Hazards
Spill of (hazardous) material can occur when a barrier (like a valve) fails and no second barrier is in place.
When Important
During routine and special operations: draining & sampling, (un-)loading activities, utility connections.
Challenges in the Field
- Older plant design often do not provide a double barrier.
- Blind flanges not put back after maintenance work.
- Blind flanges not installed with bolts & missing end-caps.
- Importance of “primary containment” not understood.
- Valve handles that can be opened accidentally.
Options to Get it Right
- Do not rely on a single valve for positive isolation.
- Execute regular audits to check that drains are having an end-cap (blind flange or screw cap) conform pipe-spec.
- Do not accept missing blind flanges or missing bolts on blind flanges.
- Report and investigate all incidents from leaking drains.
- Valve handles can be locked to avoid accidentally opening.
This page only summarises the guidance – refer to the EPSC website for further information.
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