Where pipe ends of different outside diameters have to be connected, stepped couplings can be provided.These normally cover the difference between the outside diameters of pipes of different materials of construction with a common nominal bore, or pipes of the same materials having different nominal bores.
It is advisable to mark the pipe a known distance from the end when fitting a step coupling to enable inspection of movement. This will allow the inspector to ensure that no telescoping along the smaller diameter pipe has occurred.
When this fitting is used as a coupling between two pipes with diameter differences exceeding 25mm it is essential to ensure that the stepped coupling cannot be forced along the smaller diameter pipe. Scheduled sizes will not normally require such precautions, but others may. Regular inspection of a pipe previously marked, is normally all that is required. Alternatively, where this cannot be arranged, a mechanical means should be employed.
Pressure rating for stepped couplings are equivalent to the rating specified in the straight coupling schedules, for the larger of the two OD's. In the case of ductile iron, AC and uPVC pipes, the pressure rating will match the pipe rating.
Vortex Stepped Couplings can be manufactured with full sleeves to prevent end pullout on PE, HDPE and GRP pipes.
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