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Full text of "Modern Mechanical Engineering Vol-I"

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(Light Blue)

(Liyhl- Brown)

(Ye/tow )


In a coloured drawing, a key diagram of colour scheme should always be
given on the drawing itself. This saves waste of time and any possible

In making many of the arrangement drawings, care should be taken to
simplify them to the greatest possible extent. The necessity for this becomes
very evident in any piping arrangement, where pipes may cross one another
or be hung above others in a great multiplicity of arrangements, and which
it is extremely difficult to show clearly. It is usual to make one arrange-
ment drawing showing all the different systems of pipes, for the sake of
checking clearances in the drawing office, but such an arrangement is of
very little use in the shops, yards, ship, or to men on the site. It is therefore
necessary either to colour pipes by systems or, better still, to prepare separate

drawings for each system,
such as a steam and ex-
haust arrangement, an oil-
pipe arrangement, a lubri-
cating arrangement, a
hydraulic arrangement,
a sanitary arrangement,
bilge and ballast arrange-
ment, &c., as different
squads of men will be fit-
ting different systems in
all probability. In pass-
ing, it may be said the
old practice was to take

sets and make a great number of such pipes to place. This has largely
given place, particularly where pipes of large bore are concerned, to a
system of detailing these in the office, and only using closing lengths which
are made to place. This considerably adds to the drawing-office work,
but saves much time and delay in the shops, particularly as there is a
growing tendency to use steel and iron pipes where copper and lead were
once very common. The steel and iron pipes can be procured easily in
standard lengths, also bends and junction-pieces, at prices very much less
than they can be made for on site.

Where wrought iron or steel is used it is generally necessary to send out
block sketches of the material required, as it may come in " rough forged ".
Details are not shown on these sketches, but they give the outline and outside
dimensions with the usual extras for working and machining. When draw-
ings or order-sheets are sent out, a copy should on every occasion be filed
for drawing-office use. This filing should always be done by one person,
say the safe-attendant or drawing-office clerk, and each item should be
entered up in a register, giving date and characteristic number. Notes to
photographer, authorizing the taking of prints for the shops or for prices,
should be initialled by section leaders, and the recall of all drawings from
shops for alteration should be done by a note in the office duplication book.


Key to Colour Scheme