Our highly trained, experienced, and qualified technicians have the capabilities to assist your facility in conventional and advanced Non Destructive Testing.
Conventional NDT describes a process in which welds, materials or equipment can be examined for various types of discontinuities such as cracks, weld discontinuities, corrosion, or wear, that does not require the destruction of the component being tested. Advanced NDT has much the same process but compared to more conventional methods these tend to use more advanced equipment and complex processes.
Browse through the service listing below to read more about our expertise.

Radiographic Testing (RT) is a non destructive testing method that uses either x-rays or gamma rays to examine parts of equipment for flaws or damage. The type of radiation chosen is based on several factors such as the thickness and density of the material it’s made of. RT can be used for examining castings, pressure vessels, and valves, and heavy wall vessel inspection, among other things. It is the primary method used for determining weld quality during construction of pipelines, flow lines, meter stations and compressor facilities.

All operators of radioactive sources at GQI Ltd. are trained and qualified by PCN and the British Institute of NDT. The licensing body for Radioactive materials are the RPII which are part of the EPA.

  • it is highly reproducible
  • it provides a permanent record of the result
  • it works on a wide variety of material types
  • little surface preparation is required

Magnetic Particle Testing (MT) is a non destructive examination technique which is used for the detection of surface or near surface discontinuities in ferrous materials. The process involves inducing a magnetic field in the material, and the principle that the lines of force are forced out of the material when they encounter discontinuities perpendicular to those lines such as a crack. These excluded lines of force can be detected by using a highly attractive iron powder to form indications of the discontinuities.

MT can be performed on any ferromagnetic material that can be accessed and submitted to a magnetizing current. This method is a valuable tool for the inspection of welds and base metal in pressure vessels, tanks, piping, lifting components, structural steel and other items as applicable.

  • Can be highly portable and less expensive
  • Is highly sensitive in fluorescent applications
  • Can be used at high temperatures
  • Is not limited by specimen size or configuration

Dye Penetrant Inspection, sometimes simply referred to as Penetrant Testing (PT),  is one of the most reliable methods when seeking to detect discontinuities open to the surface on a wide array of materials. PT is capable of detecting several different types of surface defects in non-porous materials. When performed in accordance with a properly prepared procedure, liquid penetrant is capable of detecting very fine surface discontinuities not visible to the naked eye.

  • Field applications are highly portable
  • The application is inexpensive
  • Has high sensitivity
  • Minimal training and experience hours are required

Ultrasonic Testing (UT) is a method of examination that involves the use of high frequency sound waves to detect flaws in components and welds. UT can also be used to measure the thickness of materials, which is a common way of detecting metal losses from corrosion.

The process works by having a transducer generate an ultrasonic sound wave which travels through the material until it encounters a surface; this causes a part of the sound wave’s energy to be reflected back to the transducer

  • Capable of detecting not only surface flaws, but sub-surface flaws as well
  • It has superior depth of penetration compared to other methods
  • It is very accurate at measuring discontinuity size and shape
  • The results of the scan are instantaneous

In order to comply with national standards which apply collectively to codes, specifications, and recommended practices, it is mandatory that welding procedures be written and qualified in accordance with the applicable standard.

GQI ltd have CSWIP & PCN  qualified inspectors who can provide a service to test and qualify welders to the requirements of ASME and EN ISO 15609. Also to provide welding inspectors to oversee project compliance to ASME and EN standards across a wide range of industries including oil & gas, power generation pharmaceutical etc.

In general terms, surveying for corrosion starts with a quantification process. It is important to locate what type of breakdown is occurring, to what severity and in which locations. This is a visual process, which is aided by the experience of our GQI Surveyors and the use of relevant NDT methods.

The second, and more important part of the surveying for corrosion process, is that of developing an understanding of the failure mechanism and why it is occurring. It is important to be able to answer the questions: why?, and how? Answers to these questions will enable the experienced surveyor to be able to put some kind of time-scale on the process and to be able to predict how soon catastrophic failure will occur.

  • Develop a cost effective maintenance and repair strategy
  • Helps avoid expensive repairs and steel renewals
  • Clear pre-purchase assessments of equipment can be made
  • Renew or repair decisions can be made on an informed basis

GQI offers a comprehensive Storage Tank inspection service individually tailored to suit client’s specific requirements. Inspection packages range from basic visual inspection to full engineering assessments with formal reporting detailing the suitability of the tank to remain capable of current service. Tank integrity including remaining life is estimated from engineering calculations based on critical data collected by a range of NDT techniques and survey results.


Visual Testing (VT) is a method of examining for surface flaws on a piece of material or equipment by assessing it visually. It is the oldest form of testing and remains one of the most reliable to this day. No examination is more valuable than the one performed using the eyes of an experienced inspector. In fact, many other NDT methods simply provide an enhanced or volumetric view for the eyes of the inspector to analyze.

Direct visual examination is the key to ensuring welding operations are performed in accordance with the governing codes and procedures. Visual examination is performed during in-service examinations of piping, vessels, tanks, boilers, and other equipment to detect a wide range of conditions and may be supplemented by mechanical measurements, photography, magnification, or chemical etching or response methods.


Flow accelerated corrosion (FAC) in piping is a widespread problem in all types of plants and, if left undetected, can result in personal injury, equipment damage and plant downtime.

FAC is the dissolution of the normally protective oxide layer that is present on the surface of carbon and low alloy steel when exposed to flowing water or wet steam under specific conditions. It causes wall thinning in piping, vessels and other components, and if not detected in time, can lead to leaks or instantaneous ruptures. In some instances, flow accelerated corrosion can cause major failures.

The serious problems that FAC can cause mean that it is vital plants develop a programme to minimise FAC damage.

To address the issue, GQI has developed a comprehensive approach to identifying the early signs of FAC in piping and locate high risk areas. This can reduce the risk of serious plant failure with damaged components and ensure continued plant safety and reliability. A range of NDT methods are utilised in the process.



The protection provided by the coating systems is usually shorter than the expected service life of the structure,

The design of a protective system for any given structure will depend largely on the function and anticipated life of the structure, the general and local nature of the environment, and the type and degree of protection and subsequent maintenance requirements.

Coating Integrity Inspection of equipment and plant coating systems and asset condition is initiated to determine the need for maintenance and repair. The results of in-service inspection are invariably linked to maintenance budgets, thus there is a continual striving for balance between the two extremes. GQI’s range of experience means that our coating inspectors can survey, assess and document your assets’ integrity on your behalf in a competent and proficient manner.


Remote Visual Inspection (RVI) is an indirect NDT technique that employs the use of: videoprobes, videoscopes, video borescopes, remote operated pan tilt zoom (PTZ) cameras, CCTV camera systems, robotic crawlers, remote operated vehicles (ROVs) and a wide array of specialized tooling to deliver clear, concise remote visual data.  This minimally invasive inspection technique is ideally suited for hostile environments unsafe for human intervention or in areas of inaccessibility.

GQI’s remote visual inspection team safely deploys inspection cameras into difficult to reach or dangerous areas to deliver clear, concise visual data relating to asset condition and plant operability. At GQI we have carried out internal camera inspections on Main headers, high purity lines, gas lines, vessels, sewage lines etc.. All RVI activities are supported with comprehensive detailed reports that include all relevant data points, images, and video recordings.