Eddy Current, Ultrasonic or Flux Leakage techniques can be used to inspect welded, extruded, and seamless tubing. The choice depends on the nonconforming conditions you wish to detect and the size, including wall thickness, and characteristics of the material. MAC instruments can handle a range of metal materials with a uniform cross section, including squares, rectangles, hex and round in cut lengths or continuous production. Carbon steels, stainless alloys, copper, aluminum, titanium and all other non ferrous metals can be inspected. Additional items such as markers, controls, demagnetizers, and components for mounting the encircling or segment test coils, saturation coils, rotaries, and for positioning and driving the material through the test, are combined with the instrumentation to make up a complete test system.

Short Surface & Subsurface OD Cracks and Weldline Defects
For detecting typical defects such as small, short incomplete welds, inclusions, voids or cavities and some subsurface cracks in carbon steel or non ferrous tube, a standard eddy current instrument such as the MAC 400 or MultiMac® is often selected, with segment or encircling test coils. The choice between segment or encircling coils is usually determined by the wall thickness. The MAC 400 can be supplied with up to four test channels and the MultiMac has up to eight test channels for applications that require greater capability.

ID Defects in Thin Wall Tube
While an ultrasonic test, such as with the Echomac FD-4 is generally the first choice for ID defects, some applications, particularly thin wall tubing, can be very successfully handled using eddy current instruments such as the MultiMac® or High Frequency Model ERIC VI. In these cases, careful setup using phase and amplitude thresholds, and other selective circuits can give accurate separation between signals for ID and signals for OD surface defects. The ERIC VI High Frequency Model, used with special design test coils, is particularly effective in testing thin wall tubing for medical and other high performance applications.

Long Continuous Surface Defects
For detecting long, continuous surface defects such as seams and laps in tube, the MultiMac® ,used with rotary test probes, is the most appropriate. By rotating multiple test probes at speeds up to 6000 RPM around the tubing, even relatively short flaws can be reliably detected in many applications, without sacrificing throughput speed.

Both Short and Long Continuous Surface & Subsurface Defects
For applications where both short and long surface and subsurface defects need to be detected simultaneously, the new MultiMac multi mode eddy current tester would be an excellent choice. With up to 8 channels, each of which can be individually configured for encircling test coils, sector/tangent test coils, or rotating test probes, a comprehensive test is possible. The MultiMac may also, in some instances, be appropriate for detecting ID defects in thin wall tube.

Internal, ID and OD Defects in Heavy Wall Oil Country Goods
Inspecting for defects in heavy wall pipe and tube is best done using flux leakage or ultrasonic techniques. The Rotoflux® tester handles up to 16" diameter ferrous tube and the Echomac FD-4 FD-4 instrumentation is suitable for ferrous and nonferrous tube up to 6" diameter. Special handling components are available for difficult conditions such as upset ends.

Internal Longitudinal and Transverse Flaws
For internal longitudinal and transverse, including oblique orientation flaws, and ID defects, ultrasonic inspection techniques are often the best choice. MAC's multi channel Echomac FD-4 instrumentation and the Echomac rotary transducer assembly, with its unique rotating seal-less water coupling system permits ultrasonic inspection at high throughput speeds. The FD-4 can also be utilized with squirter couplants and existing water immersion systems.

Wall Thickness & ID/OD Measurement
An ultrasonic instrument, such as the Echomac FD-4 provides a separate wall thickness circuit for accurate measurement of tube wall. The FD-4, with its OD measurement capability, can report OD and ID dimensions and ovality, in addition to wall thickness, eccentricity, and wall variation.

Both Short and Long Continuous Defects
For those applications that require the detection of both short and long continuous surface defects, the new MultiMac® tester would be the right choice. The MultiMac with up to 8 test channels, allows simultaneous detection of both types of defects in magnetic or nonmagnetic material.

Alloy and Hardness Detection
Variations in alloy, heat treatment, case depth and hardness can be successfully detected by MAC's comparators. The Varimac® eddy current comparator can be used on a range of product types including non magnetic stainless. Variations in carbon steel and special alloy bar can also be detected with the Production Comparator low frequency electromagnetic comparator.

In Situ Defect Detection in Heat Exchanger Tube
To detect defects such as corrosive pitting, holes, erosion, fatigue cracks, and OD wear at the tube supports in non magnetic heat exchanger tubing, an eddy current tester such as the Promac Mac 140 tester is appropriate. With optional tube mapping software, immediate tube maps can be printed to show test results. MAC also has test equipment which is suitable, with magnet test probes, for in situ detection in certain thin wall, small diameter magnetic alloys.

Combined Systems
For applications where more than one of the conditions described above must be met, Multiple Test Systems using several testers or technologies can be assembled. In these cases, each tester or technology is used to find the types of defects or conditions that it is best suited to detect. The result is often a more accurate test and fewer rejects to allow more of your product to be shipped to your customer.