NON DESTRUCTIVE TESTERS LIMITED - A STOW CERTIFIED COMPANY

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RADIOGRAPHIC TESTING (RT)

This method is widely used to examine for subsurface discontinuities (such as voids, porosity, inclusions and cracks, etc.) in castings and weldments in a wide range of materials, by using the technique of radiographic exposure and interpretation of radiographic film. The interpretation of radiographic film requires knowledge of not only welding and welding discontinuities, but also of the acceptance criteria of the various codes and standards used in the industry. 

At NDTL our ASNT Level II Radiography Technicians have extensive knowledge and experience in performing these exposures safely, and are certified to interpret these films to the required codes and standards. NDTL also has a certified Level III on staff.

MAGNETIC PARTICLE EXAMINATION (MT)

Magnetic Particle Inspection (MPI) is a non-destructive test method for the detection of surface discontinuities in ferrous materials. Sub surface discontinuities can be detected but to a limited degree. The test method involves application of a magnetic field externally or applying electric current through the material which in turn produces magnetic flux in the material. Simultaneously, visible ferrous particles are sprinkled or sprayed on the test surface. 

The presence of a surface or near surface discontinuities in the material causes distortion in the magnetic flux which in turn causes leakage of the magnetic fields at the discontinuity. The magnetic particles are attracted by the surface field in the area of the discontinuity and adhere to the edges of the discontinuity appearing the shape of the discontinuity. 

NDTL offers a range of portable units designed for reliable and efficient testing.

ULTRASONIC TESTING (UT)

Ultrasonic testing is another method of non destructive testing where a transducer applies ultrasonic pulse waves in the frequency range of 0.5 to 10MHz in the material and the time of flight of the ultrasonic waves is measured from the initiation time to the return of the reflection to the transducer. Any change in acoustic impedance produces an ultrasonic reflection or echo. 
This property of the ultrasound is used to identify the material wall thickness and any internal discontinuities in material. 

Ultrasonic testing is a very sensitive test method for detection of embedded discontinuities. Ultrasonic testing is faster and more economical as compared to radiographic examination and requires a trained and experienced operator. The common applications of ultrasonic testing are wall thickness measurement, corrosion mapping, lamination testing, flaws in welds, castings, forgings and other wrought products. 

NDTL offers a range of high quality, accurate and calibrated portable Ultrasonic Testing equipment for thickness and flaw detection applications.

LOAD TESTING (LT)

Maintaining a high-level of safety for the operations of cargo handling equipment is of critical importance to general industry. Load testing is generally performed on all cargo carrying units, baskets, containers, bins, skids, equipment packs and all other equipment in need of certification before  transportation by lifting cranes, forklifts, etc… to determine the Safe Working Loads and Maximum Gross Weight limits.

LIQUID PENETRANT EXAMINATION (PT)

Dye Penetrant Inspection also known as Liquid Penetrant Inspection or Penetrant Test (PT) is a fast, economical and widely used non destructive test method to detect surface-breaking discontinuities in all non-porous materials (metals, plastics, or ceramics). 
Penetrant testing is based upon the principles of capillary action where liquid penetrates into a cavity. Penetrant testing is performed by cleaning the test surface thoroughly, applying colored or fluorescent penetrant, allowing penetration time and removal of excess penetrant followed by application of developer (dry or liquid form). 

The developer assists to draw penetrant out from the surface breaking discontinuities. 
After developer dwelling the test surface is examined for bleed out under natural light or black (UV) light (depending on the type of penetrant).  Fluorescent Dye Penetrant Inspection (FDPI) is the most sensitive test method.

Non Destructive Testers Limited provides both Visible and Fluorescent Penetrant Examination Methods.

Borescope - A borescope is an optical tool used to view areas that would otherwise not be visible. A borescope is inserted into the item being evaluated without destroying the item of interest.

Phased Array - Phased Array Ultrasonic Testing (PAUT), also known as phased array UT, is an advanced non-destructive inspection technique that uses a set of ultrasonic testing (UT) probes made up of numerous small elements. Each of these is pulsed individually with computer-calculated timing to create the phased aspect of the process, while the array refers to the multiple elements that make up a PAUT system.

Post Weld Heat Treatment - Post weld heat treatment (PWHT) is a term that refers to any heat treatment that is applied to a material after welding. The process is often used to improve the properties of the weldment. In most cases, the goal of PWHT is to increase the resistance of the material to brittle fracture by relaxing residual stresses which can occur in welds due to restraint by the parent metal during weld solidification. When these residual stresses combine with normal load stresses it is possible that they may exceed the material's design stresses which can cause weld failure.

PWHT can also be used for hardness reduction and material strength enhancements among other things. The extent of relaxation of the residual stresses depends on the material type and composition, the temperature of PWHT and the soaking time at that temperature.

NDTL provides certified personnel and equipment for both Pre-heat and Post weld heat treatment services.

Pre Heat

This is the process whereby metal is heated to a pre-determined temperature before engaging in the welding process.

The purpose of preheat:-

• Reduce the risk of hydrogen cracking
• Reduce the hardness of the weld heat affected zone
• Reduce shrinkage stresses during cooling and improve the distribution of residual stresses.
• NDTL provides this service by use of Heating consoles and thermal ceramic heating pads.

Holiday Detection - Holiday testing is a non-destructive test method applied on protective coatings to detect unacceptable discontinuities such as pinholes and voids. A Holiday test or Continuity test is performed by applying voltage (connected in series with an LED or noise-producing component such as a piezoelectric speaker) across the chosen path. The testing is usually performed on transmission pipelines, tank interiors, chemical storage vessels and buried structures because of the importance of maintaining adequate coating protection in aggressive service environments. NDTL provides a range of units to perform Low Voltage holiday detection on thin film coatings and High Voltage holiday detectors for thicker coating applications.

Brinell Testing - This method of testing is used to examine and assess the integrity of the surface of metals by measuring the resistance to deformation. The term hardness may also refer to resistance by bending, scratching, abrasion or cutting. This procedure is used to determine the hardness of a material by accurately measuring the diameter of an indentation made on the surface by using a Brinell Hardness test machine applying a specific force and measuring the resultant indentation. NDTL provides portable and easy to use Brinell Hardness test equipment for general industry applications.

Infrared Thermography - Infrared Thermography inspection testing is essentially a non-invasive, non-destructive inspection process that uses temperature sensing scanners. Infrared testing is used to locate and document thermal anomalies (hot spots). These infrared devices gather temperature signatures that lie beyond the range of visible light. Analysis of this data will help you detect a wide range of problems in building systems and structures, including moisture intrusion, missing or damaged insulation, overloaded circuits, faulty wiring, loose electrical connections and construction defects and also to identify other potentially dangerous situations which can in turn cause failure and downtime of plant and equipment.

IRATA Rope Access - Rope Access is defined by the use of ropes and specialized hardware as the primary means to gain access to and from the work place and support for workers. Rope access technicians descend, ascend, and traverse ropes for access and work while suspended by a harness or a work seat. The support of the rope should eliminate the likelihood of a fall altogether. Rope access workers use a back-up fall arrest system in the unlikely failure of their primary means of support. This redundant system is usually achieved by using two ropes - a working line and a safety line. The main advantage of using rope access methods mainly lies in the safety and speed with which workers can get to or from difficult locations and then carry out their work, often with minimal impact on other operations and the nearby area. IRATA International is the governing body responsible for rope access systems. Non Destructive Testers Ltd provides a wide range of IRATA Technicians and IRATA Rope Access Services; some common services provided include:

IRATA Level III supervisors and Level II & I Technician

IRATA UT Inspections

IRATA MT/PT Inspections

IRATA NACE Level I, II & III Inspectors

IRATA API 510/570/653 Inspectors

IRATA CWI Inspectors

IRATA Infrared Thermography  

IRATA Blasting & Painting

Positive Material Identification - Positive Material Identification (PMI) is the identification and chemical analysis of various metal alloys through nondestructive methods. 

PMI is employed for the following:

a.  when a sample cannot be cut for routine testing,

b.  when a mixed lot is suspected,

c.  when material identification/documentation has been misplaced,

d.  NDTL performs these checks by use of portable handheld units.

Vacuum Box - Vacuum box testing is a non-destructive examination used when trying to locate through thickness leaks on seam welds and adjacent sheeting material. A vacuum box and a vacuum pump create a high or low pressure vacuum while a bubble forming solution is applied to the test area. The bubbles indicate leaks visible within the created pressure envelope.

Items tested are as follows:

a.  Lap welds, butt welds, and shell to annular welds

b.  Piping systems and pressure vessels

c.  Tank bottoms

d.  Objects on which a pressure differential can be created across the area to be examined

Cathodic Protection - Cathodic protection is one of the most effective methods for preventing corrosion on a metal surface. Cathodic protection is commonly used to protect numerous structures against corrosion, such as ships, offshore floaters, subsea equipment, harbours, pipelines, tanks; basically all submerged or buried metal structur

Adhesion Testing - When an adhesive is bonded to an item or surface, numerous physical, mechanical and chemical forces come into play, which may have an effect on each other. These need to be tested before a product can be used.

QA / QC - We provide a wide range of personnel to adequately provide Quality Assurance / Quality Control services for the following activities:

a.  Welding Procedure Qualification / Welder Qualification – CWI and CSWIP Inspectors

b.  Fabrication and Welding – Certified Welding Inspectors (CWI), ASNT Level I and II Technicians, API 510, API 653 and API 570 personnel

c.  Fabric Maintenance – NACE Levels I, II and III and API certified personnel

d.  Plant Inspection (New Construction and Shutdowns) – CWI, NACE, API, ASNT Levels I,II and III

• Machine & Mechanical Testing
• Painting and Coating, 
• Statutory Inspections
• Plant Inspections
• Visual Inspection, 
• Welding Inspection, 
• API Inspection 
• UltraPipe Administrator