Services

CWI | Penetrant | Radiography | Ultrasonic Testing | Magnetic Particle | PMI | Hardness Testing

 

NDT Inspection Services

 

 

CWI

  • Interpret drawings and other documents.
  • Verify that the base materials and consumable welding materials conform to the specifications and that the welding filler metals used are as specified for each base material or combination of base materials.
  • Verify that the welding equipment to be used for the work is appropriate for the use with the welding procedure and has the capability to meet the applicable requirements of the welding procedure.
  • Verify that the welding procedures are as specified and are qualified, and that the welding performed is performed in conformance to the applicable procedure.
  • Witness performance and testing of procedure qualification test assemblies, or supervise these activities when performed by outside agencies.
  • Verify documentation of procedure qualification test results.
  • Verify that welders, welding operators, and tack welders have been qualified in conformance to the applicable standards, and that they are qualified to use the welding procedures specified for the work.
  • Witness testing of the welder test assemblies and/or welding operator qualification test assemblies, or supervise these activities when performed by outside agencies.
  • Verify documentation of performance qualification test results.
  • Require requalification if there is evidence the welder’s or welding operator’s work does not conform to the requirements of the applicable standard.
  • Require requalification if the welder’s or welding operator’s qualification is not current.
    • AWS Certified Welding Inspector certificate.
    • Are familiar with: SMAW, SAW, GTAW, FCAW, GMAW welding processes
    • Are familiar with: VT, UT, RT, MT, PT testing processes

Penetrant

What is it?
Liquid (or dye) penetrant inspection is an extension of visual inspection used for detecting surface-breaking flaws, such as cracks, laps, and folds on any non-absorbent material’s surface.

How does it work?
The basic stages of liquid penetrant inspection are shown below. First, the surface is cleaned thoroughly to remove all traces of dirt and grease. A brightly colored or fluorescent liquid is then applied liberally to the component surface and allowed to penetrate any surface-breaking cracks or cavities. The liquid is soaked into the material’s surface for about 20 minutes. After soaking, the excess liquid is wiped from the surface and a developer applied. The developer is usually a dry white powder, which draws penetrant out of any cracks by reverse capillary action to produce indications on the surface. These (colored) indications are broader than the actual flaw and therefore more easily visible.

Penetrant testing:

  • Sample before testing.
  • Liquid penetrant applied.
  • Surplus wiped off leaving penetrant in crack.
  • Developer powder applied, dye soaks into powder.
  • View coloured indications, or UV lamp shows up fluorescent indications.

A number of liquid penetrant systems are used in industry. Fluorescent penetrants are normally used when the maximum flaw sensitivity is required. However, these penetrants must be viewed under darkened conditions with a UV lamp, which may not be practical. The most commonly used systems are solvent removable, or water washable, red dye systems, which typically comprise three aerosol cans – cleaning fluid, penetrant and developer. These systems are often used to check weld quality during fabrication.

Radiography

An NDT Inspection Services method for the detection of internal defects in castings, welds or forgings by exposure to x-ray or gamma ray radiation. Defects are found by differences in radiation absorption in the material as seen on a shadow graph displayed on photographic film or a fluorescent screen.

 

Ultrasonic Testing

Ultrasonic Testing, very short ultrasonic pulse-waves with center frequencies ranging from 0.1-15 MHz to 50 MHz are launched into materials to detect internal flaws or to characterize materials. The technique is also commonly used to determine the thickness of the test object, for example, to monitor pipework corrosion.

Ultrasonic testing is often performed on steel and other metals and alloys, though it can also be used on concrete, wood, and composites. It is a form of non-destructive testing used in many industries including aerospace, automotive, and other transportation sectors.

How it works
In ultrasonic testing, an ultrasound transducer connected to a diagnostic machine is passed over the object being inspected. The transducer is typically separated from the test object by a couplant (such as oil) or by water, as in immersion testing.

There are two methods of receiving the ultrasound waveform, reflection and attenuation. In reflection (or pulse-echo) mode, the transducer performs both the sending and the receiving of the pulsed waves as the “sound” is reflected back to the device. Reflected ultrasound comes from an interface, such as the back wall of the object or from an imperfection within the object. The diagnostic machine displays these results in the form of a signal with an amplitude representing the intensity of the reflection and the distance, representing the arrival time of the reflection. In attenuation (or through-transmission) mode, a transmitter sends ultrasound through one surface, and a separate receiver detects the amount that has reached it on another surface after traveling through the medium. Imperfections or other conditions in the space between the transmitter and receiver reduce the amount of sound transmitted, which reveals their presence.

At a construction site, a technician tests a pipeline weld for defects using an ultrasonic phased array instrument. The scanner, which consists of a frame with magnetic wheels, holds the probe in contact with the pipe by a spring. The wet area is the ultrasonic couplant that allows the sound to pass into the pipe wall.

Non-destructive testing of a swing shaft showing spline cracking

Features

Advantages

  1. High penetrating power, which allows the detection of flaws deep in the part.
  2. High sensitivity, permitting the detection of extremely small flaws.
  3. Only one surface need be accessible.
  4. Greater accuracy than other nondestructive methods in determining the depth of internal flaws and the thickness of parts with parallel surfaces.
  5. Some capability of estimating the size, orientation, shape and nature of defects.
  6. Nonhazardous to operations or to nearby personnel and has no effect on equipment and materials in the vicinity.
  7. Capable of portable or highly automated operation.

Disadvantages

  1. Manual operation requires careful attention by experienced technicians.
  2. Extensive technical knowledge is required for the development of inspection procedures.
  3. Parts that are rough, irregular in shape, very small or thin, or not homogeneous are difficult to inspect.
  4. Surface must be prepared by cleaning and removing loose scale, paint, etc, although paint that is properly bonded to a surface usually need not be removed.
  5. Couplants are needed to provide effective transfer of ultrasonic wave energy between transducers and parts being inspected unless a non-contact technique is used. Non-contact techniques include Laser and Electro Magnetic Acoustic Transducers (EMAT).
  6. Inspected items must be water resistant, when using water based couplants that do not contain rust inhibitors.

Magnetic Testing Services

Magnetic particle testing is a non-destructive testing method for finding imperfections on or just below the surface of ferrous metals. It is a quick and reliable technique for locating of surface cracks.

A magnetic flux is sent through the material. At the location of the imperfection a leakage field is formed. This attracts metal iron dust, which is sprayed onto the surface. The length of the imperfection can be determined very reliable. Magnetic particle testing does not indicate the depth of the imperfection. Acceptance criteria define whether or not the indication is non-acceptable (a defect) or not.

Magnetic particle testing can be used for all ferrous metals, such as carbon steel, low-alloy and cast iron. The main use of Magnetic particle testing is for welds and heat affected zones. It can be applied to relatively rough and dirty surfaces but flaw sensitivity is decreased for this. Fluorescent particles can be used when maximum sensitivity is required.

PMI Inspections

Positive Material Identification (PMI)
Refers to the identification and analysis of various metal alloys based on their chemical composition in nondestructive testing (NDT). Measurement results are shown in the form of elemental concentration in percentage or by specific alloy name such as SS316L or Inconel 625. PMI is a field-testing method made possible by the portability of most PMI analyzers. These instruments also can be used in the laboratory. Our Company uses XL3T 800 handheld XRF handheld analyzer.

The Growing Importance of Positive Material Identification
Because specifications for materials used in industries are increasingly more specific, the need for PMI testing has been steadily increasing for the past several years. Periodic plant maintenance or shutdowns are less frequent and consequently the materials used in the plant are in use longer. A wider variety of alloys that are indistinguishable to the eye are being used in individual plants. When facility staff replace components, they must be able to guarantee that the new part matches engineering specifications. Recent industrial accidents have cost the lives of workers and heightened the awareness of the need for accurate and comprehensive PMI inspections.

Examples of Where Positive Material Identification is Used
Today, many major oil companies require that every pipe, flange, connector, valve and welding seam in critical parts of the plant be measured to verify that materials match engineering specifications. Finally, global sourcing is another factor driving the need for PMI. Currently, metal buyers and suppliers are operating globally, and buyers need to verify the quality of the product they are receiving.

Hardness Testing

Our Company uses the EQUOTIP 3

The Equotip measuring principle is physically a rather simple, dynamic hardness test. An impact body with a hard metal test tip is propelled by spring force against the surface of the test piece. Surface deformation takes place when the impact body hits the test surface, which will result in loss of kinetic energy. This energy loss is calculated by velocity measurements when the impact body is at a precise distance from the surface for both the impact and rebound phase of the test. The permanent magnet in the impact body generates an induction voltage in the single coil of the impact device. The voltage of the signal is proportional to the velocity of the impact body, and signal processing by the electronics provides the hardness reading for display and storage.

Primary Industries

  • Metal production & processing
  • Automotive & transportation
  • Machinery & power plants
  • Petro-chemical, refineries
  • Aerospace & shipyard
  • Metal constructions
  • Testing services & laboratories