Page 312 - Ship Construction.DJ Eyres 6Ed

Ch26-H8070.fm Page 301 Wednesday, October 18, 2006 7:01 AM
Pumping and Piping Arrangements 301
for each pipe in a chest on the forward side of the bulkhead. An indicator is
provided to show at the valve operating position whether it is open or closed.
Bilge mains in passenger ships are kept within 20 per cent of the ship’s
beam of the side shell, and any piping outside this region or in a duct keel is
fitted with a non-return valve. These requirements are intended to prevent
any compartment from becoming flooded when the ship is grounded or
otherwise damaged and a bilge pipe is severed. Many passenger ships are
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provided with divided deep tanks or side tanks which permit cross flood-
ing arrangements limiting the list after a casualty. This cross flooding is
generally controlled by valves operated from above the bulkhead deck, but
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self-acting arrangements can also be adopted.
Bilge and ballast piping may be of cast or wrought iron, steel, copper, or
other approved materials. Lead or other heat sensitive materials are not
permitted. The piping is fitted in lengths which are adequately supported
and have flanged connections, provision being made for expansion in each
range of pipes.

SCUPPERS Scuppers are fitted at the ship’s side to drain the decks.
Figure 26.1 shows a scupper fitted above the freeboard deck. Below the
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freeboard deck and within the intact superstructures and houses on the
freeboard deck fitted with weathertight doors, these scuppers may be led to
the bilges. Alternatively they may be led overboard provided that –

(a) the freeboard is such that the deck edge is not immersed when the
ship heels to 5 degrees; and
(b) the scuppers are fitted with means of preventing water from passing
inboard (usually a screw down non-return valve capable of being
operated from above the freeboard deck).

General Service Pipes and Pumping
Pumps and substantial piping systems are provided in ships to supply the
essential services of hot and cold fresh water for personal use, and salt water
for sanitary and fire fighting purposes.
Many large passenger ships are provided with a large low-pressure dis-
tilling plant for producing fresh water during the voyage, as the capacities
required would otherwise need considerable tank space. This space is better
utilized to carry oil fuel, improving the ship’s range. Independent tanks
supplying the fresh water required for drinking and culinary purposes, and
fresh washing water, etc., may be taken from the double bottom tanks, the
pumps for each supply being independent also. Hot fresh water is supplied
initially from the cold fresh water system, through a non-return valve into a