4.3. Double Block and Bleed
Note: In British Columbia, double block and bleed is not permitted for confined space entries if the
adjacent piping contains a harmful substance that is a liquid of sufficient volatility to
produce a hazardous concentration of an air contaminant or is a gas or a vapor.
There are two approved methods for achieving double block and bleed:
1. Double block and bleed system.
2. Use of a single double isolation and bleed valve.
When used, double block and bleed must use valves immediately upstream of the work area.
Close the identified isolation valve(s) and open the identified bleed‐off valve(s), ensuring that
the bleed valves are not plugged or frozen.
POSITIVE ISOLATION
Rev Date: March 2015
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