21st Century Fasteners Using Old Procedures
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Many standards organizations do not reflect the current mechanical safety and reliability needs of the modern wind turbine, according to Kerry Bock, a national sales engineer at Pittsburgh-based Heico Fasteners.
“In particular, standards may not be adequate for fasteners applicable to more demanding applications where cyclical loads, thermal cycling and other severe conditions are present,” Bock wrote in an article for nawindpower.com. “These conditions are often present in mechanisms such as wind turbine blade root bolts, gearboxes and drive mechanisms.”
“In particular, standards may not be adequate for fasteners applicable to more demanding applications where cyclical loads, thermal cycling and other severe conditions are present. These conditions are often present in mechanisms such as wind turbine blade root bolts, gearboxes and drive mechanisms. Many overseas turbine manufacturers rely on more updated European standards.
Overseas turbine manufacturers rely on more updated European standards. Organizations such as the DIN (German Institute for Standardization) appear to be leading in the progress toward more modern standards.
For example, DIN has recently withdrawn norms for several types of fasteners that have been deemed ineffective when used with modern high-strength bolts. Some of these fasteners include split lock washers, wave washers, external tooth washers, serrated lock washers, tab washers, lock nuts and crown nuts with cotter pins.
North American turbine manufacturers need to take a closer look into newer and more reliable fastener technologies that may not be reflected in current domestic standards.
Most fastener methods can be divided into several basic categories: friction based, adhesives, interference fit, compressive force based, safety wiring, adding more/longer bolts, and tension based.
For Bock’s full article click here.
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