What is bolt up pattern on pipe flanges?

The bolt-up pattern on pipe flanges refers to the specific arrangement and sequence in which bolts are tightened to secure the flanges together. This pattern is typically designed to ensure even distribution of stress and to prevent misalignment or warping of the flanges. Commonly, a star or crisscross pattern is used, starting from the center and moving outward, to achieve uniform compression of the gasket. Proper bolt-up procedures are crucial for maintaining a leak-proof seal in piping systems.