SSIV meaning in oil and gas

Sub Surface Isolation Valve

Also known as Sub Sea Isolation Valve - best get any engineer to explain properly what these things are. <p> <p> A Engineer speaks<p> <p> SSIVs are often installed on gas and oil export pipelines, on the sea bed perhaps some 500 metres from an offshore installation. Their purpose is to automatically close under fire emergency conditions to protect the installation from the huge inventory of oil and gas in the pipeline. <p> <p> The incident on Piper Alpha eventually culminated in a jet fire impinging on one of the export pipelines, which eventually failed with catastrophic results. At the time other platforms, many miles away, were still feeding in to the pipeline and therefore feeding the fire on Piper Alpha