Advanced NDT

Time of Flight Diffraction (ToFD)

 

Time of Flight Diffraction (ToFD) is an advanced method of Ultrasonic inspection. It is a very sensitive and accurate method for non-destructive testing of discontinuities in welded joints.ToFD ultrasonic test method can perform crack sizing very precisely and allow the owner to run the equipments or plants until the critical crack depth and length  is not reached with  a minimal risk of failure. Conventional ultrasonic test method employs measuring of the amplitude of reflected signal which is relatively less reliable method of sizing defects because the amplitude strongly depends on the orientation of the crack. ToFD ultrasonic test method uses the time of flight of an ultrasonic pulse to determine the position of a discontinuity of interest. 

 

ToFD ultrasonic test system consists of a pair of probes placed on opposite sides of a weld. One of the probes emits an ultrasonic pulse that is collected by the probe on the other side. In undamaged pipe, the signals picked up by the receiver probe are from two waves, one that travels along the surface and one that reflects off the far wall. These ultrasonic waves are diffracted from the tip of the discontinuities, if present. The size of the discontinuity is calculated by measuring time of flight of the ultrasonic pulse. Compared to conventional ultrasonic testing, ToFD ultrasonic testing instruments and probes are complex and expensive and requires highly trained, skilled and experienced technicians.

Phased Array Ultrasonic Testing (PAUT)

 

Phased Array ultrasonic testing (PAUT) is an advanced method of ultrasonic testing. Phased array ultrasonic method can reveal  defects embedded in the material that cannot be easily resolved with conventional ultrasonic testing. 

 

Compared to conventional ultrasonic testing, Phased Array ultrasonic testing instruments and probes are complex and expensive and requires highly trained, skilled and experienced technicians. The Phased Array Ultrasonic Testing is highly recommended for critical discontinuities detection, sizing and monitoring in aerospace industry, power general industry, nuclear industry and petrochemical industry.

Eddy Current Testing

 

Multi-frequency eddy current systems refer to equipment that can drive inspection coils at more

 

than two frequencies. This type of instrumentation is used extensively for tubing inspection in Power Generation and the Oil and Gas industries. Major advantages of this inspection are the ability to increase inspection information collected from one probe pull, comparison of same discontinuity signal at different frequencies, mixing of frequencies that helps to reduce or eliminate sources of noise and improves detection, interpretation and sizing capabilities.

A critical component of any eddy current examination is the ability to calibrate the unit based on reference standards manufactured from the same or very similar material as the test specimen. In the case of tubing inspection an ASME tubing pit standard is required.

 

 

 

The advantages of Eddy Current inspection are: sensitive to small cracks and defects, detects surface and near surface defects, immediate results are available, equipment is portable, minimum part preparation is required, probes do not need to contact the part and the ability to inspection complex shapes and sizes of conductive materials. The limitations of Eddy Current include; only conductive materials can be inspected, skill and training required is more extensive than other techniques, surface finish and roughness may affect the test.

Videoscope Inspection Testing

 

Videoscopes Inspection offers the best image quality available in flexible scopes. The scopes are flexible so that they can be inserted into many applications, from gas turbines to process and high purity piping. They include distal tip articulation and interchangeable optical tip adapters to maximize image quality in the specifics of your application.

 

Available systems include :

  • High Resolution Display Camera

  • High Intensity Light Source

  • Camera Control Unit (CCU)

  • Digital Storage or Videotape

 

Videoscope applications:

 

  • Inspection/approval for pharmaceutical, chemical, food, power plant industries

  • Inspection/approval drinking water pipes and waste water technology

  • Inspection for heat exchangers

  • Examination of walls for deposits, erosion, corrosion, crack formations

  • Examination of electropolished piping, orbital weld seams, longitudinal weld seams

NDT by X-Ray Crawlers

 

The X-Ray Crawler is similar to conventional radiography however an x-ray source tube on a crawler device is run inside the pipe to each weld. The technique is quick and can inspect on average 150 welds per day. The biggest advantage of x-ray crawlers is their speed.

NDT by Scar Projector

 

A Portable gamma radiographic exposure device is specifically designed as a Small Controlled Area Radiography (SCAR) system. The SCAR projector is used primarily for the radiography of standard or difficult joint geometries without disruption and the need for large barrier areas. The SCAR system is comprised of a projector, a pneumatic control unit and a series of clamps to fit a variety of pipe sizes.

 

The system may be used with a maximum of 15 curies of Iridium-192 or 81 curies of Selenium-75. Lower activity sources with smaller focals are available. 

 

 Features:

  • Allows for 24 hours radiography

  • Highly directional beam

  • Reduces radiation dose

  • Sealed source does not leave the device during exposures

  • No flash dose during exposure or retraction of sealed source     

  • More production time for all trades

  • Locks to prevent unauthorized operation

  • Inspection through insulation for corrosion

Magnetic Flux Leakage (MFL)

 

The basic principle of this Non-Destructive Test is that a strong magnet induces a magnetic field in the material. At areas where there is corrosion or missing metal, a leakage field will arise. The output from the detector can be electronically digitalized for automated inspection systems. All indications is stored as well as their location. Bad areas or spots in plates can easily be identified and repaired. In the range 6 to 20 mm, all ferro-magnetic tank bottoms can be inspected, and (limited) coated surfaces also can be tested.

 

 

 

Magnetic Flux Leakage (MFL) is a method of Non-Destructive Testing, which is used to detect corrosion and pitting in steel structures, most commonly pipelines and storage tanks. MFL is a detection technique, which detects volumetrically changes. The disadvantage of Magnetic Flux Leakage is that no absolute values but relative volumetrically changes are reported. However it is a very suitable tool for detecting bad spots in the plates. After the fast MFL inspection is done, only the “suspicious” areas of the tank bottom surface will be quantified by the slow but more accurate Ultrasonic Testing.