Abstract: Methods and apparatus for a bi-directional dual chamber orifice fitting comprising a body with a chamber in fluid communication with a flow bore. The fitting also comprises an orifice supported by an orifice plate carrier that is selectably disposable in the bore. In the preferred embodiment, the lower chamber includes two passageways connecting the chamber to the flow bore. One passageway is located on either side of the orifice plate. Each passageway may also be equipped with a check valve to permit flow in only one direction through the passageway. In operation, the passageway on the upstream side of the orifice would allow fluid to flow into the lower chamber while the passageway on the downstream side would prevent flow back into the flow bore.