Although blades leave the factory in perfect condition, during transport, storage or installation, damages are bound to occur. Over the years, blades have gotten longer, which accentuates the problem challenging the transport industry of outfitting ships properly and building new trailers with better mounts, in addition to challenging those crane companies that handle the blades to handle them differently.
Because the weight of the blades has increased dramatically, when handling them, special care needs to be taken to ensure that point loading does not damage them. As we all know, blades are designed to operate in the air, with only the roots fixed, which does not occur until the blades are mounted.
The original equipment responsibility to have the blades installed in perfect condition is not only part of the contract for the new turbine, but also the manufacturer’s own protection against future warranty claims. Blade stands are designed to prevent damages, and diagrams are provided that designate lifting points.
Even so, the environment and other factors do not always cooperate, and damages occur. Although the original equipment manufacturer (OEM) is ultimately responsible for the condition of the blades, all repair costs attributed to mishandling or transport damages are covered by the damaging party or its insurance company. Therefore, in all cases, prevention of damages is the concern of all parties.
Although severe damages to blades have been known to happen, in most cases, the damages are scrapes or scratches that are merely cosmetic in nature. The repairs are much like what happens when you buy a new car: The dealer gets out the polish and removes the minor things that show on the paint job.
In other cases, the blade damage penetrates the skin of the blade, but again, this is not structural damage, and the repairs can be made without interfering with the integrity of the blade. More severe damages are rare and are handled on a case-by-case basis, with the OEM engineers determining the course of action.
In some cases, vortex generators (or other devices) that had been installed at the factory could be damaged. This, too, is an easy fix that does not affect the structure of the blade.
Wind farm developers can take several steps to ensure the blades are installed in perfect condition. This starts with the relationship between the developer and the OEM at the outset. Where will the blades be produced, and what are the logistics of getting them to the turbine? Asking these and other questions will help you gain an understanding of the risk of damage occurring.
For example, if the blades come from overseas, there is much more handling, with trucking to the port, loading the ship, unloading the ship in the U.S. and transporting to the site. Internally in the U.S., blades are transporting not only by truck, but also by rail (which, again, adds to the risk of damages).
In any case, questions should be asked regarding the details of each move. How is your asset being cared for, and what means have been put in place to prevent damages? Ships have been set up specifically for the transport of the blades. What ships are transporting your blades? At what port are they arriving? Is this a port that regularly receives and handles blades? Who is trucking the blades?
All of this information is good to know, and it is good for the OEM to know that you are interested. At each stage of transport and handling, the blades are inspected for damages. This is necessary to identify when the blades were damaged and who is responsible for the costs of the repairs.
In many cases, when the blades are offloaded and staged for shipment, these inspections take place, and repair crews are deployed to make repairs before they depart from the port. Again, when the blades arrive at the site or a storage yard, they are inspected, and repair crews have the chance to restore the blades again. Finally, once the rotor is assembled, the blades get the final inspection before beginning operations.
Although most blades do not require any attention during the logistics, some do. In all cases, the OEM and its engineering team have the responsibility of authorizing repairs and repair processes. They will also determine if a blade will be repaired or not in the case of more severe damage.
The OEM has a schedule to meet, and therefore, its first choice is to repair the blade. It does not have a financial interest other than that. So, the developer can rest assured that no blade will be repaired if there is any risk of the repairs being unsuccessful.
If the blade is scrapped, the insurance company of the damaging party will be responsible. However, many times, a replacement blade is not on-site, and there may be a delay in the receipt of that replacement.
Generally speaking, the developer is in the hands of the OEM. Just the same, as all repairs on blades are documented, request a history of each blade type. There should be documentation as to the manufacturing of the blade and the subsequent repairs or modifications to the blade. This information should be part of the commissioning process and continue through the warranty period, in which the OEM is responsible for the care of the blades, so that when that responsibility is turned over to the owner, historical data can be used to determine maintenance schedules. This information is also useful if a defect is found later. Was this something repaired in the past or a new occurrence?
In summary, the developer should get involved with the blades at the onset of the turbine supply contract. Working with the OEM will ensure that every precaution is being taken to get the blade installed without damages. In the cases in which damages have been identified, the developer should be involved with the damage report and determination of the decision to repair or replace. In all cases, if the developer does not have blade expertise, it can find an independent consultant to assist it.
Gary Kanaby is commercial manager for Houston-based service provider WindCom. He can be reached at (281) 227-5130 or email@example.com.