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As the new millennium dawned the intense new build programme of Combined Cycle Power Plants in the USA was underway to increase efficiency and reduce electricity production costs.It is common knowledge that ‘conventional coupling bolts’ suffer from seizure which results in damage to both the bolt and coupling bolt hole each time they are removed. All of which creates additional costs to that of bolt replacement.
Siemens Westinghouse decided to tackle this problem and specified PILGRIM’s Radial Fit Bolt for 43 new build 501F Gas Turbines with Pasadena 1&2 in Texas the first Power Plant to take delivery.
The principle of the PILGRIM’s Radial Fit Bolt is of a taper shank bolt drawn into a matching taper sleeve with parallel outer diameter which expands fractionally to produce a perfect interference condition in to the bolt hole. This condition, which “conventional” fitted bolts do not achieve, eliminates movement between mating components. Also with the expansion of the sleeve, exact flange alignment and concentricity is achieved. Axial clamp load is then created by a hydraulic puller. Once the puller draws the tapered bolt into its sleeve it is then used to tension the bolt once the nuts are fitted.
