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6.2 Valve configurations

6.2.1 Full-opening valves
Full-opening flanged-end valves shall be unobstructed in the fully opened position and shall have an internal bore as specified in Table 1. There is no restriction on the upper limit of valve bore sizes. Full-opening through-conduit valves shall have a circular bore in the obturator that allows a sphere to pass with a nominal size not less than that specified in Table 1.
Welding-end valves can require a smaller bore at the welding end to mate with the pipe. Valves with a non-circular opening through the obturator shall not be considered full opening.

6.2.2 Reduced-opening valves
Reduced-opening valves with a circular opening through the obturator shall be supplied with a minimum bore as follows, unless otherwise specified: valves ON 300 (NPS 12) and below: one size below nominal size of valve with bore according to Table 1; valves ON 350 (NPS 14) to ON 600 (NPS 24): two sizes below nominal size of valve with bore according to Table 1; valves above ON 600 (NPS 24): by agreement. EXAMPLE A DN 400 (NPS 16) - PN 250 (class 1500) reduced-opening ball valve has a minimum bore of 287 mm. Reduced-opening valves with a non-circular opening through the obturator shall be supplied with a minimum opening by agreement.
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