Source google image: http://www.cw-estgroup.com/App_Themes/CWEST/Videos/10-Double-Block-and-Bleed-Test-Isolation-Plugs/Double-Block-and-Bleed-Test-Isolation-Plugs.jpg
Double isolation
Source google image: http://www.cw-estgroup.com/App_Themes/CWEST/Videos/10-Double-Block-and-Bleed-Test-Isolation-Plugs/Double-Block-and-Bleed-Test-Isolation-Plugs.jpg