Repairing holes and replacing bolts connecting rotating flanges on a shaft is a task that poses ship operators potential issues. Indeed, this maintenance process can lead to unpredictable and lengthy periods in dry docks—not ideal when there are deadlines to meet. There are many factors that contribute to making refitting these components a challenge.
Installation leads to downtime
Conventional fitted bolts have to be “mauled” into place with a sledgehammer—requiring time-consuming honing of the holes and individual grinding of the bolts. This design is not as efficient and cost-effective as it could be. Significant force is required to install and remove these bolts. When a sledgehammer does not offer enough power to knock them in or out of place, destroying the bolts by boring them out may be the only option. All of which will potentially scratch or damage critical shaft flanges and couplings on a ship.
And it is not just the force required that makes this procedure difficult. A variety of mounting equipment may be needed for installation and removal. Repeatedly carrying out this process increases the likelihood of seizure of the bolts, misaligned shafts, or slippage—something that can result in even more serious problems and failures of the propeller line. As a result, ship operators can experience unexpected downtime, and difficulties with the bolts make it hard to predict how long the repair will take. However, these issues can be dealt with.
An efficient solution for smoother performance
Tailor made hydraulic bolts are an upgrade to existing products on the market, simplifying and speeding up the installation process. The hydraulic puller, or tensioner, will both expand and preload the expandable sleeve in a single operation, therefore requiring fewer tools. This makes the process more manageable and safer for operators, ultimately meaning that more time is spent at sea rather than on maintenance.
And, as with the established Supergrip Bolts from SKF, no new bolts are needed when the flange connection has to be removed and reinstalled again. All bolts are fully reusable for as long as it is required. By being able to set expansion and axial preload to predetermined levels, ship operators can ensure coupling slippage is no longer an issue as a result of the powerful interference fit.
Designed with operators in mind
Quickgrip Bolts from SKF are designed to tackle these problems. They reliably protect against issues such as fretting, coupling slippage, potential vessel damage, and extended downtime. These bolts will be showcased at Nor-Shipping 2017 and are already available for purchase. With the product, ship operators can rest assured that their vessels are being kept in good condition and unpredictable ship downtime is reduced.