Most of our personnel are certified in three or more NDT methods, thereby offering more efficient and cost effective services. In the field of NDT, UNICO has done a considerable amount of work within a short period of time, both in the company and in the field. Due to quality of work, prompt service and capability to cater large volumes of work, NDT Services are regularly in demand by reputed clients. Our team is committed to providing a high quality, customer focused service to suit our client's requirements. We understand the need for a prompt response time to ensure costly downtime is minimized.

UNICO's conventional NDT services include:

Ultrasonic Thickness & Flaw Detection
Radiography (x-ray and gamma)
Magnetic Particle
Positive Material Identification
Visual Inspection (CWI, API 510, 570, 653; ANST)

Ultrasonic Testing (UT)
Ultrasonic inspection uses sound waves of short wavelength and high frequency to detect flaws or measure material thickness. It is used to test welds, castings and wrought products, e.g. rolled plate or forgings. Manual and immersion techniques are employed.

Manual testing involves sound waves (pulsed beams of high frequency ultrasound) transmitted via a hand-held transducer, which is placed on the specimen. A 'couplant' is used to enable the sound to pass from the transducer to the component under test. Any sound from the pulse that returns to the transducer (echo) is shown on a screen, which gives the amplitude of the pulse and the time taken to return to the transducer. Flaws anywhere through the specimen thickness reflect the sound back to the transducer. Flaw size, distance and reflectivity can be interpreted.

The immersion technique involves placing the component in a tank of water and passing the sound waves through the water into the component.

Because of its complexity considerable technician training and skill is required.

Radiographic Testing (RT)
Also known as x-radiography and gamma radiography. X-rays are produced by high voltage x-ray machines, whereas gamma rays are produced from radioactive isotopes such as Iridium 192 and Cobalt 60. The x-ray or gamma rays are placed close to the material to be inspected and they pass through the material and are then captured on film. This film is then processed and the image is obtained as a series of grey shades between black and white. Gamma sources have the advantage of portability which makes them ideal for use in site working.

X-rays and gamma rays are very hazardous. Special precautions must be taken when performing radiography. Therefore the operator will use these inside a protective enclosure or with appropriate barriers and warning signals to ensure there are no hazards to personnel.

Magnetic Testing (MT)
Also known as MPI (Magnetic Particle Inspection). It is a method that can be used to find surface and near surface flaws in ferromagnetic materials such as steel and iron.

The technique uses the principle that magnetic lines of force {flux) will be distorted by the presence of a flaw in a manner that will reveal its presence. The flaw (for example, a crack) is located from the "flux leakage", following the application of fine iron particles to the area under examination. There are variations in the way the magnetic field is applied, but they are all dependant on the above principle.

The iron particles can be applied dry or wet; suspended in a liquid, coloured or fluorescent. While magnetic particle inspection is primarily used to find surface breaking flaws, it can also be used to locate sub-surface flaws. But its effectiveness quickly diminishes depending on the flaw depth and type.

Surface irregularities and scratches can give misleading indications. Therefore it is necessary to ensure careful preparation of the surface before magnetic particle testing is undertaken.

Visual Testing (VT)
Also known as Visual Inspection, VT is the one NDT method used extensively to evaluate the condition or the quality of a weld or component. It is easily carried out, inexpensive and usually doesn't require special equipment.

It is used for the inspection of welds and other components where quick detection and the correction of flaws or process related problems can result in significant cost savings. It is the primary evaluation method of many quality control programmes.

VT requires good vision, good lighting and the knowledge of what to look for. Visual inspection can be enhanced by various methods ranging from low power magnifying glasses through to boroscopes. These devices can also be used with television camera systems. Surface preparation can range from wiping with a cloth to blast cleaning and treating with chemicals to show the surface details.

It can identify where a failure is most likely to occur and identify when failure has commenced. VT is often enhanced by other methods of inspection which can identify defects that are not easily seen by the eye.