Total equipment isolation valves cannot gaurantee 100% leakage free.

Leakage trouble may cause big loses of industrial equipment such as contamination of fluid mixing, personal accident by inhalation of toxic gases or unexpected explotion that leads to occasionally huge disatser.

Typical blank work have been had actual problems at site as follows:

* Environment pollution during blinding work
* Exposure to hazard of toxic fluid to worker
* Potential hazard of sparking
* Need tools, gasket, cranes etc
* In need of Specialist or trained worker
* High labor cost
* Long total shutoff time

* Zoekterm: scheepvaart, marine, line blind, BOXY