Minimum bolt preload must overcome which combination in a bolted joint?

Minimum bolt preload must overcome which combination in a bolted joint?

• A. External wind load and seismic load
• B. Internal pressure and gasket seating load
• C. Thermal expansion
• D. Vibration load

Answer: (B)

The bolt preload must provide a clamping force that keeps the joint faces together to resist internal forces that push the joint apart. The two forces that determine the minimum preload are the internal pressure acting on the gasket area (which tends to separate the joint) and the gasket seating load (the force needed to seat and compress the gasket to form the seal). Together, they set the baseline clamp required to maintain contact and seal under service. External winds or seismic loads, thermal expansion, and vibration can affect long-term performance or margins, but the essential combination for establishing minimum preload in a gasketed bolted joint is the pressure inside the vessel plus the gasket seating requirements.

The bolt preload must provide a clamping force that keeps the joint faces together to resist internal forces that push the joint apart. The two forces that determine the minimum preload are the internal pressure acting on the gasket area (which tends to separate the joint) and the gasket seating load (the force needed to seat and compress the gasket to form the seal). Together, they set the baseline clamp required to maintain contact and seal under service. External winds or seismic loads, thermal expansion, and vibration can affect long-term performance or margins, but the essential combination for establishing minimum preload in a gasketed bolted joint is the pressure inside the vessel plus the gasket seating requirements.