Importance

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Abstract

A test apparatus 10 for testing the diameter of oilfield tubulars having various nominal diameters includes a machine frame 12 for successively receiving the axially movable tubulars, and upper and lower radially opposing carriages 16 and 18 each movable relative to the machine frame. First and second light generating sources 24 and 26 are each mounted on a respective carriage and transmit a wide light beam directed to intersect radially opposing sides in the oilfield tubular, such that the width of each light beams is reduced by engagement with the tubular. First and second light detectors 28 and 30 are each mounted on the carriages and are positioned for detecting the position of the reduced width light beams relative to the carriages and generating test signals in response thereto. Computer 32 is provided for receiving test signals from the sensors and generating a tubular diameter test measurement in response thereto. The test apparatus includes upper and lower optical shutters 52 and 54 each mounted on the carriages and movable from an active standardization check position to an inactive position. Each shutter has an opening therein for transmitting a preselected reduced width light beam past the shutter. Micrometer 56 is provided for measuring a radial spacing between the first and second carriages and generating a carriage spacing signal in response thereto. According to the method of the invention, a specific test specimen 42, 44 is positioned for calibrating the spacing between the carriages. The carriages are then moved to a standardization position and shutters are used to perform a standardization check on the equipment. Assuming this standardization check is passed, the shutters are moved to an inactive position and tubulars then tested for diameter and ovality. Significant savings are realized by not having to recalibrate the test apparatus for each size nominal diameter tubular being tested, and by not requiring a test standard for each size tubular capable of being tested.

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First Claim