When butterfly valves are to be installed between welding type flanges, care should be taken to ensure no damage will occur to the seat:

1 Place the valve between the flanges with the flanges and valve body aligned. The disc should be 10% open.

2 Bolt the flanges to the valve body. Ensure the valve and flanges are aligned with the pipe.

3.Tack-weld the flanges to the pipe.

4 Remove the bolts and the valve from the pipe flanges and finish welding the flanges.

5 Wait for the pipe and flanges to cool before installing the valve. NOTE: Never complete the welding (after tacking) with the valve between flanges as heat transfer will cause severe seat damage.

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