This appraisal is for a range of S-Gate valves in sizes DN 100, DN 150, DN 200, DN 250,DN 300, DN 375 and DN 450 with PN16 pressure classification to enable under-pressure installation of a gate valve into an existing pipeline without interruption to the water supply. This Issue 4 is to amend the PN rating of DN 300, DN 375 and DN 450 to PN16 based on additional type testing to demonstrate compliance. Issue 3 was to include advice of an update to meet AS/NZS 4020:2018 requirements.
The product consists of a ductile iron clamp with a flanged outlet that is installed onto the pipe using a bolting arrangement. An elastomeric gasket provides a leak proof seal.
A custom-designed cutting machine is fitted to the flanged outlet to provide a circumferential slot into the pipe wall whilst the pipeline is under pressure. A temporary slide valve is used to allow the cutting machine to be removed and a specially designed valve bonnet and gate to be fitted to the outlet flange. The temporary valve can then be opened and the gate inserted into the pipeline to provide a line stoppage. The gate valve then remains permanently in the pipeline as a fully functioning gate valve.