U.S. Navy Piping Colors (c. 1970s)

(Created October 2017)

Designation

Type

Color

Description

MS

Main Steam

White

The main steam system carries steam at full boiler pressure and temperature from the generation unit to the propulsion turbines and the turbogenerators (and, if so equipped, to the boiler's soot blowers and some other auxiliary turbines). In addition, on aircraft carriers, main steam is used to supply the steam catapult system.

AS

Auxiliary Steam

White

This system supplies steam at various pressures and temperatures below full boiler pressure and temperature to places where it is needed for the operation of many systems and units of machinery, both inside and outside the engineering spaces, including hotel services, air ejectors, forced-draft blowers, and a wide variety of pumps.

AE

Auxiliary Exhaust

White

This steam system receives exhaust steam from the auxiliary turbines, which do not exhaust directly to a condenser. The pressure in the auxiliary exhaust system is maintained at about 15 psig. If the pressure becomes too high, automatic unloading valves (dump valves) allow the excess steam to go into the main or auxiliary condenser; in the event of failure of these unloading valves, relief valves will allow the steam to escape to the atmosphere. If the pressure in the auxiliary exhaust system drops too low, makeup steam is supplied from the auxiliary steam system through augmenting valves. The auxiliary exhaust system, which is not considered an auxiliary steam system, must be clearly distinguished from the various auxiliary steam systems.

GS

Gland-Sealing Steam

White

This is a low-pressure (0.5 to 2 psig) steam system used to supply steam to the shaft glands of the propulsion turbines and turbogenerators to seal them against air leakage into the turbine casings. On board most ships, gland-sealing steam is supplied from the auxiliary exhaust system, although in some ships it is supplied from the auxiliary or main steam systems. In either case the steam is supplied to the glands of the operating turbine via reducing valves or reducing stations.The high-pressure drain system collects the fresh water that condenses in the superheater headers, throttle valves, main and auxiliary steam lines, steam catapults (on carriers), and other steam equipment or systems that operate at pressures above 150 psig. These drains are then routed to the deaerating feed tank (DFT). The low-pressure drain system collects the fresh-water drains from those systems, machinery, or equipment that operate at steam pressures of less than 150 psig. These drains usually go directly to the fresh-water collecting tank.

HPD
LPD

High-Pressure Drains
Low-Pressure Drains

White

The high-pressure drain system collects the fresh water that condenses in the superheater headers, throttle valves, main and auxiliary steam lines, steam catapults (on carriers), and other steam equipment or systems that operate at pressures above 150 psig. These drains are then routed to the deaerating feed tank (DFT). The low-pressure drain system collects the fresh-water drains from those systems, machinery, or equipment that operate at steam pressures of less than 150 psig. These drains usually go directly to the fresh-water collecting tank.

LOS

Lubricating Oil

Yellow

This piping system is found on all ships. Its primary purpose is to provide lube oil to machinery, bearings, and other moving parts for lubrication and cooling.

LO

Lubricating Oil Purification

Black /
Stripes

Yellow
Stripes

This piping system is used to purify the lubricating oil from the main engine and the turbogenerators. The lube oil is purified by either the batch method or the continuous method.

FT

Fuel-Oil Filling and Transfer

Yellow

This system is used for receiving fuel oil to fill the fuel-oil storage tanks and then transferring it to fill the fuel-oil service tanks. This system can also discharge fuel in order to transfer it to other ships.

FS

Fuel-Oil Service

Yellow

This system, located in the engineering spaces, is used to provide "immediate use" fuel oil in the fuel-oil service tanks, to the ship's boilers, diesels or gas turbines.

JPS

JP-5

Purple

This system is normally found on aircraft carriers and other ships that carry some type of aircraft. It is used to provide aviation fuel to the aircraft. However, in case of emergency, this system can be connected to the fuel-oil system to allow JP-5 to be used as propulsion fuel.

AHP

High-Pressure Air

Dark Grey

This system is used to provide compressed air between 1000 psig and 5000 psig for charging scuba tanks, water deballasting, emergency starting of diesel engines, and torpedo ejection. If the compressed-air pressure required for a service is less than the system pressure, a reducing valve is employed.

AMP

Medium-Pressure Air

Tan

Medium-pressure compressed air is between 150 psig and 1000 psig. On most ships it is used to start emergency diesel generators, to control weapons and cargo elevators, and to activate the ship's whistle.

ALP

Low-Pressure Air

Tan

This system is often called the ship's service compressed-air system and provides compressed air at pressures of about 150 psig. Low-pressure compressed air is used throughout the ship to operate pneumatic tools and cleaning equipment and to perform a variety of other uses.

PW

Potable Water

Dark Blue

This system provides drinkable (potable) fresh water for all the ship's requirements, including sinks, scuttlebutts, showers, scullery, and galleys.

FW

Feedwater

Light Blue

This system originates at the output of the distilling plant. Fresh water produced by the distilling units can be directed to either the potable or feed-water system. The feedwater system provides makeup water in steam propulsion plants.

FM

Firemain

Dark Green

The firemain system distributes seawater throughout the ship under pressure for use in fire plugs (color-coded red), sprinkling systems, flushing systems, auxiliary machinery, cooling-water systems, and water wash-down systems.

CHT

Sanitary Flushing

Gold

The sanitary flushing system is supplied with seawater from the firemain, at a reduced pressure. The system provides seawater for flushing head urinals and water closets to move the waste either overboard or to ship's sewage collection and holding tanks.

WD

Plumbing

Gold

The drainage system aboard ship is divided into two parts: (1) the main and secondary system and (2) the plumbing and deck drain. Between them these systems collect and dispose overboard or to holding tanks all shipboard waste fluids.

VH

Hydraulic

Orange

Hydraulic systems are used on board ship to supply hydraulic oil to the steering gear, anchor windlass, elevators, remote control valves, and hydraulic presses.

CW

Chill Water

Blue

This freshwater system is used to provide cooling water for the electronic equipment's heat exchangers and air-conditioning heat exchangers in order to remove heat.