Explain a standard torque sequence for a multi-bolt flange joint.

• A. Tighten bolts in a crisscross or star pattern, progressively to the final torque in multiple steps to equalize load.
• B. Tighten bolts in a spiral around the flange.
• C. Tighten all bolts in order of bolt number to final torque.
• D. Tighten only alternating bolts.

Answer: (A)

When torquing a multi-bolt flange, the goal is to apply clamping force evenly around the gasket to prevent leaks and avoid distortion. The standard approach is to tighten in a crisscross or star pattern, moving from one side to the opposite, and do so in several steps up to the final torque. This method distributes the load around the entire flange, so no single area is overcompressed early and the gasket seats smoothly.

If you were to tighten in a spiral around the flange or strictly in bolt-number order, you’d create uneven loading—one area would bear more load first, which can distort the flange and lead to leaks. Tightening only alternating bolts also concentrates stress and can tilt or unevenly seat the gasket.

Following the manufacturer’s torque specs, and using a multi-step, cross-pattern sequence, ensures a uniform clamping force and a reliable seal.