203.2µm± 0.76 µm

Ovality :
Difference between maximum and minimum diameters at any one cross section to be within max & min sizes as above. 

Thickness tolerance :
to ±0.10mm (AS 1528:1) 

Weld Bead :

Weld bead of tube without cold work controlled to 110% of wall thickness 

Straightness :
Maximum of 1.0 mm / metre

Length tolerance :
Standard length 6 metres -0 /+35 mm Cut to exact length jobs, by agreement (+/- 1 mm)


End finish :
Sizes to 203.2 deburred both ends 

Finish internal :
Tubes with diameter greater than or equal to 31.8 mm are internally cold worked (Internal weld beaded to tube surface). Tubes with diameter less than  31.8 mm are in as welded condition and internal weld height is controlled to a minimum height. 

Finish external :
Available as follows: 
  1. As welded condition (external weld bead removed).
    May have forming, straightening & weld polish cross hatch marking. 
  2. Standard Polished equivalent to 320 Grit - typical Ra = 0.5µm to 0.8 µm
    Minor form marks may be visible. 

Documentation & Packaging

Packaging :
Polished Tube is individually plastic sleeved in a bundle with steel strapped cleats and plywood for forklift plate. 

Traceability :
Controlled batch traceability from raw material to finished tube. For traceability purpose the tube is either inkjet marked or attached with label identifying sizes , batch & trace numbers. 

Test certificate :
Raw material test certificates are available on request. Certificate of Test of Finished Tube is provided for the tube dispatched under ASTM A249/ A269.