𝐇𝐨𝐭 𝐁𝐨𝐥𝐭𝐢𝐧𝐠:
The sequential removal and replacement of bolts on flanged joints while the unit is under reduced operating pressure. The procedure generally consists of removing one bolt at a time in a flange, re-lubricating it, reinstalling it (or a new bolt), and retightening it to a specified torque. Hot bolting can be performed while the unit is online or once the unit is depressurized. If performed while the unit is online, consideration of the risk of leakage includes the number of bolts in the flange and the hazard associated with the contained process fluid. Hot bolting is used either to replace corroded or defective bolts or to proactively increase the gasket stress to prevent leakage (in high-temperature or cyclic services) or to reseal a small stable leak.
𝑵𝑶𝑻𝑬: Hot bolting while the unit is online to increase gasket stress or seal a small stable leak is not recommended or required if turn-of-nut tightening can be used. An engineering and risk analysis of the hot-bolting operation should be carried out to establish that the operation can be performed safely. 𝑹𝒆𝒇𝒆𝒓 𝒕𝒐 𝑨𝑺𝑴𝑬 𝑷𝑪𝑪-2 for further information on joint-tightening activities once the unit is fully operational.
Ref.: ASME PCC-1
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