Every valve has a potential leak possibility basically. Once leakage happens, fluid leaks to downstream.
But if BOXY blind valve leaks, fluid never pass to downstream.
Typical valve cannot gaurantee leakage trouble to down stream
Process shall be stopped and residue needs to be drained between valves for maintenance.
When 1st valve leaks, fluid reaches to 2nd valve and there is a leakage possibility to downstream.
To avoid leakage to downstream, bleed line shall be always open to drain out continuous leaking fluid.
BOXY 100% gaurantee perfect isolation
Even though Butterfly valve leaks and fluids(or gas) reaches to BOXY blind valve, it never go over downstream.
Before operating BOXY blind valve, internal pressure of BOXY product shall be depressurized and drain residue between block valve and BOXY blind valve.
If sealing of blind valve is damaged, gasket can be replaced at site easily.