Safety is the greatest concern when you’re welding steel for use in materials handling and personnel operations. One small flaw – even if it’s too small to see – can be fatal.
This is why best practice demands that every weld on a lifting point should be tested. There are various ways to test the penetration and effectiveness of a weld, but we adhere to ISO 9934.
ISO 9934 specifies how magnetic particle testing (MPI) can be used to verify the quality of a weld. This is an important part of good welding practice, and it’s crucial in ensuring the safety of finished products.
In this article, we’ll discuss why magnetic particle testing is important, and some of the most common welding faults in materials handling equipment.
The Safety Risks of Poor Welding
Did you know that in 2022, 24 workers died in the Australian construction industry due to work related causes?
You might remember that in September, 2018, a man was killed and two others were injured after a tub of concrete fell from a crane at a construction site in Melbourne’s east.
In this incident, a kibble of concrete fell into the pit. One worker was killed, others were injured, and two men working in the pit were submerged in concrete. It was a horrific accident. In response, Union Leader John Setka uttered the words:
“No one should go to work and die.”
In 2019, Weld Australia CEO Geoff Crittenden discussed the importance the role welding plays in public safety:
“The entire lifecycle of the welding process – from design through to inspection – must consider all aspects that could affect weld quality, and therefore public safety.”
Comments from both industry leaders are an indicator of where the industry is at – it’s time we started putting safety ahead of convenience.
What is Magnetic Particle Inspection?
Magnetic particle inspection (MPI) is a testing method that can detect faults in a weld by passing a magnetic current through it. The process works on ferromagnetic metals, including steel, iron and some alloys.
Defects are indicated by disruptions in the magnetic flux. This is detected using ferrous particles that align themselves to the magnetic field.
This is crucial in maintaining safety standards when welding lifting equipment for cranes. MPI is non-destructive and very accurate, so it’s one of the simplest ways to verify the quality of a weld.
Common Flaws Detected by MPI Testing
MPI testing can detect most common flaws in welding. Bremco uses MPI to detect a variety of common defects in welds, including:
- Cracks (these can be hot cracks, cold cracks, and crater cracks)
- Undercuts
- Porosity
- Incomplete fusion
- Slag inclusion
- Incomplete penetration
- Spatter
Through the process of MPI testing, these welding defects reveal themselves quickly. The method also gives us a precise location that can be used to rectify the defect.
MPI testing is completed by a qualified agent who cleans the weld surface, magnetises it, pours an iron powder over it, and then observes where the powder may gather.
If a surface or subsurface defect is present, the lines of magnetic force will deform around it. This causes the iron powder particles to bridge the gap caused by the defect and give an immediate visible indication.
This image below demonstrates flux lines flowing past both a perpendicular and parallel defect, and flux leakage occurring around the perpendicular flaw. The presence of a surface or subsurface defect in the weld allows the magnetic flux to “leak” (since air cannot support as much magnetic field per unit volume as metals).
While there are alternatives to MPI testing, there are several obvious advantages to the practice. These include the efficient detection of both surface and subsurface defects, and that welds can be tested in difficult to reach or irregular locations.
ISO 9934-1 – Magnetic Particle Testing
The principles of magnetic particle testing are laid out in ISO 9934-1. Our inspectors adhere to the ISO standards to improve the consistency and quality of our products.
ISO 9934 provides guidelines on how to prepare a product for MPI testing, how to conduct the test, and how to interpret the results. The standard is recognised all over the world, as well as within Australia.
Each of our products is supplied with certification to show that MPI testing has been completed. That allows you to manage and verify the quality of your materials handling equipment.
Crane Lifting Products and Mag Particle Testing
The fact is that cranes and crane lifting attachments are essential and widely used for transferring goods in various industries. Tower cranes, mobile cranes, gantry cranes and overhead lifting facilities are engaged in Australian construction, manufacturing and marine industries. The use of cranes directly aids productivity and cuts timelines, yet the risk inherent in using cranes and crane lift attachments in complex operations is no joke. Crane accidents of any kind can and do result in catastrophic impacts on the safety of workers and the public.
This is why it’s important that each and every product such as a lifting beam or a crane spreader beam features a welded crane-lift eye has Mag Particle Testing (MPI testing) done. And why a 100% pass is the only passing level that we will accept before our product will be approved for dispatch. All crane lift product that features welded lifting eyes, such as crane lifting cages, crane man cages, crane lift bins and even general crane attachments (such as pallet hooks, spreader beams, lifting beams and even crane bulk bag lifters) are all required to meet Australian Standards, and should all be provided with a compliance certificate demonstrating the MPI Test result that has been carried out in accordance with ISO 9934.
What Makes Welding Good Quality?
We use MPI testing to verify the quality of load-bearing welds. This begs the question of “what is a good weld?” High quality welds demonstrate a few key characteristics:
- Full penetration – Welds should fully join two parts, right down to the joint’s root. Voids within the weld can weaken the joint and cause cracks or breaking. This can be tested with magnetic particle inspection.
- Smooth appearance – Good welds should be visibly smooth. There shouldn’t be any slag, spattering or roughness.
- Uniformity – Welds should appear uniform and have a consistent width along the length of the weld line. This ensures full penetration and reduces the likelihood of an internal void.
- Colouration – A good weld is largely colour-free. If the weld or the surrounding metal has discoloured to shades of purple or blue, it can indicate that excessive heat was used.
While welding is a skill, proper quality control ensures each weld is fit for purpose. Generally speaking, if you purchase materials handling equipment from an Australian supplier, you can trust the quality of the welds.
This isn’t necessarily true for welded products that are sourced from overseas. Weld testing and quality control is uncommon in many parts of the world. While the surface of the weld may appear sound, invisible voids and cracks may prove fatal.
This is an ongoing issue with our industry. The Australian steel industry has also been issuing warnings about the safety standards of steel products – including forklift and crane lifting equipment – that’s being imported from overseas.
Mag Particle Testing
Magnetic particle inspection (MPI) testing of welds is a very effective form of surface-examination that aids in detecting surface and shallow subsurface discontinuities, or flaws, in ferromagnetic materials such as iron or steel. This is achieved in a non-destructive way that allows for visual inspections to quickly and efficiently detect any weaknesses in the weld, which can then be evaluated and rectified.
The seven most frequent welding defects are listed most commonly as:
- Cracks (these can be hot cracks, cold cracks, and crater cracks),
- Undercuts,
- Porosity,
- Incomplete fusion,
- Slag inclusion,
- Incomplete penetration, and
- Spatter
Through the process of MPI testing, each of these welding defects (if present) reveal themselves quickly and clearly to a precise location. The testing is completed by a qualified agent who effectively cleans the weld surface, magnetizes it, pours an iron powder over it, and then observes if and where the powder may gather. If a surface or slightly sub-surface defect is present, then lines of magnetic force will deform around it, causing the iron powder particles to bridge the gap caused by the defect and give an immediate visible indication.
This image below demonstrates flux lines flowing past both a perpendicular and parallel defect,
and flux leakage occurring around the perpendicular flaw. The presence of a surface or subsurface defect in the weld allows the magnetic flux to “leak” (since air cannot support as much magnetic field per unit volume as metals).
Whilst mag particle testing is only one of several forms of testing that may be completed, there are several obvious advantages to the practice. These include the efficient detection of both surface and subsurface defects, and that welds can be tested even if in difficult to reach or irregular locations on the product.
Choose Quality Australian Made Crane Lifting Attachments From Bremco!
Bremco Metal Products takes great pride in the quality of our work, but we don’t just trust that our products look great. Every product we manufacture in our Australian workshop is subject to magnetic particle inspection.
When you purchase a Bremco product that features a welded crane-lift eye, you will be issued a copy of the MPI testing certificate demonstrating a 100% pass. This means you and your workers can rest easy knowing you’re safe.
We conduct MPI testing on every crane lift product that features welded lifting eyes, including crane lifting cages, crane man cages, crane lift bins and general crane attachments and more. Every tested unit is provided with a compliance certificate demonstrating the MPI Test result that has been carried out in accordance with ISO 9934.
You should expect nothing less!