i) Gray cast iron valves are not to be used as shell valves. Nodular iron valves are acceptable, see 4-6-2/3.1.4.
ii) Shell valves are to be installed such that the inboard piping can be removed and the valve can remain in place without impairing the watertight integrity. Wafer-type butterfly valves are not acceptable. Butterfly valves with lugs, however, may be accepted.
iii) Controls for positive closing valves are to be readily accessible and controllable from the floors or gratings. Open or closed indicators are to be provided, see 4-6-2/5.11.3(a).
iv) Power-operated valves are to be arranged for manual operation in the event of a failure of the power supply.
v) For hydrostatic tests, see 4-6-2/7.3.2.