Stop Hydrocarbon Liquids and Gases Escaping 12W Pipestoppers Heat Resistant Covers Inflatable Stoppers Rubber PetroChem Stoppers are for line pipe applications. Each Stopper has a longer length than diameter, which prevents them from tipping over inside the pipe and losing their seal. They also have a ribbing to prevent slipping. Commonly used for stopping off pipes particularly where access is difficult. They are frequently used for testing new pipes and drains.