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Jet Deflection Flow Detectors
Published in Béla G. Lipták, Flow Measurement, 2020
The hot-tapping procedure is shown step-by-step in Figure 7c. First a weld neck flange is welded to the pipe that is to be tapped. Next a flanged gate valve is made up to the flange. The third step is to bolt a hot-tap machine to the downstream side of the gate valve and open the valve. The hot-tap machine is used to drill the opening into the process pipe. The pressure seal on a hot-tap machine is similar to that of a control valve packing box, allowing taps to be made in pipes that contain relatively high pressures. The drilling assembly shown in the figure is hand-operated, but units are also available with pneumatic or electric drives. A scale on the machine enables the operator to know how far he has drilled into the pipe. After the hole is made, the bit is retracted, the valve is closed, and the hot tap machine is removed. The tap is now ready for the installation of the flow element, gland nut, and chamber, as shown in Figure 7b. Rigid safety procedures must be enforced during hot-tapping operations, particularly if the process is flammable or hazardous. Hot-tapping can only be performed if the piping specification does not require that welds be stress-relieved, and if there is flow in the pipe, so that the heat of welding and drilling is removed.
Methodology for ranking internal corrosion-induced leakage susceptibility in oilfield pipelines
Published in Corrosion Engineering, Science and Technology, 2023
OCM devices are equipped [6] with access fittings (AFs), which enable on-stream corrosion assessment of fluids under high production pressure in oil and gas operation. AFs are precision fabricated components, usually made of bare carbon steel, that are attached to pipelines and process vessels by welding. Following weld integrity checks, appropriate hole is ‘hot- tapped’ into the fluids, on-stream, while under pressure. Hot-tapping, also called pressure-tapping, is a technique of connecting any device to an existing oilfield pipeline without interrupting the fluid flow under pressure.