T.S. Patriot State Engineering Manual

Patriot State was the training ship of the Massachusetts Maritime Academy from 1986 to 1998.

Main and Auxiliary Circulating System

The main condenser, main lube oil cooler, and the Nash vacuum pump are supplied with cooling water by the main circulating system. When the ship is underway with sufficient speed, water may be circulated by a scoop injection; however, when the ship is maneuvering, operating at low speeds, or in port, the main circulating pump must be used.

The auxiliary circulating system supplies cooling water for the auxiliary condensers, the auxiliary lube oil coolers, and the air coolers.

A cross connection between the two circulating systems is provided for emergency operation, and the main circulating pump may to pump the engine room bilges in an emergency.

Main Condenser

Circulating water to the main condenser flows through a 36" line from the main injection scoop or through a 28" line from the main circulating pump. A motor operated gate valve fitted with two hose connections for valve seat flushing is provided in each inlet line. A check valve in each line prevents recirculation between the main scoop injection and the main circulating pump injection.

The main condenser water heads are fitted with 2" vent lines which are combined and led to the main condenser 10" overboard discharge. A relief valve, set at 20 psi, is installed on the main condenser circulating water overboard discharge 36" line to protect the system and water side of the condenser from excessive pressure.

Circulating water is discharged overboard from the main condenser by either a 36" line through the bottom shell of the ship or a 10" overboard discharge sea chest at the 19" water line. Each discharge line is fitted with a motor operated gate valve. The gate valve in the 36" line is fitted with two hose valves for valve seat flushing.

An emergency source of circulating water is provided by the auxiliary circulating water pumps through a 10" connection on the inlet water head of the main condenser. A 20" main bilge injection controlled by a stop-check angle valve is connected to the suction piping so that the main circulating pump may be used as emergency bilge pump.

The main injection scoop, the main circulating pump suction sea chest, and the main condenser discharge sea chest are each fitted with a rubber expansion joint adjacent to the check valve.

Auxiliary Condensers

The auxiliary condensers and the associated turbo-generator coolers are supplied cooling water single-stage centrifugal pumps, each having a capacity of 1460 gpm and a total head of 25 feet. Auxiliary circulating pump suctions are via individual 10" branch lines which take suction through 14" lines from either a higher or low sea chest. The discharge from the auxiliary circulating pumps is cross-connected so that any pump or combination of pumps may supply the auxiliary condensers and turbo-generator coolers, or the 10" emergency line to the main condenser. A relief valve, set at 20 psi is installed in the discharge piping of the auxiliary circulating pumps to protect the auxiliary condenser circulating system from excessive pressure. The head of each auxiliary condenser is fitted with a 1/2" valved drain to bilge connection. The turbo-generator cooler and auxiliary condenser discharges combine and discharge overboard through a common 12" line and overboard sea chest at the 19" water line. The turbo-generator air coolers are vented by a 1/2" vent valve provided at the top of the air cooler for the removal of any entrained air. Telltale or leakage vents for each air cooler provides a visual indication of a leaky inner tube or a loose joint between the inner and outer tube sheet. These vents should never be closed.

Lube Oil Coolers

Parallel 8" lines from the inlet head of the main condenser supply each main lube oil cooler and discharge overboard via a common line through an overboard sea chest. A 4" branch lines supplies the Nash vacuum pump.

The outlet head of each lube oil cooler is fitted with a 1/2 valved drain connection to empty the cooler by gravity to the bilge. A 3/4" hose connection is located on each lube oil cooler inlet head for supplying auxiliary exhaust steam for heating lube oil when necessary.

Circulating Pumps

The main circulating pump is a two speed vertical motor driven single stage pump with a 8,500/20,700 gpm capacity with a total head of 15/38 feet, powered by a 150 HP motor. The unit runs at 700 rpm.

The three auxiliary circulating pumps, are vertical motor-driven, single stage, centrifugal pumps with a 1460 gpm capacity running off a General Electric 15 HP, 440 volt, 60 cycle motor. The units run at 1150 rpm.

Circulating System Operation

When switching to or from scoop operation, be sure to check for proper operation of the check valves by noting the position of the external torque arms. Be aware that starting the main circulating pump causes a significant load on the turbogenerators.

The vent lines in the condenser heads should be open during operation to permit positive venting of the condenser. If air is allowed to collect in the upper part of water chest, cooling water will be cut off to the tubes in that area, causing overheating and expansion of the dry tubes, and resulting in leakage of the tube sheets.

The flow of cooling water to the main and turbogenerator lube oil coolers should be regulated by the outlet valve to maintain a constant lube oil temperature of 110° F.

Direct comments to William Haynes whaynes@maritime.edu
Mon, Jul 1, 1996
TSPS Engineering Manual ©1995 Massachusetts Maritime Academy