What are the best tools and techniques for checking flange alignment in piping systems?

1 Gap measurement

The gap between the flanges is the distance between the facing surfaces of the two flanges. The gap should be uniform and within the specified tolerance for the type and size of the flange. To measure the gap, you can use a feeler gauge, a taper gauge, or a digital gap gauge. A feeler gauge is a thin metal strip that can be inserted between the flanges to measure the gap. A taper gauge is a wedge-shaped tool that can be slid between the flanges to measure the gap at different points. A digital gap gauge is a device that uses a sensor and a display to measure and show the gap electronically. You should measure the gap at several points around the flange circumference and compare the readings with the specifications.

3 Angularity measurement

The angularity between the flanges is the degree to which the facing surfaces of the two flanges are perpendicular to the pipe axis. The angularity should be within the specified tolerance for the type and size of the flange. To measure the angularity, you can use a spirit level, a protractor, or a digital angle gauge. A spirit level is a tool that uses a bubble and a scale to measure the horizontal or vertical alignment of the flanges. A protractor is a tool that uses a semicircular scale and a pointer to measure the angle between the flanges. A digital angle gauge is a device that uses a sensor and a display to measure and show the angle electronically. You should measure the angle at several points around the flange circumference and compare the readings with the specifications.

4 Gap adjustment

If the gap between the flanges is not uniform or within the specified tolerance, you need to adjust it by tightening or loosening the bolts or nuts that hold the flanges together. To adjust the gap, you can use a torque wrench, a hydraulic tensioner, or a bolt stretcher. A torque wrench is a tool that applies a specific amount of force to turn the bolts or nuts. A hydraulic tensioner is a device that uses hydraulic pressure to stretch the bolts or nuts. A bolt stretcher is a device that uses mechanical force to elongate the bolts or nuts. You should follow the recommended tightening sequence and torque values for the type and size of the flange.

5 Parallelism adjustment

If the parallelism between the flanges is not within the specified tolerance, you need to adjust it by shimming or grinding the flanges. Shimming is the process of inserting thin metal plates between the flanges to compensate for unevenness or misalignment. Grinding is the process of removing material from the flange surface to make it smoother or flatter. To adjust the parallelism, you can use a shim kit, a grinder, or a flange facer. A shim kit is a set of pre-cut metal plates of different thicknesses that can be inserted between the flanges. A grinder is a tool that uses an abrasive wheel to cut or polish the flange surface. A flange facer is a device that uses a cutting tool to machine or resurface the flange surface. You should follow the recommended shimming or grinding procedures and check the parallelism after each adjustment.

6 Angularity adjustment

If the angularity between the flanges is not within the specified tolerance, you need to adjust it by bending or rotating the pipes or flanges. Bending is the process of applying force to change the shape or direction of the pipes or flanges. Rotating is the process of turning the pipes or flanges around their axis. To adjust the angularity, you can use a pipe bender, a pipe wrench, or a flange rotator. A pipe bender is a tool that uses hydraulic or mechanical force to bend the pipes or flanges. A pipe wrench is a tool that uses leverage to turn the pipes or flanges. A flange rotator is a device that uses electric or pneumatic power to rotate the flanges. You should follow the recommended bending or rotating procedures and check the angularity after each adjustment.