Technical Information

Standards and Specifications

General tube and pipe information and specifications.


The difference between Pipes and Tubes




Pipes are used to carry fluids and gases i.e. pipe lines, process plants etc.


Tubes are used for frames or structures i.e. chairs, gates, airport buildings, shopping centers, machinery etc.
Pipes are referenced by their approximate internal diameter. This is important for pipes as the internal diameter is critical to calculate flow rate of the pipe. It is important to note that the internal dimensions vary with different wall thickness and therefore the internal dimensions are “nominal” or averaged. Nominal bore may go by different names, in inch system it is abbreviated as NB (Nominal Bore), in metric systems DN (Diametric Nominal) or in North America NPS (Nominal Pipe Size).


Tubes are referenced by their external dimensions.

An example of a commonly confused size between pipes and tubes

50 NB Schd 80 Pipe – The actual outside diameter is 60.3mm, the wall thickness is 5.49mm and its internal diameter is 49.32mm, close to its nominal size of 50 NB/ 0.8mm diameter nominal.


50.8mm X 5mm – The actual outside diameter is 50.8mm , the wall thickness is 5mm and its internal diameter is 40.8mm.



Interested to see case studies/examples of uses of steel tubes/pipes and how they can be used to save money versus other products? Please visit the American steel tube institute.


While every effort is made to ensure accuracy, no representation is made as to the accuracy of, and no acceptance or any legal responsibility is taken for any errors, omissions or mistakes.

How tubes are measured

Circular Tube

eg. 127 x 4.5 x 6
diameter (mm) x wall thickness (mm) x length (M)

Square Tube

eg. 200 x 200 x 8 x 6
width (mm) x breadth (mm) x wall thickness (mm) x length (M)

Rectangular Tube

eg. 300 x 100 x 10 x 6
width (mm) x breadth (mm) x wall thickness (mm) x length (M)

Bunton Tube

eg. 300 x 100 x 10 x 6
width (mm) x breadth (mm) x wall thickness (mm) x length (M)

How pipes are measured

Circular Pipe

eg. 200NB Shed40 x 6
or 200DN x 8.18 x 6
or 8”NPS Shed40 x 6
nominal diameter (mm) x wall thickness (mm) x length (M)

Get in touch with us

If you have any question, Please don’t hesitate to send us a message.


Please do not send enquiries for any of the below mentioned points, we will not respond as we cannot assist

We only sell steel tubes & pipes.
X We do not sell flanges, pipe fittings, steel bars, beams, plates or any other steel sections.
X We provide no manufacturing or fabrication services other than cutting to size steel tubes or pipes.
X We do not provide the service of reading through tender documents and drawing up a bill of materials/ quantities.
X We do not stock stainless steel tubes and pipes.
We only supply sub-Saharan Africa namely South Africa, Namibia, Lesotho, eSwatini, Botswana, Mozambique, Zimbabwe, Zambia, Democratic republic of Congo, Malawi, Angola, Kenya, Tanzania, Madagascar, Mauritius etc. etc.

    When requesting a quotation, please do not forget the following important information-
    1. The quantity
    2. The size
    3. The wall thickness
    4. Length of tube/ pipe
    5. Steel grade
    6. If available, the manufacturing standard



    265 Main Reef Road,
    Knights, Germiston,
    EXT 3, 1401,
    South Africa