Non Destructive Testing and Inspection

Visual
Visual Examination is generally used to determine such things as the surface condition of the part, reinforcement and undercutting of welds, alignment of mating surfaces, shape or evidence of leaking. Methods employed may be either:

(a) direct visual examination,
(b) remote visual examination, or
(c) translucent visual examination using artificial directional lighting.

Applus RTD provides certified visual inspectors to various codes, such as: AWS, API, ANSI, ASME, and ASNT.

Radiography
A method commonly used to examine surface and subsurface discontinuities, radiographic testing can detect voids, porosity, inclusions and cracks in castings and weldments in a wide range of materials, sizes, and shapes. The interpretation of radiographic film of welds requires knowledge of not only welding and welding discontinuities, but also the exercise of good judgment as to whether the discontinuities are actually defects. Applus RTD radiography technicians have extensive experience in film interpretation at both Level II and Level III status.

Digital Radiography
Digital Radiography combines conventional radiography with digitized computer imaging. The radiographic technique remains the same without the headaches. The advantages of digital radiography are overwhelming. The era of evacuating whole structures, floors, and entire operating areas of personnel in order to perform radiography has all but been eliminated.

Phosphor imaging plates are used in place of traditional x-ray emulsion film which allows images to be captured more readily with the use of weaker sources. Decreased radioactive source strength allows for smaller barriers, virtually eliminating the need to evacuate areas. Exposure times are decreased by 75%, which in turn has increased productivity, yielding higher results. Exposures can be taken within 10’ – 15’ of personnel, safely without interruption. The phosphor imaging plates can be re-used thousands of times, eliminating film costs. Since chemicals are no longer required to develop the images, there is no time lost in developing and drying while generating no hazardous waste.

The imaging plates are sent through an electronic scanner and in less than 90 seconds is on your computer screen. The image can then be reduced, magnified, rotated, inverted or switched between a positive and negative image for better viewing. The unique software package has the ability to adjust the contrast and density thresholds making it possible to evaluate a multitude of thicknesses from one exposure. This feature in its self has virtually eliminated the need for re-shoots and use of multiple film speeds. Densities of each area of concern can be controlled for the best possible viewing, enhancing definition and contrast to interpret any and all discontinuities with precision and accuracy. A built-in feature allows for taking measurements, evaluating wall thicknesses, insertion of annotations and digital picture for better overall documentation.

Results can be printed, e-mailed or inserted into word documents for others to examine. X-rays are typically viewed through an intense light source and is difficult to replicate. Digital radiography has rendered film storage obsolete. Images are archived on CD or hard drive, retrievable, and able to transmit effortlessly to others around the world. This process allows multiple inspectors/engineers the efficiency of real-time evaluation of the same radiographic image no matter where they are.

Inspections that were once impractical or unachievable, can now be successfully completed with the use of digital radiography. In process piping under insulation in close proximity with personnel, large bore piping, valves, and castings can now be inspected safely and in a way that is cost-effective. The detection of corrosion under insulation, (CUI), flow-accelerated corrosion (FAC), and under-deposit corrosion of smaller pressure vessels using digital radiography has been a proven significant cost savings.

Advantages of Digital Radiography

• Decrease Source Strength
• Decrease Barrier Distance
• Increased Accuracy
• Advanced Communications
• Image Analysis
• Image Enhancement
• Increased Productivity
• No Chemicals, No Hazardous Waste
• No Film or Processors

Magnetic Particle
The magnetic particle method can be used on ferromagnetic materials to reveal surface discontinuities and, to a limited degree, those located below the surface. Because the sensitivity of this method decreases rapidly with depths below the surface being examined, it used primarily to examine for surface discontinuities. Applus RTD offers large, stationary in-house test units for high volume inspection and a full range of portable units designed for reliable, efficient testing in the field.

Penetrant Testing
The liquid penetrant method is used to detect discontinuities which are open to the surface of the material being examined. This method may be used on both ferrous and nonferrous materials. Liquid penetrant examination may be used for the detection of surface discontinuities such as cracks, seams, laps, cold shuts, laminations and porosity, Applus RTD provides both visible and fluorescent liquid penetrant examination services.

Leak Testing
Leak testing is performed using gas and bubble formation testing, vacuum testing, the halogen diode detector, the helium mass spectrometer reverse probe ("sniffer"), the helium mass spectrometer hood methods and the pressure change test.

Coatings & Linings
Applus RTD has experienced materials engineers that can make recommendations and develop specifications for the correct selection of exterior coatings and interior linings for your equipment. With expertise on systems, such as epoxies, phenolics, vinyl esters, urethanes, glass, rubber and fluoropolymers, Applus RTD engineers have the experience and expertise to conduct audits and recommendations on qualified vendors.

Coatings & Linings Inspections

• Reactors
• Heat Exchangers
• Storage Tanks
• Railcars
• Tank Trailers

Ultrasonic Testing
The ultrasonic method provides indications of surface and subsurface discontinuities, with the potential to determine the depth and exact size by the use of the proper technique. Ultrasonic pulses are directed into the test object which produces echoes and reflections which then indicate the presence, absence, and location of flaws, interface and/or discontinuities.

Ultrasonic examination for thickness determination may be made using either the resonance or pulse-echo technique. This technique determines thickness or reveals corrosion discontinuities near the surface or deep within components or structures. It offers the advantage of examining components without removal or disassembly.

Positive Material Identification
Positive Material Identification (PMI) is a process used to determine the elemental composition of materials. The test identifies the alloys that make up a particular material.  The purpose of alloy verification is to ensure that only materials that are specified as part of the design requirements are supplied and used.

Magnetic Flux Leakage
Applus RTD has found that Magnetic Flux Leakage (MFL) is the best suited technique for early detection of damage in the fin fan tubes. This method can detect corrosion at an early stage when the pit depth is only 20% of the tube wall, regardless of heavy deposits in the tubes. As for tube end grooving, even if it is located as close to a half-inch from the tube end, there is no better and faster technique. The aluminum fins don’t pose any problem as they are non-magnetic and don’t influence an MFL reading.

EMAT
The Electromagnetic Acoustic Transducer (EMAT) method allows thickness measurements of boiler tubes effectively ignoring layers of slag and corrosion on the tube surfaces without the use of couplant. This provides savings by eliminating sandblasting and cleaning services to the utilities.

The improvements since 1997 have provided increased power necessary to not only measure heavily scaled tubes but also chromized tubes. The technology has been successful at measuring tube wall thickness with an accuracy of +0.1mm through scale thickness as high as approximately ½ inch.

Applus RTD technicians are supplemented with AutoCAD technicians to collect, download and import the data into a visual representation of your boiler. The software compares acceptability criteria with field data and identifies erosion and corrosion issues on the fireside of the boiler. Engineers and managers can use this data to better understand and track areas susceptible to early failure.

The elimination of sandblasting allows a utility to minimize their outage schedule, reduce costs, and collect needed preventative and predictive maintenance data on the fireside surfaces without introducing silica to the fireside of the boiler.

Eddy Current
The Eddy Current method is used to detect discontinuities in pipe and tubing by subjecting the material to a strong external magnetic field. A test coil which includes eddy currents in the material is used for this purpose. If a discontinuity exists, there will be variations in the eddy currents produced and these will be indicated by a signal in the test apparatus.

Thermography
Thermography, or thermal imaging, is a type of infrared imaging. Thermographic cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 900–14,000 nanometers or 0.9–14 µm) and produce images of that radiation.

Non-contact thermometers have many uses. The most popular include:

• Predictive & Preventative Industrial Maintenance: check transformers, electrical panels, connectors, switchgear, rotating equipment and furnaces as examples
• Automotive: diagnose cylinder heads and heating/cooling systems.
• HVACR: monitor air stratification, supply/return registers and furnace performance.
• Food Service & Safety: scan holding, serving and storage temperatures.
• Process Control & Monitoring: check process temperature of steel, glass, plastics, cement, paper, food and beverage.

Internal Rotary Inspection System (I.R.I.S)
I.R.I.S. is the most accurate imaging method for heat exchanger tubing by acquiring the picture without pulling the tube. While other NDT techniques produce hard-to-interpret signals. I.R.I.S. provides the image of the tube wall while identifying corrosion, pitting and wall loss.

• For tubes from 0.5” to 3.5” diameter; any material: magnetic or non-magnetic.
• Easy to interpret with accurate wall loss measurement to the nearest 0.002”.
• Most economical, when combined with other test techniques. First, eddy current or magnetic flux leakage find defects and their location, then I.R.I.S. provides the accurate image of each defect.