According to VBG 50, stopping-off gas pipes with a nominal diameter of > DN 150 and an operating pressure of > 30 mbar requires the use of two bags and release of the pressure between bags.

The double bag positioning system from städtler + beck was developed as alternative to setting four individual stop-off bags.

This system allows positioning and controlling of two bags in sequential order with only one bag positioning device or one set of positioning struts. Each bags features its own air inlet. In this way, both bags can be filled independently. Any damage of the pressure-side bag does not automatically affect the second bag. This technique requires only drilling and consequential sealing of one insertion hole on each side of the working space without sacrificing the security of two stop-off bags. A third injection device allows releasing the pressure of the space between both bags. Gas leaking into this space is released via a hose leading to the street level.

The bag positioning device consists of an insert with a valve for filling and releasing pressure, three bag positioning pipes (DIN 80 -125, DN 125 -200 and DN 250 - 300) with extended bag positioning shoe and one set of positioning struts with 2 pressure gauges and ball valves for filling and releasing the pressure of both bags. All components are made of galvanized steel.

Optionally, the set is also available in stainless steel.

Please use out comprehensive operating manual with maintenance instructions.