Pipeline block valves should be used to limit the release of line contents in case of leaks or pipeline ruptures outside plant boundaries : These valves are called “sectionalising block valves”.
Sectionalizing Valve (SV) are installed at regular intervals (around 25 to 40 Kms.) to isolate pipeline section during emergencies like leakage in pipeline as per statutory requirements. An SV station is installed at such locations having a unmanned control room with a guard room and boundary wall.
A lockable grill cage is provided over the Sectionalizing Valve installation including piping and instrumentation to prevent tampering by unauthorized persons and ensuring safety of pipeline operations.
1. Onshore : Not withstanding the ANSI/ASME requirements (Article 434.15.2/846.11) the spacing of sectionalising block valves should consider limiting the pipeline liquid contents between adjacent valves.
2. Offshore : There is no requirement for sectionalising block valves in offshore pipelines.