Storage tank vapor systems today are designed to be closed systems (non venting). This means that flash from liquids being stored are routed to a lower pressure source (flare or VRU) to prevent release of tank vapors to the atmosphere these tank systems are considered positive pressure systems. In the event that the vapor space of the tank battery need to be vented the entire contents of emissions and flash are vented to atmosphere. The 8”thief hatch is the #1 means of venting tanks. The reasons why are LDAR, hatch maintenance, daily gauging or periodic gauging.

To design storage tank batteries with the ability to isolate any port or at least any port that may need to be accessed for any reason while liquid hydrocarbons are being stored. The ability to isolate allows for no venting, immediate repair and testing of components.

Until now, the Effect inc. patent pending “Hatch Valve” is the long-awaited lock open block valve for a Thief Hatch. This valve will do for the Industry today what the block valve has been accomplishing for high pressure reliefs for 20 years. Thief Hatch repairs and testing can now be performed safely and without venting (emissions).