In-line Inspections

In-line inspection (ILI) tools, also commonly called smart or intelligent pigs, are cylinder-shaped electronic devices used by the pipeline industry to detect loss of metal and in some cases deformations 

Metal loss tools are used to detect defects that have resulted in wall thinning in a pipeline. They can discriminate to some extent between manufacturing defects, corrosion defects and mechanical damage. There are two main typ es of tools  

Ultrasonic (UT) wall measurement tools use the ultrasound echo time technique for measuring the remaining wall thickness. The UT tool transmits an ultrasonic pulse into the pipe 

Crack detection tools are typically designed for longitudinal crack detection, but they can also be adapted to circumferential crack detection. 

UT crack detection tool generates an ultrasonic signal into the pipe wall that is reflected off the internal and outer surfaces of the pipe. If a crack is detected, the signal reflects back along the same path of the tool. Since a liquid couplant is required between the sensors and the pipe wall, this tool works only with liquid pipelines. 

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Strain in dents may be estimated using data from deformation in-line inspection (ILI) tools or from direct measurement of the deformation contour. Direct measurement techniques may consist of any method capable of describing the depth and shape terms needed to estimate strain. The strain estimating techniques may differ depending on the type of data available. Interpolation or other mathematical techniques may be used to develop surface contour information from ILI or direct measurement data. Although a method for estimating strain is described herein, it is not intended to preclude the use of other strain estimating techniques. See also Fig. D-l. 

Shindo, W, Wang, E. H., Akella, R., Strojwas, A. J., Tomlinson, W, and Bartholomew, R. (1999), Effective Excursion Detection by Defect Type Grouping in In-line Inspection and Classification, IEEE Transactions on Semiconductor Manufacturing, Vol. 12, No. 1, pp. 3-10. 

In-line inspections (ILI) are useful in obtaining a profile of defects in a pipeline. High-resolution UT and MFL ILI tools can be used to determine the geometry and orientation of corrosion defects. 

For gas distribution piping, corrosion mitigation is primarily sacrificial CP. Techniques such as in-line inspection are typically not an option for the relatively complex network of distribution mains and services, which makes integrity assessment of the piping difficult if not impossible. 

Inspection pigs (also referred to as in-line inspection pigs, smart pigs, and intelligent pigs ) are used to collect data (including, but not limited to, corrosion) from within the pipe using two methods ... 

FIGURE 4.41 Zones of effectiveness of circumferential and axial MFL. (From Bubenik T., Magnetic flux leakage. In the Proceedings of the In-line Inspection Symposium, California Public Utilities Commission, June 24, 2011. With permission.)... 

An in-line inspection system is an integral part of the manufacturing system and therefore has to be included in the global cost and benefit analysis when evaluating the overall investment of the production faciUty. Besides the overall cost of the production equipment, the following economic factors specifically related to the metrology system should be included in the economic analysis (Kunzmann et al. 2005) ... 

Mechanical. Manholes, isolation facilities, vents, drains, cleanout/ steamout facilities, and access all acceptable for entry and maintenance correct interface for agitators, etc. correct shape and finish for internal lining system (if any) correct configuration and types of clip for refractory and insulation (for all vessels requiring them, but especially for heat-treated vessels) provision for in-line inspection (tell-tales, underfloor drainage) when needed transport... 

Waker, S., Rosea, G, and Hylton, M. In-line inspection tool selection. CORROSION 2004, Paper 168. Houston, Tex. NACE International, 2004. 

Schmidt R (2004) Unpiggable pipelines - What a challenge for in-line inspection. Pigging Products and Services Association (PPSA) www.ppsa-online.com/papers.plp Verleun T (2004) Cleaning of oil gas pipelines. Pigging Products and Services Association (PPSA) www.ppsa-otdine.com/papers.php Jack TR (2002) Biological corrosion failures. ASM International... 

In Figure 19.8, the transmittance spectra of six pharmaceuticals in two groups, each of which has three pharmaceuticals, in the region of 0-100 cm are shown. These spectra were measured from the tablets of these pharmaceuticals. A useful characteristic of THz-TDS is that such measurements can be made directly, so that it is hopeful that THz-TDS will be used in the future as an in-line inspection tool at the site of manufacturing pharmaceutical tablets. 

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