Design basis

For Hot Bolting on old flange connections, the following design parameters are defined:

• Unknown remaining bolt tension after long time in operation
• Unknown conditions of the bolts
• Unknown conditions of the gasket
• Unknown how the gasket will act under increased or decreased load
• Failure of bolts could occur due to the increased stress resulting from adjacent bolt removal
• Unknown external loading
• Unknown how much force is needed to remove old rusted bolts
• Operation changes could occur and result in a different flow, temperature or pressure
• Unpredicted situations could occur, requiring all personnel to leave a Hot Bolting workplace

The Hot Bolting Clamp™ with work procedures is designed with respect to above parameters and good engineering practice. The design basis can be summarized as:

• Controlling the gasket stress to maintain a leak free gasket at maximum loading
• Prevent gasket crushing by including Backstops to counteract the tools pretension
• Impact tested low temperature materials to withstand low temperatures in case of any depressurization of the system
• Robustness to stand the forces needed for removing old rusty bolts with heavy equipment
• Robustness to stand the forces from pressure surges or pipe vibrating due to changes in the process system
• Robustness to achieve long term stability in cases where the Hot Bolting workplace must be abandoned for a long period
• Pressure tested to 1.5 X the design pressure on test flanges with all flange bolts removed
• ASME VIII design calculationFEM