Seamless tubing

For the most comprehensive inspection of seamless tubing, a rotating system is used in conjunction with an encircling coil. The rotating system is extremely sensitive to longitudinal, homogenous cracks and fissures while the encircling coil is ideal for finding short transverse defects.


  • Inspection: Encircling coil for full-body inspection. For a more thorough inspection, a rotating system is used simultaneously for identifying longitudinal grooves.

  • Production types: Continuous drawing lines and level winders, hot rolling lines

  • Materials tested: Ferrous, austenitic, nonferrous aluminum, copper, brass, titanium, german silver, etc.


Seamless tubing

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Encircling coil 


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Eddy current testing

Eddy current testing is a fully automatic, easy-to-install nondestructive testing method that provides reliable test results to verify product excellence. It uses electromagnetic induction to detect flaws in all metal materials.

Eddy current testing works in multiple environments

One of the most important testing methods used by industry today, eddy current testing provides immediate feedback on product integrity, allowing correction of process changes before scrap develops and delivers reliable test results.

Eddy current testing methods

Full-body inspection / Leakage testing

Full-body inspection using 4 segment coils.
  • Internationally recognized test standards: Leakage testing according to SEP, DIN, ASTM, API, BS, JIS, ETTC, ENEL and others
  • Inspection: Full-body inspection using encircling coils or multiple segment coils. Often combined with weld seam testing
  • Materials tested: Any ferrous, nonferrous or austenitic materials
  • Tube size: Up to 12 in (30.5 cm)
  • Production speeds: 1–20m/min (3.3–656 fpm). Depends on production line and welding type
  • Magnetization: For ferrous tubes

Eddy current testing is an excellent means of ensuring that tubing is leak-proof. Tubes are tested by encircling coils or multiple segment coils that completely surround the tube body. The eddy current test equipment paint-marks critical defects and assigns each tube to a sort class according to its quality. Test results are fully documented for future verification of tube quality.

Rotational testing

Online testing of steel bar with rotating system RS35HS and EDDYCHEK 5
  • Products tested: All seamless products that are round or off-round
  • Production types: Straightening lines, continuous drawing lines, offline final inspection
  • Inspection: Integrated into production line or used in final offline inspection
  • Materials tested: Ferrous, austenitic, nonferrous metals
  • Test piece diameter: 1,9 –140 mm (0.075–5.512 in)


PRÜFTECHNIK's rotating systems are designed specifically to identify longitudinal, homogenous cracks and fissures found at the surface of the test piece. They are used for products that have a tendency to show longitudinal defects but do not have seam welds. Because the encircling coil is ideal for finding short transverse defects, it is often used in conjunction with the rotating system for a comprehensive testing strategy. 

PRÜFTECHNIK offers a series of rotating systems (RS20, RS35HS, RS65, RS140) to cover a wide range of tube diameters. They are particularly easy to operate and maintain and are extremely robust to withstand the industrial environment. Precise test piece guidance and a lift-off compensation system ensure accurate test results.

Eddy current inspection equipment suited for use with the rotating system includes the EDDYCHEK S, EDDYCHEK 5 advanced ROT and the EDDYCHEK 610, depending on the testing capabilities required.

Inline testing

Inline testing
    • Input control: Identification of bad quality material, e.g. rolled wire (drawing lines for thick wire), bar, tube or pipe
    • Quality control: Detection of defective areas in test material and assignment of test piece to a quality category
    • Process control: Monitoring of production lines to avoid scrap, e.g. through transport mechanisms causing periodic defects
    • Final inspection: Assurance of crack-free material
    • Typical defects: Laps, holes, longitudinal cracks, tension cracks from annealing (wire), damage from transport devices (tube, bar, wire), damage through defective drawing lines (wire) or rollers (hot rod)

    Inline testing of tube, bar, and wire takes place in the production line at the time the material is produced. It assures that the material is free of cracks, holes and other material defects or periodic defects as even small surface defects can lead to defective end products, critical in items such as surgical instruments. Eddy current testing is extremely successful in detecting surface defects at various stages during the production process. For the best test results, encircling testing is used together with rotational testing. This testing method is also highly recommendable for hot environments such as hot rolled bar or hot rolled ferrous rod production.

    Offline testing

    Final quality check with encircling coil and magnetizing unit.
    • Offline inspection: Final inspection of cut-to-length tubes, e.g. after drawing to precise diameter (precision tubes)
    • Conveyors: PRÜFTECHNIK also provides conveyor systems for transporting tubes
    • Materials tested: Any ferrous, nonferrous or austenitic materials
    • Magnetization: Required for ferrous metals
    • End-to-end testing: Eddy current sensors are used for distinguishing individual pieces in end-to-end testing

    Tubes are tested offline for a final quality check before delivery. Also, tubes that were sorted to scrap in the course of inline testing during production may be retested offline for more precise classification or for cutting out of defect-free sections. PRÜFTECHNIK supplies complete, customized conveyor systems and testing tables for offline inspection.

    PRÜFTECHNIK offers a wide variety of eddy current inspection equipment that ranges from the most basic testers to powerful inspection systems with wide-reaching capabilites for integration into central production control systems and 8-channel inspection using multiple coil systems.

    End-to-end testing
    The eddy current sensor EDDYSENSOR is used instead of a light barrier to distinguish between individual test pieces in end-to-end testing.

    Butt weld / Seam weld detection

    EDDYSENSOR detects butt welds along steel wire.
    EDDYSENSOR detects weld seams along steel pipes

    Butt weld
    Butt welds cannot be identified by simple detectors such as the light barrier or proximity switch. The EDDYSENSOR locates the butt weld using eddy current testing methods and transmits a signal to the control unit.


    Weld seam
    The EDDYSENSOR eddy current equipment is ideal for detecting a weld seam so that the seam can be positioned where needed for tube-forming processes such as bending.

    Weld seam testing

    Weld seam testing with 2 segment coils.
    • International test standards: Weld seam testing according to SEP, DIN, STM, PI, BS, JIS, ETTC, ENEL, etc.
    • Welding lines: All welding methods such as TIG, laser, HF and ERW welding
    • Materials tested: Ferrous, austenitic, duplex grades, nonferrous aluminum, copper, brass, titanium and german silver
    • Combination inspection: Simultaneous weld seam testing and full-body inspection
    • Line speeds: 0.1–200 m/min (0.3–660 fpm)
    • Tube sizes: 0.5–600 mm (0.2–23½ in)

    Eddy current testing readily identifies flaws in the weld seam regardless of what welding procedure is used. The defects are color-marked and the tube is assigned a sort class according to its quality. Test results are fully documented for future reference.