It is common in many industries for maintenance on bolted flange connections to be carried out only during periods of asset shutdown. The traditional reasoning for this is rational, as obviously, during normal production operations, no one wants to risk loss of containment.
However, some aspects of bolted flange connection maintenance can be dealt with during normal operations using a #hotbolting approach. Hot bolting is a method for changing out bolts on piping flanges whilst the process piping remains fully or partially pressurised. It is also known as single stud replacement, line bolting or bolt replacement.
The areas of bolted flange connection maintenance that can be covered by hot bolting before a shutdown are:
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Removal and replacement of corroded bolts
Removal and replacement of incorrect specification bolts
Reinstatement of required bolt tension via bolt replacement
Replacement of bolts on flanges that will be broken during shutdown to ensure efficient work scope execution
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These activities can be carried out before a shutdown to reduce work scope from the shutdown and increase the confidence that flanges will be broken promptly during the time-pressure environment of the shutdown.
With the number of flanges broken during some shutdowns, the opportunity to reduce this work scope type multiple times by removing it via hot bolting soon adds up to a significant shutdown work scope reduction overall.
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SRJ has helped dozens of companies reduce their flange maintenance workload before shutdown using the BoltEx® hot bolting flange clamp.
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BoltEx® hot bolting flange clamps are designed to act as a safety barrier that enables the safe exchange of the fasteners on bolted flanged connections whilst they remain pressurised.