Importance

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Abstract

An orifice fitting for measuring the flow of gas through a pipeline in which the orifice fitting has a body including a pair of opposing body plates that define a body chamber. Passing through both body plates is an aligned flow passage for attachment to a gas pipeline. One of the body plates includes an access opening that is selectively covered and sealed by a hatch. A carrier having a carrier chamber is movably positioned within the body chamber so that the carrier chamber can be selectively aligned with the flow passage or the access opening. Removably positioned within the carrier chamber is an orifice disk having an orifice of a predetermined size through which gas can flow when the carrier chamber is aligned with the flow passage. The carrier chamber is sealed from the body chamber by seal rings positioned on opposing sides of the carrier and biased against the body plates. When the carrier chamber is aligned with the access opening, an annular injection groove positioned on each sealing ring communicates with respective injection passages extending through the body plates, thereby permitting a sealant to be injected into the injection groove for emergency sealing of the carrier chamber. The orifice fitting further includes a valve assembly extending through one of body plates and communicating with the carrier chamber. Extending from the valve assembly is a venting passage that permits the gas from the carrier chamber to be vented to the atmosphere at a distance from the valve assembly.

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First Claim