The process of connecting a new line or branch to tướng existing line by means of cutting and welding new T shaped pipe spool with a valve on the hydrocarbon process line is called as a tie-in of pipelines.
Hazards of Tie-in:
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Presence of combustible gases inside or outside of the pipe.
Fire and burn injuries.
Erection and shifting on heavy spool and valve.
Scaffolding collapse if working on height.
All hot work-related hazards.
Safety Procedure for Tie-in jobs:
Line isolation by putting blinds on flanges, line breaking and disconnecting from the process.
Approved blind list signed by the plant operator.
Risk assessment with the permit shall be taken and blind list number should be maintained on permit.
Initially line has to tướng purge with steam or air, depending on type and size of the line for some time period for release of combustible gases from the pipe.
If required or line has not clear, nitrogen shall be used for purging as an inert gas.
Do the gas test using multi gas monitor to tướng ensure LEL reading.
Once a line is clear start job with cold cutting.
Again kiểm tra for LEL and if required insert plug or balloon inside the pipe to tướng avoid any sudden gas flow from the pipe.
Take the hot work permit for hot work and follow all necessary hot work precautions for job.
Monitor the gas continuously.
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Job supervisor and safety shall be available full time.
LEL value for cold work- 10% and for hot works- 1% preferably zero.