TPT-January-2015

Technology News

Producing and testing stainless steel tube to meet rising demands MAGNETIC Analysis Corp (MAC) Echomac ® ultrasonic inspection India, is testing welded stainless steel heat exchanger tube to meet industry standards.

transverse, three for wall thickness and OD/ID measurement, and one for water temperature compensation to enable dimensional measurement. This is the second system of this type that MAC has supplied to the company. Both are operating very satisfactorily, according to the company. MAC has also supplied several ultrasonic test systems to Schoeller Werk in Germany, to inspect heat exchanger tubing made of stainless steel and titanium alloys. In addition to detecting defects, the company uses these test systems to provide quick feedback to the operators on any changes taking place in the welding process. One system incorporates seven ultrasonic channels, while the other includes 14 channels. MAC also supplied a complete inlet table and outlet conveyor. Eddy current test systems are also generally required to inspect any tubing that is to be used for fluid transmission. When using eddy current technology, care must be taken when testing 300 series welded tube. Generally, the 300 series is close to being non-magnetic, while the 400 series is much closer to being magnetic. However, where 300 series tube is being welded, the weld can become ‘delta ferritic’, which creates permeability noise that will interfere with an eddy current test. This problem can be solved by ‘saturating’ the tube by means of a direct current coil, which MAC can supply. When this is done, the permeability becomes relatively uniform and the noise is minimised. It is also possible to avoid the permeability noise by testing the product after it has been annealed.

systems are being used by a number of tube manufacturers who supply steel tube for heat exchanger applications. A recent installation at Ratnamani Metals & Tubes Ltd, a steel tube producer in

The system incorporates an Echomac ultrasonic instrument with an ultrasonic rotary containing eight transducers – two for detecting longitudinal defects, two for

Magnetic Analysis Corp – USA Email: info@mac-ndt.com Website: www.mac-ndt.com

Echomac ultrasonic inspection system

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J anuary 2015