For pressure testing and stopping all pipework from 50 mm (2 They are manufactured with > 1 / > 2 " , 1 > " , 2 > " outlets as shown in the chart overleaf.The standard seals are made from natural rubber although special rubber seals are available for improved chemical resistance and higher temperature applications.All plugs conform to British Standards BS 8005 for low pressure testing and sealing of pipes. > " ) upwards. To complete the Pipestoppers range of nylon expanding plugs, aluminium plugs, steel drain plugs and inflatable stoppers, we offer double steel plugs for increased stability and higher pressure duties. The test pressure capability of the single stoppers is limited and the double versions increase that capability, while offering a greater stability in the pipe.As single plugs approach their pressure limits, they can tend to tip over like a butterfly valve. The double plugs will prevent the tipping and guarantee the seal. >