New Flowstopping System For Large-Diameter, Low-Pressure Gas Mains

A new system for gas-free working on large-diameter, low-pressure natural gas mains using semi-supported flowstop bags was approved by National Grid Gas in the United Kingdom. The technique provides an easy-to-use and cost-effective alternative to squeeze-off on polyethylene (PE) mains and Iris Stop on metallic mains for maintenance, repair and modification of distribution networks while preserving continuity of supply.