Mud boxes are fitted into the machinery space bilge suction piping. The
mud box is a coarse strainer with a straight tailpipe down to the bilge
. To enable the internal perforated plate to be cleaned
when necessary, the lid of the mud box is easily removed without
disconnecting any pipework.
Suction pipes in tanks should be arranged with a bell mouth or foot.
The bell end or foot should provide an inlet area of about
one-and-a-half times the pipe area.
It should also be a sufficient distance
from the bottom plating and nearby structure to provide a free suction
area, again about one-and-a-half times the pipe area.
A steam trap does as its name implies and permits only the passage
of condensed steam. It operates automatically and is situated in steam
drain lines. Various designs are available utilising mechanical floats
which, when floating in condensate, will enable the condensate to
discharge . Other designs employ various types of
thermostat to operate the valve which discharges the condensate.
Fig:An Expansion bellows piece
An expansion piece is fitted in a pipeline which is subject to
considerable temperature variations. One type consists of a bellows
arrangement which will permit movement in several directions and
absorb vibration . The fitting must be selected according to
the variation in system temperatures and installed to permit the
expansion and contraction required in the system.
Drains are provided in pipelines and usually have small cocks to open
or close them. It is essential that certain pipelines are drained regularly,
particularly in steam systems. When steam is admitted to a pipeline
containing a reasonable surface of water it will condense and a partial
vacuum occur: the water will then be drawn along the pipe until it meets
a bend or a closed valve. The impact of the moving water in the
pipework will create large forces known as 'water hammer', which can
result in damage to pipework and fittings.
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