Our fittings, screwed connections and valves are equipped with Whitworth pipe threads. Dimensions are given in inches, however they do not correspond to the diameter of the thread. In comparison: 25,4 mm is equal to 1 inch, but an outer diameter of 1 inch has a bigger diameter, in this case 33,25 mm. The historical data for standardization in inch, were based on the inner pipe diameter, the wall thicknesses were much bigger. Due to new materials, their properties and further knowledge, the outer diameter was left and the inner diameter varies. Inner and outer diameter do not, comply with the actual inch data. In many cases, the Whitworth thread is indicated as BSP thread.
When using plastic piping systems, a distinction is made between tapered and cylindrical designs of the Whititworth thread.
In order to realize metallically sealed joints, a cylindrical female thread (Rp) and a conical male thread (R) are combined. In case of plastic fittings we would strongly recommend not to tighten with hemp, as this will lead to an increased diameter and the fitting will burst. We would recommend to use teflon tape from a brand manufacturer.
Cylindrical threaded fittings named G are not metallically sealed. In this case you need flat seals or O-rings, as their sealing surfaces are tapered or flat.
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