Multi-Double Block and Bleed System for an Orifice Fitting

摘要

A system and method for providing a multi-double block and bleed configuration in an orifice fitting to provide an additional barrier of protection between the pressurized flow stream and the environment outside the flowmeter. The multi-double block and bleed system includes a first pair of blocking valves located below a second pair of blocking valves. The multi-double block and bleed system further includes a first vent valve positioned between blocking valves of the first pair blocking valves, a second vent valve positioned between blocking valves of the second pair of blocking valves, and a third vent valve positioned between the first and second pairs of blocking valves. The pairs of blocking valves and the vent valves are arranged to provide double block and bleed during all phases of orifice plate installation and removal.

主权项

1. A multi-double block and bleed system for use with an orifice fitting, the multi-double block and bleed system comprising:
an orifice plate transfer passage through which an orifice plate is moved in the flowmeter; four blocking valves disposed in series in the orifice plate transfer passage, each of the blocking valves configured to block escape of fluid from the flowmeter through the orifice plate transfer passage; and three vent valves, each of the vent valves disposed between two adjacent ones of the blocking valves, and configured to provide an outlet for fluid in the orifice plate transfer passage; wherein the four blocking valves comprise:
a bottom valve that is adjacent to a lower chamber of the flowmeter;a lower valve that is adjacent to the bottom valve;a top valve that is farthest of the blocking valves from the lower chamber; andan upper valve that is disposed between the lower valve and the top valve.