and
over should have valve bodies, caps and yokes of steel castings.
Spindles should be of some non-corrosive metal, such as "monel metal".
Seat rings should be removable of the same non-corrosive metal as should
the spindle seats and plug faces.

All salt water valves should have bronze spindles, sleeves and packing
seats.

The suggestions as to flanges for different classes of service made on
page 311 hold as well for valve flanges, except that such flanges are
not scored.

Automatic stop and check valves are coming into general use with boilers
and such use is compulsory under the boiler regulations of certain
communities. Where used, they should be preferably placed directly on
the boiler nozzle. Where two or more boilers are on one line, in
addition to the valve at the boiler, whether this be an automatic valve
or a gate valve, there should be an additional gate valve on each boiler
branch at the main steam header.

Relief valves should be furnished at the discharge side of each feed
pump and on the discharge side of each feed heater of the closed type.

Feed Lines--Feed lines should in all instances be made of extra strong
pipe due to the corrosive action of hot feed water. While it has been
suggested above that cast-iron threaded flanges should be used in such
lines, due to the sudden expansion of such pipe in certain instances
cast-iron threaded flanges crack before they become thoroughly heated
and expand, and for this reason cast-steel threaded flanges will give
more satisfactory results. In some instances, wrought-steel and Van
Stone joints have been used in feed lines and this undoubtedly is better
practice than the use of cast-steel threaded work, though the additional
cost is not warranted in all stations.

Feed valves should always be of the globe pattern. A gate valve cannot
be closely regulated and often clatters owing to the pulsations of the
feed pump.

Gaskets--For steam and water lines where the pressure does not exceed
160 pounds, wire insertion rubber gaskets 1/16 inch thick will be found
to give good service. For low pressure lines, canvas insertion black
rubber gaskets are ordinarily used. For oil lines special gaskets are
necessary.

For pressure above 160 pounds carrying superheated steam, corrugated
steel gaskets extending the full available diameter inside of the bolt
holes give good satisfaction. For high pressure water lines wire
inserted rubber gaskets are used, and for low pr