Valves cont'd

DOE-HDBK-1132-99

Consideration should also be given to provide future expansion of the system

without major system outages.

Particular attention to valve installation and positioning is recommended

to avoid head and knee injuries, eye injuries (due to the presence of valve

stems in the horizontal plane at eye level), and dripping hazards.

Valve access is best accomplished in the natural routing of pipe from

point to point, avoiding the use of vertical loops and pockets. Control

valves should be located adjacent to walkways wherever possible.

(Access platforms should be provided where valves are otherwise

inaccessible.)

Only infrequently operated valves should be located so that the bottom of

the handwheel is more than 6 feet, 6 inches above a floor or platform.

A minimum of 4 inches of knuckle clearance is recommended around

handwheels.

Chain-wheel operators can be used as long as they do not present a

hazard to operating personnel.

Control valves should be located near the operating equipment to be

observed while on local manual control.

Control valve manifolds should have a minimum of at least three

diameters of straight pipe both upstream and downstream of the control

valve.

Concentric reducers are recommended to make size reductions at the

control valve.

II-17