Angus Bowie, Regional Director for the Middle East & Asia Pacific at STATS Group, explains how the pipeline industry has turned a corner when it comes to utilising hot tap isolation.
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hen STATS first investigated hot tap isolation back in 2005, it was discovered that the existing technology was based on equipment which had not changed since the 1950s and did not meet current standards. There was a single high-pressure lip seal with an acceptable leak-rate, an open vent and a low pressure gas bag to hopefully divert the lip-seal leak to the open vent. STATS had secured a project in the North Sea which required leak-tight double isolation of 32 × 10 in. pipes within the platform
utility shafts. With current technology, this would have required 64 full bore hot taps, 32 reduced bore gas bag hot taps and 96 vent and purge penetrations. Additionally, no existing supplier could be confident in providing a leak-tight seal in the ageing pipework with poor internal conditions and the presence of scale. At that time STATS was supplying mechanical isolation plugs with dual, full pressure, compression seals with a 98% leak-tight seal record. Where leak-tight seals could not be achieved during installation, our seal monitoring capability identified any leakrate. These leak rates were miniscule and could be vented with a ¼ in. vent hose. However, in most cases simply un-setting and relocating the isolation plug would rectify the issue before retesting the seals and issuing an isolation certificate. The seal barriers are both tested upon installation to the full pipe differential pressure and provide isolation at least equivalent to that of a double block and bleed valve. STATS utilised the Tecno Plug® sealing technology, with its extensive track record, to develop a hot tap deployed isolation tool capable of providing the safe isolation required to isolate the 32 pipes and minimise the number of hot taps required. This led STATS to develop the patented BISEP® (Branch Installed Self-Energised Plug) which was deployed through a single
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