Wind generation in the US experienced a rapid expansion between 2005 and 2007. Because these new sites required many miles of high voltage transmission infrastructure to deliver wind power to populated city centers, the manufacturers that designed and fabricated steel poles and lattice towers to the utility industry also needed to expand to serve this increased product demand. This expansion had a significant and very negative effect on the overall design and quality of new towers flooding the market. Meanwhile, several other trends converged with this explosion of wind to create a “perfect storm” of sorts for the power delivery industry. Those trends can be simplified to the following:
- The rapidly expanding tower fabrication footprint beginning in 2005 created training and staffing shortfalls that resulted in quality escapes (most notably welding defects) leaving the facility unbeknownst to construction and project engineering teams.
- Steel is not what it used to be! As more recycled material is utilized at US mills, steel becomes stronger, harder, but also more brittle. Brittle steel is extremely susceptible to cracking during cutting, forming, and welding. The difficulty of spotting these issues on turbines has also been matched by evolving technologies in drone and UAV inspection.
- Engineering designs have changed. Gone are the days of excessive safety factors. Overdesign makes for heavy, expensive structures which is why engineers are optimizing their towers to eliminate as much weight (and cost) from their products as possible. This is fine if you can produce a product perfectly 100% of the time during fabrication. Unfortunately, that is simply not possible. See trends 1 and 2!
Because of these three prominent factors, we have seen an alarming increase in defective welds and cracks in formed products appearing mostly in structures produced within the last 12-15 years. In fact, over the last several years Exo has inspected more than 40,000 transmission assets built by eight different fabricators, of which 61% were considered high-risk.
Now is the time for wind farms to take action against these risks, and one way to do so is by prioritizing weld inspections. This is an often overlooked area, as most wind farm operators are not aware of the systemic issues lurking in their structures, nor do they have the expertise to address such issues.
As you are exploring weld inspection options and approaches, consider the following tips and tricks.
The first thing you need to know is what to inspect on your wind farm. Weld inspections are most valuable on structural steel equipment in your substations, transmission lines, and even the structural towers for your turbine generators. Here’s what you should look for on each:
Balance of Plant:
Any wind farm utilizing galvanized tubular steel in their balance of plant (substation dead ends or transmission line) is at risk for catastrophic failure due to weld defects. Wind induced vibration from vortex shedding is also exacerbating the problem since transmission structures are not designed to account for fatigue cycles.
Although the design criteria and welding methods for turbine structural towers are a bit different than utility transmission towers, they are not immune to the trends listed above. In fact, there have been a number of manufacturing weld defects that have affected the industry over the last 10 years.
Unmanned aerial vehicle (UAV) technology is a powerful new tool to help owners visually inspect their system in a safe and cost-effective manner. Exo recommends the use of regular drone inspections as part of a preventative maintenance program in order to create baseline health records of your assets. Should the baseline indicate any kind of surface level weld defect or other structural issue, a more targeted, hands on NDT inspection can be performed as needed to fully assess the damage and potential risk on the system.
Wind farm inspections are a critical aspect of a lifecycle management approach to your assets. Rather than reacting to structural failures, do the work now to prevent them from occurring in the first place. By having welding inspected on your transmissions and turbines, you’ll be aware of potential issues and can appropriately monitor and remediate them before they become too costly.
At Exo, our Ex-Tend data-driven lifecycle management approach informs everything we do. When we conduct weld inspections, we provide the information you need to make strategic decisions that will prolong the lifespan of your assets. This can lead to significant cost savings, reduced risk, and improved business operations overall.
Are you ready you take the first step toward lifecycle management of your wind farm assets? Exo wants to help. Our team has experience working with wind farms like yours, and we can be brought in for one-time weld inspections, or we can lead a quality assurance program with a longer-term impact.
We’d love to hear more about your O&M challenges on the wind farm. Contact us today, and we’ll help you get started.