TPT September 2012

Technology News

Effective support for longevity of pipes PROTECTIVE and resistant coatings applied during pipe manufacture, as well as manually on-site, are the tools of choice for reducing damage caused by corrosion. These thin shields against mechanical and chemical attacks need support by a careful and professional check for cracks, pores or other damage. A check of the protective coating by means of high voltage impulses can provide the certainty that unprotected spots, which are consequently targets for corrosion, are detected no matter how small. A reliable method needs to be able to find material defects such as pores and cracks; other mechanical damage; and the results of handling errors in applying the coating material. The testing of coverings and coatings with NDT devices that make use of pulse-type high voltage technology has been introduced worldwide due to its many advantages. Isotest ® equipment based on this technology supplies the required safety margin, and can maintain the chosen testing voltage even when facing rough conditions and growing pipe diameters. Two major components are important in this context: the built-in sphere gap, which stabilises high voltage permanently; and powerful and automatic regulation of the test voltage, which guarantees that even under demanding test conditions, such as moisture on the surface, the voltage is adjusted to the set value in a fraction of a second. If the pipe is still lying or hanging freely, a spiral electrode can perform an all-embracing job, and the test can be done in a single step, around the complete circumference of the pipe. This is also the easiest and quickest way to test longer sections of pipe. If the pipe has already been laid in the trench, a half-round brush is a suitable alternative. This is the easiest and quickest method when there is a longer section ahead. In addition to electrodes for the testing of the outer circumference, which generally involves the more robust type of coating, there are various types for thin or delicate coatings. In these cases the metal brush set is replaced by a special type of conductive rubber. A further alternative may be an electrode for the testing of the inside of the pipes, combining stainless steel and nylon bristles. The use of a grounding sleeve has proved its worth in cases where a conductive connection to the test object cannot be reached. It is also recommended to use a grounding sleeve on poorly conductive or extremely dry ground. The grounding sleeve consists of a special type of conductive rubber and represents a form of capacitive grounding that can only be achieved by using pulse-type testing technology.

True Profiles

TubeProfiler TM Mill Gauge

• Real time profile measurement • Diameter, ovality, straightness , length • Full cross section shape with no blind spots • Faster mill set up • Applications: Hot or cold Tube & Pipes, round, square, rectangular

C O N T R O L B Y M E A S U R E M E N T

www.limab.com

Elmed Dr Ing Mense GmbH – Germany Fax: +49 2056 93 2933 Email: info@isotest.de Website: www.isotest.de

Laser and inspection systems for true dimensional measurement

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S eptember 2012