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Encyclopedia of Marine Technology


180 results

Preferential tripping

The use of automatic switches to trip or disconnect non-essential loads from the switchboard in the event of overload.


Preheat is used primarily to slow the cooling rate of a welded component in order to reduce the shrinkage stresses, prevent hardening and loss in ductility. It may be applied by propane gas torch.


The installation of both outfit and machinery items in large structural assembly units prior to these units being erected in the ship.


The intensity of force or force per unit area. A unit of pressure exists where a unit of force acts on a unit of area. A unit of pressure is the Pascal (Pa), i.e. Newton per square metre.

Pressure chambers

Pressure chambers are installed on board diving support vessels. Divers are accommodated inside, observed, medically checked and supplied.

Pressure charging

Increasing the density of the air charge usually accomplished on diesel engines by the use of exhaust gas turborcharging.

Pressure surge

A sudden increase in the pressure of the liquid in a pipeline brought about by an abrupt change in flow velocity. The pressure surge may cause a rupture of the piping and an extensive oil spill.

Pressure swing absorption (PSA)

The technology of inert gas production by the removal of oxygen from air used on LNG tankers.

Pressure-vacuum valve (P/V valve)

A valve which keeps the tank over pressure or under pressure within approved, limits. P/V valve provides for the flow of the small volumes of vapour, air or inert gas mixtures caused by thermal variations in a cargo tank.

Pressurised hold system

MacGREGOR’s patented ‘hold overpressure system’ is a way of maximising the weathertightness of hatch covers.


The mandatory wash of the cargo tanks prior to loading cargo.

Primary barrier of membrane containment system, primary membrane

The inner element designed to contain the cargo when the cargo containment system includes two barriers, (IGC CODE).

Primary bridge navigational equipment/systems

Equipment/systems essential for performance of primary bridge navigational functions: log, echo sounder, gyrocompass, radar, position-fixing system and electronic chart system.

Primary members of the hull structure

Floors and bottom girders, side stringers and web frames, deck transverses and deck girders, vertical webs and horizontal stringers on bulkheads. Primary members support secondary stiffeners.

Prime movers

All machines that convert primary energy to mechanical energy for use in propulsion or electric supply systems, e.g. the diesel engine, the gas turbine and the steam turbine plant.

Primer coat or ground coat (painting)

The first coat of the coating system applied in the shipyard after shop primer application.

Produced fluids

Fluids coming out of completed wells which may consist of oil, water, gas, and condensable vapour.


ANGELINA AMORETTI was built by Chinese shipyard Jiangsu Yangzijiang according to design from Kiel-based consultancy INEC GmbH.

Product tanker STENA PARIS

Claimed to be the safest and most efficient medium-range tanker, STENA PARIS is the first unit of a new series of P-MAX product tankers built by Brodosplit Shipyard.

Product tanker, product carrier

An oil tanker for carrying oil other than crude oil.

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