Non-destructive testing

Non-destructive testing (NDT) encompasses an extensive range of tests that are used to determine the integrity and properties of a specific material, product or system without damaging the test subject. 

These techniques are widely believed to be essential for quality regulation. They ensure that important structures like pipelines, mining plants and even medicines are durable and long-lasting.

Value of non-destructive testing

Non-destructive testing is considered to be a very valuable process. It does not affect the integrity of the item being investigated and can therefore save both time and money when planning, evaluating and troubleshooting particular projects.

These important tests are conducted in a wide variety of ways – see examples below – and can detect defects or damage both on the surface of an item or within the component itself.

The presence of potential flaws in essential items could result in the integrity of whole systems being called into question and also increase the risk of on-site failure. Early detection of any flaws through non-destructive testing is therefore critical in preventing accidents and shutdowns.

Non-destructive testing techniques are regularly found in many different industries, such as:

• – Forensic Engineering
• – Petroleum Engineering
• – Electrical Engineering
• – Civil Engineering
• – Aeronautical engineering
• – Medicine
• – Art

Many different national and international trade associations are in existence and work to promote the industry, share knowledge and develop international standardised methods and training. These include the American Society for Non-Destructive Testing, the Non-Destructive Testing Management Association, the International Committee for Non-Destructive Testing, the European Federation for Non-Destructive Testing and the British Institute of Non-Destructive Testing.

Special Piping Materials and non-destructive testing

Special Piping Materials is qualified to carry out many non-destructive tests in-house, therefore saving clients both time and money. These are tests such as Dye-Pen Inspections and Impact Testing. We have highly-trained, specialist ASNT and PCM qualified personnel at all our offices around the world meaning we can carry out these tests quickly and cost-effectively on any material.

The vast amount of stock that we carry across the global is tested in accordance with respective ASTM standards, ASME standards and international specifications such as Norsok MDS, Shell MESC & Exxon Mobil.

As a globally-focused business, we appreciate that different clients have different requirements and specifications when it comes to their products. This means that some testing needs to be outsourced. We have subsequently got a worldwide network of trusted and highly-qualified testing partners who we subcontract for any further testing requirements.

To safeguard the quality of the work, we only use NAMAS/UKAS approved test houses. All these providers are also qualified to ISO17025 which ensures that they are both authorised to undertake the work and are independent in their evaluations.

Advantages of non-destructive testing

Non-destructive testing is obviously only one type of testing in heavy industries, with destructive testing also being a common choice.

Destructive testing does have its merits, mainly that it is able to determine the physical properties of materials such as impact resistance, ductility, yield and ultimate tensile strength, fracture toughness and fatigue strength. However, discontinuities and differences in material characteristics are more generally thought to be more effectively found by non-destructive testing.

Non-destructive testing has many advantages:

• – The results are immediate: This is especially true if they are carried out by a supplier like Special Piping Materials as we are able to test the material as soon as it arrives in our warehouses.
• – It is cost-effective: There is no need to be extra material to destroy through testing.
• – Gives confidence: Because the actual items are being tested, end-users have the certainty that they meet the specification required and can withstand the environments that they are being put into.

Examples of non-destructive testing 

There are many different types of non-destructive tests, so below are a few examples. All of these can either be carried out internally at a Special Piping Materials office or through one of our trusted testing mill partners.

• – Dye Penetration Inspection: This is a consistent, reliable, and cost-effective method of finding surface flaws in non-porous materials such as metals, plastics or ceramics. It works by a dye being applied to an item, the excess removed and then it is given time to seep out of any discontinuities in the material, consequently highlighting any issues.
• – Magnetic particle inspection: This method is used to check for surface and ‘near-surface’ flaws in ferrous materials. It relies on magnetic field to produce results and therefore works best on ferrous materials, like nickel, iron, cobalt, and some alloys. Because this method relies on a magnetic field to produce results, it works best on ferrous materials, like nickel, iron, cobalt, and some alloys.
• – Ultrasonic inspection: Ultrasonic testing manipulates sound waves to detect cracks and defects in certain items and can also be used to determine the thickness of an area, such as a wall of a pipe. The results from this test are often clearly defined images and can show potential flaws that are deeper than surface level.
• – Thermal Infrared Testing:This evaluates and measures differences in temperature on the surface of a material using thermal imaging devices. Very small changes in temperature indicate that there are cracks or discontinuities in the material.
• – Ferrite Testing:This fast and inexpensive test is an accurate way to measure delta ferrite levels in both austenitic and duplex stainless steels. It checks to see if the ferrite content is too low or high. Too low could mean than the material is susceptible to hot cracking or solidification cracks whereas if it is too high it could lead to the item losing its ductility, toughness, and ability to resist corrosion.
• – Visual inspection:Non-destructive testing methods don’t necessarily need to use high-tech machinery. Visual Inspection is an important part of the process and involves high-qualified and trained individuals examining products to check for specific characteristics and attributes. For example, visual inspectors are likely to look for any obvious cracks or corrosion, as well as potential banding, surface discontinuities or even problems with material consistency.

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