Eddy Current Testing

(ECT)

Eddy current testing is a noncontact method used to inspect non-ferromagnetic tubing. This technique is suitable for detecting and sizing metal discontinuities such as corrosion, erosion, wear, pitting, baffle cuts, wall loss, and cracks in nonferrous materials. Two coils are excited with an electrical current, producing a magnetic field around them. The magnetic fields penetrate the tube material and generate opposing alternating currents in the material. These currents are called eddy currents. Any defects that change the eddy current flow also change the impedance of the coils in the probe. These changes in the impedance of the coils are measured and used to detect defects in the tube.

• Application: • Condensers • Feed water heaters • Coolers • Evaporators • Chillers

Remote Field Testing

(RFT)

Remote field testing (RFT) is being used to successfully inspect ferromagnetic tubing such as carbon steel or ferritic stainless steel. This technology offers good sensitivity when detecting and measuring volumetric defects resulting from erosion, corrosion, wear, and baffle cuts.

• Application: • Boiler Generating Bank tubes • Feed Water Heaters • Carbon Steel Heat Exchangers

Magnetic Flux Leakage

(MFL)

Magnetic flux leakage (MFL) is a fast inspection technique, suitable for measuring wall loss and detecting sharp defects such as pitting, grooving, and circumferential cracks. MFL is effective for aluminum-finned carbon steel tubes, because the magnetic field is almost completely unaffected by the presence of such fins.

• Application: • Air Coolers • Feed Water Heaters • Carbon Steel Heat Exchangers

Near Field Testing

(NFT)

Near field testing (NFT) technology is a rapid and inexpensive solution intended specifically for fin-fan carbon-steel tubing inspection. This new technology relies on a simple driver-pickup eddy current probe design providing very simple signal analysis. NFT is specifically suited to the detection of internal corrosion, erosion, or pitting on the inside of carbon steel tubing. The NFT probes measure lift-off or "fill factor," and convert it to amplitude-based signals (no phase analysis). Because the eddy current penetration is limited to the inner surface of the tube, NFT probes are not affected by the fin geometry on the outside of the tubes.

• Application: • Air Coolers • Carbon Steel Heat Exchangers

Internal Rotary Inspection System

(IRIS)

The ultrasonic IRIS option is used to inspect a wide range of materials, including ferrous, nonferrous, and nonmetallic tubing. This technique detects and sizes wall loss resulting from corrosion, erosion, wear, pitting, cracking, and baffle cuts. Olympus digital IRIS inspection technology is used extensively as a prove-up technique for remote field testing, magnetic flux leakage, and eddy current inspections. The system uses an immersion pulse echo technique in which a stream of water is used to spin a turbine containing the transducer. The turbine rotates a mirror, set at 45 degrees, to reflect the ultrasonic pulses radially into the tube wall. Reflections from the inner and outer walls of the tube follow the same path back to the transducer. The time interval between the first echo (the inner wall) and the second echo (the outer tube wall) measures the tube’s wall thickness. One hundred percent of the tube is inspected through a helical path, which is created when the transducer head traverses through the tube.

Application:
• Air Coolers
• Heat Exchangers
• Boiler Gen Bank tubes
• Feed Water Heaters

Remote Visual Inspection

(Boroscopy, RVI)

Remote Visual Inspection (Videoscopy) allows us to inspect the areas or objects which are hard to reach for human eyes without dismantling the machine or its surrounding structure. Videoscopy allows us to identify the discontinuities like surface defects, poor welding, pitting, corrosion, degradation, blockages, foreign material etc. before they cause any major problems.

Thermography

Thermography is a method of inspecting electrical and mechanical equipment by obtaining heat dissipating pictures. This inspection method is based on the fact that most components in a system show an increase in temperature when malfunctioning. The increase in temperature in an electrical circuit could be due to lose connections or a worn bearing in the case of mechanical equipment. By observing the heat patterns in operational system components, faults can be located and their seriousness evaluated. The inspection tool used by Thermographer is the Thermal Imager. These are sophisticated devices which measure the natural emissions of infrared radiation from a heated object and produce a thermal picture. Modern Thermal Imagers are portable with easily operated controls. As physical contact with the system is not required, inspection can be made under fully operational conditions resulting in no loss of production or downtime.

Potential applications include:
• Inspection of panels / electrical equipment
• Inspection of mechanical / rotating equipment

Phased Array Ultrasonic Testing

(PAUT)

An array transducer is simply one that contains a number of separate elements in a single housing, and phasing refers to how those elements are sequentially pulsed. A phased array system is normally based around a specialized ultrasonic transducer that contains many individual elements (typically from 16 to 256) that can be pulsed separately in a programmed pattern. These transducers may be used with various types of wedges, in a contact mode, or in immersion testing. Their shape may be square, rectangular, or round, and test frequencies are most commonly in the range from 1 to 10 MHz.

Long Range Ultrasonic Testing

(LRUT)

Pipelines and piping with limited external accessibility, e.g. at road crossings, buried |pipe, insulated pipe, overhead piping with limited access or other barriers to inspection could conventionally only be examined with very high and costly effort. Long Range Ultrasonic Testing (“LRUT”) service is fast and cost-effective. LRUT provides efficient screening of long pipe sections for corrosion and other damage mechanisms. From a single measurement location, LRUT emits guided waves to reach distant pipes and to those considered inaccessible via other means of inspection.

Advantages:
• Rapid screening with 100% coverage
• No need for a liquid couplant, which is necessary for conventional ultrasonic testing
• Maintenance cost reduction by not having to remove the insulation or coating

Helium Leak Testing

(LRUT)

Helium is the best choice of tracer gas to find leaks for a number of reasons. It is non-toxic, inert, non-condensable, non-flammable and not normally present in the atmosphere at more than trace amounts (5 ppm). Due to its small atomic size, helium passes easily through leaks. The only molecule smaller than Helium is Hydrogen which is not inert. It is also relatively inexpensive and is available in various size cylinders.

Applications:
• Quality control of production parts and assemblies using helium leak detectors can help assure the integrity of your production process

High Temperature Hydrogen Attack

(HTHA)

High temperature hydrogen attack (HTHA) is observed in steels exposed to temperature above 200 °C. At high temperature atomic hydrogen diffuses in steel. This hydrogen reacts with carbon of steel and forms CH4. The methane so formed bubbles at grain boundary and forms voids at grain boundary. (MC + 4H = M + CH4) These bubbles exert pressure and also coalesce resulting in to fissures. The growth of voids and fissures weakens the metal and the fissures develop in to major crack. This reaction decarburizes the steel, produces micro cracks/fissures and lowers toughness of steel but not necessarily cause loss in thickness.

The procedure for testing is based on API 941 using different approaches like:
• Attenuation measurement
• Velocity measurement
• Spectral analysis
• Analyzing back scattered signals
• Testing weld joints and HAZ using high frequency shear wave ultrasound
• Advanced ultrasonic testing like Phased array and TOFD

Visual Testing

(VT)

Visual testing (VT) is the oldest and most common nondestructive testing (NDT) techniques. It is typically the first step in the examination process to inspect a variety of product forms including castings, forgings, machined components and weld elements. Compared to other techniques, visual testing is low in cost and easy to apply, and often eliminates the need for further types of testing. Some of the industries that use VT include structural steel, automotive, petrochemical, power generation, and aerospace.

Surface Eddy Current Testing

(SECT)

Advanced portable eddy current (EC) flaw detectors inspect metallic parts and perform highly reliable flaw detection of surface and near-surface defects. Eddy current probes generate magnetic fields that induce current that flows in a test piece influencing the magnetic field and magnitude and phase of voltage in the coil. Applications include the detection of surface or near-surface defects, alloy sorting, and the inspection of bolt holes.

Applications:
• Aircraft inspection for cracks and corrosion damage
• Material sorting
• Bolt-hole defect detection
• Heat exchanger examination to ASME code
• General static as well as dynamic eddy current tests
• Conductivity measurement options
• Coating thickness measurement options

Ultrasonic Testing

(UT)

Ultrasonic testing (UT) uses high frequency sound energy to conduct examinations and make measurements. Ultrasonic inspection can be used for flaw detection/evaluation, dimensional measurements, material characterization, and more.

Advantages:
• It is sensitive to both surface and subsurface discontinuities
• The depth of penetration for flaw detection or measurement is superior to other NDT methods
• Only single-sided access is needed when the pulse-echo technique is used
• It is highly accurate in determining reflector position and estimating size and shape
• Minimal part preparation is required
• Electronic equipment provides instantaneous results
• Detailed images can be produced with automated systems

Magnetic Particle Inspection

(MPI)

An extremely cost-effective method for the detection of surface and near surface flaws in ferromagnetic materials, MPI is primarily used for crack detection. Following magnetization, the specimen is covered with a detection medium (ferrous oxide particles), either dry or suspended in a liquid. Surface breaking flaws distort the magnetic field causing local magnetic flux leakage that attracts the detection medium producing a buildup that can be seen visually.

Dye Penetrant Testing

(DPT)

DPT is low cost method of detecting surface breaking flaws, such as cracks, cold laps, porosity etc. Dye penetrant is drawn into a surface breaking flaw by capillary action and excess surface penetrant is then removed; a developer is then applied to the surface, drawing out the penetrant in the crack and producing a surface indication. The technique can be applied to many non-porous clean materials, metallic or non-metallic.

Advantages:
• Rapid screening with 100% coverage
• No need for a liquid couplant, which is necessary for conventional ultrasonic testing
• Maintenance cost reduction by not having to remove the insulation or coating

Radiography Testing

(RT)

A well-established NDT technique, radiography uses gamma-rays or x-rays to produce the image of an object onto film. The source of radiation is either an x-ray tube, which is normally described by the electrical voltage across the x-ray tube with the higher the voltage the higher the penetrating power of the radiation or a sealed source of radioactive material emitting gamma-rays: iridium 192, cobalt 60, selenium 75, ytterbium 169. Applications include wall loss detection and sizing in pipes and plate through to manufacturing defects in welds, forgings castings etc.

Advantages:
• Rapid screening with 100% coverage
• No need for a liquid couplant, which is necessary for conventional ultrasonic testing
• Maintenance cost reduction by not having to remove the insulation or coating

Positive Material Identification

(PMI)

It has been a long-established fact that a minor mix-up in the material could result in a major mishap and huge financial losses for the user. In order to prevent this from happening, all quality conscious project managers are increasingly prescribing Positive Material Identification (PMI) at each stage of plant commissioning. Mix-up can be at the vendor's end, during storage at the user end or at the time of actual fabrication. Thus, if PMI exercise is done at all these levels, a 100% confidence can be built up as far as material mix-up is concerned.

Applications:
• Inspection of panels / electrical equipment
• Inspection of mechanical / rotating equipment

Hardness Testing

(HT)

The Leeb Rebound Hardness Test (LRHT) is one of the four most used methods for testing metal hardness. This portable method is mainly used for testing sufficiently large workpieces (mainly above 1 kg). It measures the coefficient of restitution. It is a form of nondestructive testing.

Advantages & Applications:
• The assembled machinery and permanently installed parts
• Die cavity of molds
• Heavy work pieces
• Failure analysis of pressure vessel,steam turbo-generator set and otherequipment
• Narrow testing space where work pieceInstalled
• Bearings and other parts
• Case which require the test result with normalizedoriginal recording
• Material identification of the metal materialwarehouse
• Quick tests of large range and multipoint measuringpositions of heavy workpiece

Oxide Scale Measurement

(OSM)

The very high temperatures found inside steam boilers (in excess of 1500 °F (800 °C) can cause the formation of a specific type of hard, brittle iron oxide called magnetite on the inside and outside surfaces of steel boiler tubing. At very high temperatures, water vapor will react with the iron in the steel to form magnetite and hydrogen. The speed of this reaction increases with temperature. Oxygen atoms will diffuse inward through the magnetite layer, and iron atoms will diffuse outward, so the scale continues to grow even after the tube surface is completely covered.

Holiday Testing

(Spark Test)

A holiday test is an inspection method used to detect discontinuities in painted/coated surfaces using specialized tools and equipment. These tools, called holiday detectors, are portable devices that are swept across the coated surface. Holidays tests work on the concept of electrical conductivity. Metal substrates are excellent conductors of electricity, and therefore allow current to flow through them. On the other hand, many coatings are poor conductors of electricity and resist the flow of electricity. Using this principle, holiday tests use instruments to locate flaws in anticorrosive paints and coatings. During holiday testing, a ground wire and probing electrode are attached to the same power source. The ground wire is clamped to the specimen being tested while the probe is swept across the surface of the metal substrate. If the probe comes into contact with a coating discontinuity, the exposed metal completes the electrical circuit between the electrode and the grounding wire, resulting in a flow of electricity. This electricity shows up on an indicator, alerting the equipment operator of the defect.

In-Situ Metallography

(Replica)

Performed as an NDT service, In-situ Metallography determines in-service degradation of critical components of process plants operating under high temperature, high-pressure or corrosive atmosphere. Our Metallurgists have vast experience in the interpretation of microstructures. More than 10,000 replica microstructure interpretations have been carried out and captured in our database. The databank so generated contains extensive information on the microstructures of parts & components from various plants that have been captured over the course of several years of services. The database also includes rare collection of records of various microstructural damage for industries such as power, oil and gas, refinery, petrochemical, fertilizers, and other process industries. The In-situ Metallography team is highly skilled in the art of replica preparation. We have custom-developed special purpose on-site / field surface preparation & polishing devices & techniques which assist to enable metallographic polishing in difficult locations and allow the field technicians' team to carry out high quality replication even on warm components.

The In-situ metallography is performed for following areas:
• To find out in-service degradation of critical components of the process plants operating under high temperature /high pressure/ corrosive atmosphere
• Damage assessment of fire affected equipment of the plants
• Microstructural survey for critical components viz., Boilers, Pipelines, Reactors and Vessels for condition monitoring / health assessment
• To develop a data bank of critical components for equipment of process plant by periodical monitoring for preventive maintenance and planning for inventory control
• To provide suggestions on the welding of components of process plants
• To check the quality of the microstructure of components for intended service before put in to use