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Coiled tubing 27 coiled tubing and line pipe are made

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Coiled Tubing 27 Coiled tubing and line pipe are made from electric welded carbon steel manufactured in various grades for use in oil and gas well servicing, coiled tubing drilling and installed well tubing. Tubing sizes are typically 25 mm (1 in.) to 89 mm 394 Electromagnetic Testing F IGURE 15. Scatter plot of magnetic flux leakage test signals for 73 mm (2.9 in.) outside diameter pipe. 0 10 20 30 40 50 60 70 80 90 Wall loss (percent) Signal amplitude (arbitrary unit) 30 20 10 0
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(3.5 in.) outside diameter with wall thicknesses varying from 2 mm (0.08 in.) to 6.3 mm (0.25 in.). Outside diameters of coiled line pipes range from 13 to 165 mm (0.5 in. to 6.5 in.). Strips are spooled onto drums. Strings are made by welding strips together, end to end, and then passing the strip through a high frequency induction electric resistance welding mill. The result is often a coiled string of length 6 to 10 km (4 to 6 mi). The testing of new coiled product is usually conducted according to American Petroleum Institute specifications. 16,28,29 Conventional nondestructive test methods are used: radiographic, ultrasonic and liquid penetrant testing, as well as electromagnetic techniques. The testing of used coiled tubing is different because the anticipated discontinuities differ from those for new product. However, the equipment for inservice testing follows from the desirability of noncontact testing of wall thickness, ovality, pitting, erosion and other damage. Five types of electromagnetic testing are important for the tubing body. 1. An electromagnetic sensing system for diameter measurement detects ballooning, necking and ovality. Standard eddy current standoff measurement sensors are mounted in a ring to detect changes in outside diameter (Fig. 16). Such ovality measurements are used in collapse pressure calculations. This measurement requires an unpitted outside surface or much compensation and averaging circuitry. 2. A magnetic reluctance wall thickness measurement system enables the thickness of the ambient wall (not localized pits) to be measured along the string, with thin areas caused by erosion, general corrosion and rubbing against the side of the well. These results can then be used for cross sectional area computations and maximum tensile forces for each section of a string. In this method, the field intensity measured with rings of hall effect sensors, placed next to the tube wall, is related to the wall thickness immediately below it as shown in Fig. 14. In principle, the number of poles at locations P 1 and P 2 affects the demagnetizing field H d , which in turn affects the tangential field in the sensor ring. 3. The same rings of sensors are also used for detection of pitting, gouges and transverse discontinuities by measuring their magnetic flux leakage. Signals from localized pitting can be electronically removed. Sensitivity to small surface imperfections depends on the liftoff from the tubing surface to the electromagnetic center of the sensor.
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  • Fall '19
  • Nondestructive testing, electromagnetic testing, Magnetic flux leakage

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