Page 113 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

PIPING

PIPING 2.63

FIGURE 2.33 Plug valve port sizes.

Ball valves are available in one-, two-, or three-piece body types (Fig. 2.34). The one-
piece body, also called “end entry,” is machined from solid bar stock material or is a one-
piece casting. The ball is inserted into one end for assembly, and a body insert that acts as
a seat ring is threaded in against the ball. The two-piece body, also an end-entry design, is
the same as a one-piece valve, except the body insert is larger and acts as an end bushing.
The three-piece body consists of a center body section containing the ball that fits between
two body end pieces. The entire assembly is held together by two or more body bolts. This
design allows the valve to be repaired without disassembling surrounding piping. This type
is recommended for utility services.
There are three port sizes, standard, reduced, and full port. Standard port is generally
one pipe size smaller than the valve size, reduced port is up to two sizes smaller, and full
port has the same opening as the connecting pipe.
Ball valves are generally selected for ON/OFF service. They are easily adapted to power
actuation and are generally less expensive than equivalent sizes of gate and globe valves.
With the development of high temperature and superior grade elastomeric seating material,
tight seating problems have been overcome.

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