Inspection of Large Tubes Using Sensor Arrays

The eddy current inspection system was designed for detecting surface defects (e.g. cracks, pores) on hot-rolled tubes. The diameter range spans from 50 mm (2") up to 300 mm (12"), the tube length might vary between 3 m ( ~10 ft) and 15 m (~50 ft). During the inspection the tube is rotated by means of rotating rollers, while the trolley moves the 48-coil sensor array along the tube's axis. The external multiplexer switches with a rate of 32 kHz, so a maximum scan speed of 1.5 m/s can be achieved. A special analysis software provides not alone the GOOD/BAD classification, also the actual defect length is displayed on the operator panel. Using a colour marking device the actual defect position is labeled.

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  • V-shaped rollers used for tube transport
  • cylindrical twin rollers used to rotate the tube (adjustable rotational speed: 0.5 … 1.3 m/s)
  • trolley driven along the tube’s axis by a DC-motor (adjustable axial speed: 0.5 … 1.3 m/s)
  • adjustable vertical position of probe holder (depending on tube diameter)
  • pneumatic lowering/lifting of the probe holder
  • gapless scan of tube’s outer surface due to overlapping probe arrangement
  • 48-coil array (24 dual probes)
  • external multiplexer (32 kHz multiplex rate)
  • reference notches used for calibration: hole 1.8 mm (60 mm tube diameter) / hole 3. 2 mm (180 mm tube diameter) / hole 3.7 mm (272 mm tube diameter) / axial flaws from 5 % of wall thickness on (depth 0.3 mm … 1.3 mm, length 50 mm)
  • input of tube dimensions (diameter, length)
  • input of test speed (helical scan)
  • automatic calculation of rotational speed (tube) and axial speed (trolley) depending on tube dimensions
  • operating mode control (automatic, transport, manual) as well as manual probe lowering/lifting
  • menu navigation via graphic user interface incl. graphic output of test results and status information

System Data

  • inspection mechanics (frame with main beam, trolley with probe holder, roller conveyor)
  • 6-channel eddy current instrument PL500 with ProFiBus I/O module
  • external multiplexer
  • 24 dual probes (48-coil-array)
  • control cabinet
  • operator panel incl. display
  • colour marking device
  • light barrier (surveillance of danger zone)

Products in use

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Dillinger manufactures technologically outstanding and versatile heavy plates at the traditional Saar location. References in a wide variety of application areas are available worldwide. Especially for pipeline applications, the HST test procedure developed by ROHMANN supports the precision and consistently high quality of Dillinger products. Dillinger Hütte

Eisenwerk Brühl GmbH specializes in the development and mass production of cast iron engine blocks for the automotive industry. The company is one of the most important suppliers of cast iron ZKG for the passenger car sector. To secure the production process, i.e. for the detection of material defects, hand and line testing devices from ROHMANN are used. Eisenwerk Brühl GmbH

As a subsidiary of the Etihad Aviation Group, the company offers services in the areas of line, light and heavy maintenance. The largest service provider for commercial aircraft in the field of maintenance, repair and operation in the Middle East, uses both the ELOTEST M2 handheld tester and the ELOWHEEL 1000 rim tester (RPT16) for inspecting their aircrafts. Etihad Airways Engineering

Stüken is the world market leader for deep-drawn components, punch and deflection parts of maximum precision and reliably high quality. For automated quality assurance, i.e. for the detection of material and structure defects, Stüken uses line testing equipment, e.g. the ELOTEST PL600 from ROHMANN. Hubert Stüken GmbH & Co. KG

Lufthansa Technik offers a complete service for aircraft technical services, such as maintenance, overhaul and testing of engines and chassis. In addition to the robot-based ELOSCAN test systems, Lufthansa Technik AG also uses sensors and portable test equipment from ROHMANN at several locations in Germany. Lufthansa Technik AG

NKT is a well-established and global supplier of turnkey DC and AC cable systems, providing world-class energy transport with innovative cable solutions. To ensure the quality of its own products, NKT uses the line tester ELOTEST IS500 from ROHMANN. NKT Group GmbH

Siemens Power Generation Services provides worldwide service solutions for gas or steam turbines, generators or wind turbines to increase the efficiency, reliability and operational flexibility of plants. In its global maintenance services, the company uses a.o. the ROHMANN handheld tester ELOTEST M3. Siemens

As a traditional aviation manufacturing and maintenance company, Zeppelin offers professional QM services to the global aviation industry, the automotive industry and mechanical and plant engineering. For the aerospace sector, Zeppelin carries out ZFP training courses using ROHMANN handheld testers Elotest M3, test probes and calibration standards. Zeppelin Systems GmbH

ZF is a leading global technology group in driveline and chassis technology as well as active and passive safety technology. ZF uses a wide range of innovative solutions from ROHMANN for various testing tasks in the field of crack and structural testing. ZF Friedrichshafen AG