Weld Failures: What Causes Faults and How to Detect Them With Non-Destructive Testing
Whether you realize it or not, your business or industry is supported somewhere by materials that have been welded together. Welding has existed since the Bronze Age, creating billions of tools and structures for individuals over thousands of years. Welding technology has come a long way since then and is considered one of the most efficient ways to join two materials together.
In British Columbia, Alberta, and Saskatchewan, a common utilization of welding is often demonstrated in the oil and gas industries. Metal piping is typically joined together by bonding two pieces of metal into one solid pipeline by applying extreme heat. Any metal structure or tool that you might encounter on a jobsite likely has been formed using at least one weld somewhere.
Welding is an extremely efficient method of connecting two individual pieces of metal into a single piece, however there is a small possibility that a weld can fail, and that can spell big trouble for your business or employees. A weld failure can result in a rapid shift in equipment or materials which could cause massive injuries or death to any workers who may be nearby. Aside from the health and safety concerns, a weld failure can also halt your production and cost thousands of dollars in lost revenues or fines, especially if you are dealing with oil.
There are many reasons why a weld may be faulty or fail during operation. If your company utilizes inexperienced welders, or conducts welding in difficult conditions (outdoor welding in poor weather, long working hours for employees etc.) you may encounter weld failures more frequently than other businesses.
Common Methods of Failure
- Weld Joints are not heated to high enough temperatures. A welder cannot properly form one hot object to another cold object, both must be warm at the same time. Failure to do so can result in a weak weld.
- Failure to anneal could result in Annealing allows the materials to slowly cool down, opposed to rapidly cooling down a metal, which can cause the stress required to crack.
- Surrounding area affected by weld. Occasionally when welding, the operator can heat the materials or the area surrounding the weld joint. This can cause warping, which may result in improper alignment, putting large amounts of stress onto the weld which can lead to faults.
- Too much oxidation. When metals are heated, they can oxidize, which causes an improper weld to form. Welders can use a shield gas or flux to help prevent oxidation.
- Corrosion or chemical degradation. A welded area is more susceptible to rusting that a non-welded area and will begin to break down before the rest of the equipment or pipeline. Chemical exposure can also weaken a weld overtime.
- Bubble pockets or voids in welds. These are caused by moisture or CO2 forming from carbon and oxygen mixing. These bubbles can be hard to detect and can extremely weaken the strength of a weld.
- Unclean welding surfaces. Dirt and other debris can cause porosity in a weld which disrupts the uniformity of the structure and drastically decreases its overall strength.
Every company has different standards when it comes to quality. These quality standards and systems (QMS) need to be extended to all welding activities that are conducted by your business. Regardless of how intense your quality standards are, all welds must be inspected. A simple visual inspection is the first step, but when the safety of your employees is on the line and you are dealing with valuable resources/equipment, further measures must be taken.
20/20 NDT Inc. Tip -> Visual weld inspection must take place before, during and after the operator has conducted the welding.
Non-Destructive Weld Testing and Inspections
Due to the fact that a weld is a fusion of two metals, it can be very difficult to visually detect if there are any defects inside the weld. This is where non-destructive testing (NDT) valuable, giving you insight into the integrity of your welds, without damaging any equipment, while also allowing operations to continue smoothly.
Magnetic Particle Inspection
Electromagnetic particle inspection is one of the best non-destructive methods to detect surface cracks, defects that are too small for the human eye to see and discontinuities that are subsurface in a weld. This style of testing magnetizes the object in question, then utilizes a unique, fluorescent solution which highlights these defects for our inspector to document. This process is very fast and leaves your equipment unmarked.
Ultrasonic Inspection (UT) utilizes high frequency sound waves to examine the exterior and interior of solid objects. This style of testing is useful, not only for discovering cracks inside and out of a weld, but it can also measure exactly where the defects have been located. The equipment that we use at 20/20 NDT Inc sends high frequency beams into an object, and when it interacts with a defect, it will bounce back to our machine, giving us a clear picture of the potential defect and its exact location. This can be extremely useful if there is a small disruption in a large area of equipment. By pinpointing exactly where the crack or fault is, the issue can be quickly located and fixed, saving your company time while also leaving the other areas unaffected.
Radiographic inspection is one of the most universally accepted non-destructive testing methods that is extremely adaptable to a wide range of situations. This style of inspection utilizes “x-rays” or gamma rays to gain insight into the interior of machinery, or in this case, a weld. This is conducted in a similar manner to a doctor using an x-ray to examine if a bone is fractured or not. Again, set up is fast and simple, and our technicians can guarantee that your pipeline or equipment will be unharmed from this process.
If you are curious about the integrity of your welds, give our team at 20/20 NDT. Inc a call today! We service all of Western Canada and will bring the non-destructive testing to you. Let our technicians help you gain insight into the integrity of your operations and ensure the safety of your hardworking employees!