This week, 7 technicians from Ontario and Nova Scotia participated in non-destructive testing at the Hercules Training Academy in Dartmouth, NS. They focused on learning and improving Magnetic Particle and Liquid Penetrant Inspections, two of the most commonly-used forms of non-destructive testing.
Non-destructive testing uses various methods to test, inspect and evaluate defects in various materials or mediums without compromising the integrity of the product.
For example, a chain sling can be inspected to determine what internal material characteristics are there, what’s defective and what’s different than is supposed to be. This allows materials and equipment to be serviceable after testing.
Non-destructive testing is important as it lets us find defects on equipment and material workers are actually using (called in-service testing) and ensures products and equipment in use are safe for the public and those using it.
Before a product is in use, (the fabrication and manufacturing process) a technician will use non-destructive testing to control the manufacturing process, manage quality and lower production costs. When something is being constructed, non-destructive testing is used to protect and maintain material quality during the joining process, fabrication and erection phases.
Destructive Testing and Non-Destructive Testing: What’s the difference?
During destructive testing, small samples of the material is tested instead of what’s actually being used by the public or a worker. For example, a sample of a welded piece from production may be tested to determine it’s physical structure—things like ductility, yield, ultimate tensile strength, fatigue strength, impact strength and fracture toughness.
When testing is over, the product is obviously unserviceable. While destructive testing is essential and often useful, (when mass-producing something, for example) this isn’t financially realistic for many industries, or products where a limited amount is manufactured. This is where non-destructive testing steps in.
Magnetic Particle (MP) Testing
Magnetic Particle testing uses one, or multiple magnetic fields to find discontinuities on and near surfaces of ferromagnetic materials. The magnetic field is applied with either a permanent or electromagnet.
If the magnetic field finds an issue (discontinuity) that intersects directly with the magnetic field, it creates magnetic flux leakage. Magnetic flux lines don’t travel well in air—coloured ferromagnetic particles are applied, spaces in the air are reduced, which creates a visible indent on the surface. Magnetic particles are sometimes dyed with fluorescent dye that glows under a UV-light.
Yokes, prods, coils, ‘wet’ benches and central conductors are techniques used to perform magnetic particle inspection.
Liquid Penetrant (LT) Testing
When a highly-fluid, or viscose liquid is applied to the surface, it penetrates fissures and spaces that can access the surface. The extra liquid is then removed and what is left in the void flows back out. This creates a mark which shows where defects or issues may be. Liquid penetrants may also be visible with a UV or black light. It’s important that the testing surface is clean and clear of any materials or liquid that could compromise testing (anything that could block the liquid from entering cracks and voids).
The liquid sits on the surface for awhile, during what’s known as the ‘penetrant dwell time’. After this, the penetrant is removed and a developer is applied to the surface—this makes voids appear clearer, and the object is then visually inspected.
Liquid penetrants used during this process include solvent removable, water-washable and post-emulsifiable penetrants.
Hercules: Dedicated to Learning
It’s important to Hercules SLR to offer training, education and opportunities to learn.
Keeping technicians up-to-date with the latest emerging technologies and skills are one of our core values—it allows us to provide the best, service for our customers and clients.
We’ll help you regulate and improve the safety of your securing, lifting or rigging devices and bring them to industry standards, in dynamic or static settings. We’ll also supply full certification for your equipment to prove it complies with both provincial and national safety standards.
All Hercules SLR customers have access to our web-based certificate tracking system, CertTracker®. Our CertTracker® system helps you maintain inspection records, provide inspection notice due dates and schedule service times. We can ensure your worksite equipment stays certified.
Hercules SLR offers both destructive and non-destructive equipment testing services—click here for more information.
References: https://www.asnt.org/MinorSiteSections/AboutASNT/Intro-to-NDT.aspx