The Metal Company stock a range of OD (outside diameter) and ID (inside diameter) tube. So what’s the difference? 

Dairy Tube, General Purpose Tube and Metric Press-fit Tube is measured and named according to the outside diameter of the tube, which includes the wall thickness. For example, a 6” Piece of dairy tube measures exactly 6 inches or 152.4mm across from the outside of the wall to the opposite outside wall. This is the standard way to measure all the tube and tube fittings we stock, from ¼” right up to 8”.

In New Zealand, Spiral Welded Tube is measured according to the Internal Diameter. This is from the internal of one wall to the opposing wall, inside the tube and excluding the wall thickness. For example, this means an 8” piece of Spiral Weld Tube measures exactly 8” or 203.2mm across the internal diameter of the tube. We stock fittings that suit internally measured Spiral Weld for 8”, 10” and 12” sizes.

At 8”, The Metal Company stock fittings to fit both OD Measured Tube and ID Measured Spiral Weld Tube. This means it’s important to know the correct measurements for the system you are working with to ensure you get the right fittings.