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Disconnect Line Requirement

Disconnect Line Requirement

Sep 19, 2020

Disconnect line requirement

Without regard to the completed inspection and the instrument in use, it must be assumed that dangerous conditions would arise in the disconnected position if the line were disconnected.

It must be specified by a qualified engineer or based on factory specific procedures. A supervisor must be present when a line containing hazardous substances is disconnected.

This must be performed by a trained person with experience in plant mechanical integrity.


The nearest safety spray should be marked. If the distance is more than 50 feet, or the reach time is more than 10 seconds, a portable sprinkler or water spray should be available for emergency use.

The factory must clearly mark or physically identify the method in the disconnection program where the disconnection occurs.

Work areas and surrounding areas have been cordoned off and warning signs have been placed

All personal protective equipment is available

All energy sources that could affect work have been released and controlled;


Turn off/off all pumps and are locked and Tagout

All valves are switched to the defined safe position and are locked and listed

All blind plates have been installed correctly

Identify all connections and their locking tags

Close all connected tracing pipes and lock the Tagout

All residual pressure has been released correctly

Disconnect line requirement

All lines have been emptied and flushed and/or emptied as required. A written record is required to ensure that "clean" indicates the absence of any other hazards. Note: when high temperature steam is used to purge the pipe before work to remove residual flammable substances, violent decomposition reactions of substances with poor thermal stability may occur. Disposal of residue should follow local pollution control policies and practices.