General piping requirements

As applicable, the following should be provided for all piping systems:

• All pumps, regardless of design service, should be nonoverloading during oper­
ation so the pump can operate at any point on its characteristic pump curve.

• Air vents should be installed on all high points in piping systems.

Air vent location is critical to air actually being vented versus just moving to the next lower air pressure area of the piping. Air and the odors associated with volatile compo­nents in the air accumulate in pipes when there is inadequate venting. Ultimately this air is then available to the building proper if there is an "escape route" from the piping. Common escape routes are dry floor drains, through toilet waters, across sink traps and into sink drain-head spaces, and any breaks in piping.

• Valves

—Vent and drain valves with hose-end connections should be provided on all mechanical systems.

—Drain valves should be installed at low points and for equipment that must be dismantled for routine servicing.

—Isolation valves, balancing valves, flow measuring devices, and pressure/ temperature test plugs should be provided at all heating and/or cooling ter­minal units.

—Bypass piping with isolation valves should be provided around all nonredun-dant control and system regulating valves.

• Pipe taps, suitable for use with either a 0.125 in. (3.2 mm) outside diameter (OD)
temperature or pressure probe, should be located at each pressure gauge.

• Coils

—All coils should be provided with valved drain and air vent connections.

—On air-handling units with multiple coils, isolation valves should be installed on the supply piping and a balancing valve on the return piping of each coil.

—A thermometer should be installed on the supply piping of each coil.

—Temperature/pressure taps should be provided on the supply and return pip­ing of each coil.

• Strainers should be provided with a valved blowdown connection and piped to
a floor drain.

• All underground metallic lines, fittings, and valves, except for cast iron soil and
storm drain piping systems, should be cathodically protected.

• All exterior, underground nonmetallic piping should be buried with pipe detec­
tion tape.

These design criteria ensure that system components can be located and isolated for maintenance. Areas where piping will be breached after isolation should be identified because in these areas exposure to workers and the environment from pipe contents is most likely during maintenance events. Identification of these areas should then be keyed to general building ventilation systems, location of PPE, and provisions for emergency exit­ing of the building proper.

Дата добавления: 2015-11-16