Hot bolting, or tightening bolts on flanges and other pipeline connectors while in operation, brings dangerous liabilities into fluid control operations. One example of the dangers occurred in 1992 where a hot bolted heat exchanger exploding killing 17 when a gasket-retaining ring slipped upon tightening. One common flaw in operators during maintenance practices is to believe they are more experienced and knowledgeable than is true, the Dunning-Kruger effect.
Bolts are only capable of shifting so far under stress, and during thermal loads the bolt materials may have reduced limits. Hot bolting adds stress to the material and combined with the lower limits these stresses may exceed resulting in ruptures or explosions of hot fluids. To reduce the risks of failure from thermal expansion springs may be added to bolted connections allowing more travel yet providing the needed sealing forces.
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