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904. Sectional model of Yarrow boiler. (Scale 1 : 10.) Made
in the Museum from drawings supplied by Messrs. Yarrow
& Co., 1903. Plate XL, No. 4. N. 2348.

This water-tube boiler is a development of the type of " small-tube f ' or
" express " boiler patented by Mr. A. F. Yarrow in 1889 and which he so
extensively employed in torpedo boats. As the advantages of the water- tube
system of construction became more generally realised, the advisability of
using in cruisers and battleships similar boilers, but adapted for continuous
steaming, led to the introduction of the " large-tube " modification shown
by the model. The boiler represented is one of 24 fitted in 1903 on two
Chilian battleships, now H.M. ships "Swiftsure" and "Triumph," there
being 12 boilers in each vessel, arranged in four groups of three ; the model
shows the centre one of a group together with a portion of its uptake.


The boiler itself consists of an upper horizontal cylindrical vessel, or
steam drum, and two lower ones, or water barrels, connected by inclined
straight tubes expanded at their ends into holes in the shells which are
thickened where serving as tube plates. The water barrels are of flattened
section, owing to their tube plate portions being made of the same curvature
-as the steam drum, while their diameter is less. Each of these cylindrical
vessels has a manhole at the front end, and the upper vessel is provided with
the usual mountings and valves, including an internal steam collecting pipe.
There are 1,008 tubes 1 75 in. external diameter to each boiler, all delivering
into the steam drum below the water level, and those in the rows nearest
the fire are of extra thickness ; the tubes as well as the shells are of steel,
the use of brass tubes having been discontinued by Mr. Yarrow since 1894.
To accurately maintain the spacing and to give rigidity to the mass of tubes,
strips of plate provided with semicircular notches and known as " dodge
grips " are inserted diagonally between the rows of tubes at the middle of
their length. There are no external downcomers or water return tubes
provided in this boiler, these having been dispensed with after trials on a
torpedo boat had shown that the outer rows of tubes adequately served this
purpose, while acting also as heating surface.

The whole area between the two water barrels is occupied by the grate,
the sides of which are formed of firebrick supported by ribbed cast-iron
backing ; the ends of the furnace are also of firebrick, which is, however,
supported by a double casing of sheet steel packed with asbestos to reduce
the radiation losses. The flame and gases from the furnace, after passing
between the tubes and thereby giving up most of their heat, enter the outer
casing, by which they are led to the uptake and funnel ; this casing fits over
the steam drum and has its outer surfaces built of three thicknesses of sheet
steel, the space between the two inner ones forming an air jacket while the
outer space is packed with asbestos. Suitable doors are provided in the
front and side of the casing to give access to the interior and to the tubes for
inspection or repairs. Uniform distribution of the gases around the tubes
is facilitated by two horizontal baffle plates which contract the central
portion of the opening into the uptake ; there are also two baffles restricting
the flow of gases at the upper ends of the outer tubes.

The boiler is carried upon feet which are secured to bearers constructed
as web frames and attached to the inner skin of the ship. The ashpans and
grate are supported by three main girders, carried by plate frames arranged
beneath the front and back of the boiler and extending upwards from the
inner skin; these girders are further supported by three intermediate
A frames. The firebar bearers directly rest iipon cast steel girders supported
t>y short columns from the main girders beneath them.

The boiler represented has 3,127 sq. ft. of heating surface, and 55 -3 sq.
ft. of grate area ; the working pressure is 280 Ib. per sq. in., and the steam
it supplies is equivalent to 1,000 indicated h.p.

905. Drawings of Babcock and Wilcox water- tube boiler.
(Scales 1 : 8 and 1 : 12.) Presented by Messrs. Babcock
and Wilcox, Ltd., 1904. N. 2359.

These drawings represent the marine type of Babcock and Wilcox boiler
^hich, in essential features, differs very slightly from the land boiler (see
Mechanical Engineering Collection).

The original form of this boiler was introduced into the American Navy
in 1889, and in 1893 was fitted in the S.S. " Tasso " by Messrs. T. Wilson,.
Sons & Co., of Hull. Extensive trials made with in 1897-98 in H.M.S.
4t Sheldrake " proved so satisfactory, that it is now one of the few standard
types of water-tube boiler used in H.M. ships. The pressure parts of the
boiler are constructed wholly of wrought steel, and consist of an arrangement
of inclined tubes forming the heating surface attached to vertical sinuous
boxes or headers. Connected with the upper ends of the front headers by
short tubes is the steam drum, whilst horizontal tubes connect the drum
with the rear headers. The bottoms of the front headers are connected by


nipples with a square forged steel sediment box, through which the boiler
can be completely drained. The furnace extends to nearly the full width of
the boiler, and is built of ordinary firebrick or of light fire tiles bolted to the
side plates.

The inclined tubes are divided into vertical sections placed at 15 deg. to
the horizontal. These tubes are of seamless steel ; opposite each of them in
the header is a handhole for cleaning purposes.

There is a continuous circulation in this boiler, cold water coming down
the front headers from the bottom of the steam and water drum, whilst
steam and hot water flow up the tubes and rear headers and to the steam
drum by means of the horizontal return tubes at the top. Baffle plates are
placed in the steam drum, against which the steam and water are directed,
thus causing the water to be thrown down whilst the steam passes round
the ends of the baffles to the perforated pipe connected with the stop valve.
Wash plates are fitted within the steam drum to prevent undue movement
of the water when the ship is rolling.

The whole of the pressure parts are encased in a double sheet steel
casing with asbestos between; an outer corrugated plate provides an air
screen. Removable doors, are constructed in both side and end casings to
give access to the tubes.

The chief difference between this boiler and the land type is the position
of the steam drum, which is, in this case, in front of the boiler and across
the tubes, instead of running from front to back as in the land type. The
tubes must, therefore, be inclined downward from back to front, in order
that the valves and fittings on the steam drum may be at the stoking end
of the platform.

The left-hand drawing represents a boiler suitable for battleships,
with tubes 3 25 in. diam., whilst the other drawing shows a boiler, designed
for either battleships or cruisers, which has two rows of tubes 4 in. diam.
at the bottom, the remainder being 1 37 in. diam.

Some data concerning the boilers appear on the drawings.

906. Sectional model of Reed boiler. (Scale 1 : 10.) Made
in the Museum from drawings supplied by Palmers 'Ship-
building and Iron Co., Ltd., 1905. N. 2387.

The water-tube boiler represented is of the small-tube " express " type,
and was patented in 1893 by Mr. J. W. Reed. It has been largely used in
the British Navy for torpedo boats and destroyers.

There are three horizontal vessels ; the upper cylindrical one is the steam
drum and the two lower ones of flattened section are the water barrels.
Provision for the return of water from the steam drum to the water barrels
is made by four downcomers. The water barrels are connected with the
steam drum by 1,774 generating tubes, 1-0625 in. diam., except the two
rows on each side neUrest the fire which are 1 3125 in. diam. There are no
water- walls.

The special feature of this boiler is the tube joint. On each end of the
tube, a hemispherical washer or nut is fastened which fits into a corre-
sponding recess in the tube plate. When the nuts on the tube on the inner
side of the tube plate are screwed up, the spherical surfaces fit closely, the
joint thus accommodating itself to any slight deviation of the tube from
the correct line. An accompanying sketch shows the joint on a larger

A manhole door for access to the steam drum is provided at the front
end, whilst the water barrels have a number of handhole doors along their
flattened sides. There are the usual mountings on the steam drum ; an
internal steam collecting pipe is dispensed with, however, by taking the
steam from a steam dome. The grate comprises the whole area between the
two water barrels, its sides, front and back being formed of fire-brick.

To guard against radiation losses the casing enclosing the boiler is made
of two sheets of steel with a 2 in. air space between, the whole being made
rigid by channel bars, perforated by 1 in. holes to provide for a continuous


circulation of air, between the casings. A lining of 5 in. asbestos covers
the inner casing. To ensure the gases traversing the whole of the tubes
before escaping to the uptake, asbestos baffles are provided, resting on the
backs of the outer tubes. Doors are provided in the front casing to give
access to the tubes for cleaning purposes and for repairs, whilst the side
casing consists of large portable doors, by means of which repairs are easily
executed. The boiler is shown with a portion of the uptake, the latter
being of the same construction as the boiler casing. Baffles, consisting of
three sheets of steel forming a hollow triangular prism, are placed in the
uptake to direct the flow of the gases. The boiler is carried on two cradles
placed under the water barrels, each consisting of a plate girder (forming
also the furnace side) with gusset plates at either end. The weight is thence
transmitted to the floor plates and obiter skin of the ship by means of deep
longitudinal frames. The grate is supported independently by bearers on
vertical columns attached to the centre and side keelsons of the vessel. The
boiler represented has 79 '75 square ft. of grate area, and 3,878 '5 sq. ft. of
heating surface ; the working pressure is 250 Ib. per sq. in.

907. Sectional model of Niclausse boiler. (Scale 1 : 10.) Made
in the Museum from drawings supplied by Messrs. Hum-
phrys, Tennant & Co., 1904. Plate XI., No. 5. N. 2362.

This is a form of water-tube boiler in which slightly inclined tubes
closed at one end have within them circulating tubes opening into separate
portions of vertical water chambers or headers; each double tube acting
similarly to the well-known Field tubes. This arrangement was patented in
1878 by M. Collet, but its practical success is due to the work of M. M.
Niclausse, who patented, between 1891 and 1900, an improved form of tube
joint for this purpose.

The model represents one of 18 boilers fitted in 1904 on H.M.S. " New
Zealand," being four-fifths of the total boiler power. It shows, partly in
section, one of a group of six boilers, together with part of the uptake.

The boiler contains 16 elements, each consisting of a malleable cast-iron
header with 20 steel tubes inclined at 6 deg. to the horizontal, arranged
zig-zag in two vertical rows. The headers are each divided by an internal
partition into two chambers, one behind the other, and they are all connected
at the top, by means of bolts and double-coned nipples, to a collecting drum.

The outer tubes communicate with the back chambers of the headers,
while the inner tubes open into the front chambers, so that the water from
the drum may pass down the headers and through the inner tubes to the
end of the larger ones, and then, together with the steam generated, return
through the space between the two tubes and up the headers again into the
drum, without the two streams mixing or interfering. The water level is
3'5 in. below the centre of the drum, and over each header is fitted a cap
which separates the hotter from the cooler water.

The headers are connected at the bottom with blowing-out pipes, but
this form of boiler cannot be completely emptied without removing the
tubes. The outer tubes pass through the headers and are fitted with cone
joints at the front and back intersections ; the tubes themselves are enlarged
to form the rear cones and to fill the orifices in the partitions, while steel
collars screwed on the ends provide the front cones. Portions of the tubes
are cut away on both sides of the partition to form passages for the water.
Each inner tube is riveted to a skeleton extension piece screwed to a cap,
which is itself screwed into the outer cone ring, while passage of the water
from the front chamber to the outer tube is presented by a surrounding
ring ; the back end of the tube is supported by a winged collar. Dogs
outside the headers keep the conical surfaces in contact, little retaining
pressure, however, being required owing to the areas being nearly equal ; an
adjacent drawing shows this joint in detail. The outer tubes are 3 3 in.
external diam. and 7 '36 ft. long, the four lower rows being '236 in. thick,
and the remainder 16 in. thick ; the inner tubes are 1 56 in. diam. and
036 in. thick. The back ends of the tubes are closed by screwed caps, and


are supported in holes in cast-iron plates ; small spaces are left between the
headers to allow the tubes to be cleaned outside by a steam jet.

The headers and tubes are supported on shelves at front and back, and
are surrounded by a casing built of flanged steel plates. The side walls
above the furnace are of two plates, with non-conducting material between,
and on the outside walls a third sheet forms an air casing. The uptake rises
behind the drum, and is built up of three sheets stayed together and
stiffened by angles ; the inner space forms an air casing, and the outer is
packed with lagging material. There are three furnace doors ; the whole
area below the tubes is occupied by the grate, which slopes at the same
angle, and is carried by transverse bearers supported on the walls ; the sides
of the furnace are formed of firebrick. The flame and hot gases from the
furnace, after passing between the tubes, enter directly into the uptake and
chimney ; their passage is retarded by baffles formed of pipes resting on the
tubes. The front of the boiler above the furnace is closed by shutters secured
by H-bars and cotters. Air for combustion is supplied through the ash-pan
doors, some of it passing through the grate, and some entering above it
through passages in the back brickwork ; air jets also enter from a pipe
above the fire doors. The boiler is carried on plate girder bearers attached
to the inner skin of the ship, and the ash-pans rest on these.

The boiler has 1,992 sq. ft. of heating surface and a grate area of
63 5 sq. ft. ; the working pressure is 220 Ib. per sq. in. ; it supplies about
15,000 Ib. of steam per hour, equivalent to about 850 h.p.

908. Sectional model of Thornycroft-Sclmlz boiler. (Scale
1 : 10.) Made in the Museum from drawings lent by Messrs.
John I. Thornycroft & Co., 1904. Plate XI., No. 6. N. 2352.

The original form of this water-tube boiler was patented by Sir John I.
Thornycroft in 1885, and first fitted on H.M. torpedo boat " Speedy " (see
No. 902). It was subsequently extensively used in other vessels of the class,.
but when, in 1890, the larger vessels known as torpedo-boat destroyers were
being introduced, a type of " express " boiler was required with increased
heating and grate surface ; this more powerful development was first adopted
011 H.M. destroyer " Daring," and afterwards on many other destroyers.
The boiler represented in the model is, however, a modification of the
'* Daring " type in that, by an arrangement of tubes patented in 1894 by
HeiT R. Schulz, a somewhat different course is given to the gases ; it is,
therefore, known as a Thorny croft- Schulz boiler.

The boiler has four horizontal cylindrical vessels, the three lower ones
being water barrels, while the upper and larger one is a steam drum. The
steam drum is connected to the central water barrel by eight curved
downcomers, while one large external tube forms the downcomer by which
the water passes from the steam drum to each of the other barrels. Manhole
doors are provided at each end of the barrels and at the front end of the
drum, and the latter carries the usual mountings and an internal collecting
pipe ; there is also within it an automatic feed-water regulator, controlled by
a long cylindrical float, and having an external adjustment by which the
water level can be varied.

The generating tubes connecting the water barrels to the steam drum
are 1,764 in number and mostly 1*125 in. diam., those exposed to the
furnaces being, however, 1*375 in. diam. The tubes form the sides and
crowns of the two furnaces, and, to prescribe a definite path for the flame
and gases around them, the rows adjacent to the furnaces, as well as the-
external rows, are formed into " water walls " by the tubes in two rows
being brought together so as to form a complete wall, except at the ends,
where they are necessarily splayed to enter the tube plates. In this way the
gases are caused to travel along nearly the whole length of the tubes before
escaping to the uptake, while owing to the shape of the tubes the steam
drum is protected from the direct action of the flames.

The boiler is completely enclosed in a casing made of a sheet of steel,
with an asbestos lining fitting closely on to the outer water walls ; in the
u 6773. TT


region above the furnaces an air casing is provided. The furnaces are lined
with fire-brick, and the water barrels are protected from the direct action of
the fuel by the same material.

In the earlier forms of this boiler, the tubes were " undrowned," i.e.,
they all opened into the steam drum above the level of the water in it ; in
some of the later examples, however, a considerable proportion of the tubes
enter the steam drum below the water level, or are " drowned." The boiler
is shown with a portion of its uptake, the latter being constructed of thin
sheet steel with sheet asbestos on the outside, and secured by 2 -in. strips of
steel placed over the joints.

The boiler represented has 4,040 sq. ft. of heating surface, 67 sq. ft. of
grate area, with a working pressure of 220 Ib. per sq. in.

909. Water- tube boiler with paraffin burner. Lent by the
Lune Valley Engineering Co., 1909. N. 2503.

This is a sectional example of a water-tube boiler in which a large
heating surface relative to the space occupied is obtained. It is designed to
burn vapourised oil, and, in combination with a light high-speed steam
engine, forms an alternative method of propulsion to the petrol motor, both
for cars and launches.

The boiler is of the type patented by Messrs. J. G-. A. Kitchen and
L. P. Perkins in 1902. It consists of a vertical central drum or steam
chamber, surrounded by coils of tubes of mild steel. Each coil contains
three turns, and has both ends in communication with the central drum,
into which the ends are expanded. This flexible arrangement of the tubes
provides for free expansion and contraction, and minimises the possibility of
leakage ; also cleaning or replacement of a coil can easily be effected. The
steam chamber is either supported from the top by ribs extending to the
outer casing, as in the example shown, or prolonged at the bottom, the
lower end forming a mud drum. An outer casing, consisting of sheet steel,
lined with non-conducting fire-proof material, surrounds the tubes.

The burner is of the type patented by Mr. Kitchen in 1900. The oil,
which is common paraffin, enters at the top of the burner by the vertical
pipe on the right, and thence passes through the coil and another vertical
pipe to the nozzle below. During its passage through the coil it becomes
vapourised and is lighted at the nozzle. The jet then impinges on the
dome-shaped deflector, over which it spreads in a thin film, and mixes with
the air necessary for combustion. Regulation of the size of the flame is
provided for by a needle, which projects through the nozzle, and is operated
by the hand lever shown. Movement of the needle also tends to clear the
nozzle of carbon. This is important, because the deposition of carbon from
petroleum vapour would choke the burner, and this would be a serious
objection to this method of steam generation for continuous use. To start
the burner, a little methylated spirit is lighted in the asbestos-lined tray
under the nozzle. This sufficiently warms the coil to allow of the oil feed
being slightly opened. It is stated that with this boiler and burner an
evaporation of 15 Ib. of water per Ib. of oil from and at 100 deg. C. can be


910. Model of the natural draught arrangements of H.M.S.
" Inflexible." (Scale 1 : 24.) Made by the Admiralty,
1889. N. 1826.

The " Inflexible " was a sea- going turret ship, built at Portsmouth in
1881. Her dimensions were : Displacement, 11,880 tons ; length, 320 ft. ;
beam, 75 ft.; draught, 25 '3 ft. She was propelled by twin screws,
driven by two-stage expansion engines, indicating 8,000 h.p., and giving a
speed of 13 -8 knots. Steam, at 60 Ib, pressure was supplied by 12 oval


boilers, giving a total of 36 furnaces, 829. sq. ft. of grate area, 22,288 sq. ft,
of heating surface, and weighing with water, uptakes, funnel, &c., 756 tons.

The model illustrates the method of supplying air to the boiler-rooms,
which have no forced draught arrangements. A complete stokehold is
shown and a portion of another, together with the middle-line bulkhead
between them. The complete stokehold contains two single-ended boilers,
which are placed with their backs against the wing passages, and one
double-ended boiler, which is placed parallel with and near to the middle-line

The fresh air is collected above the upper deck by cowl pipes, and then
led by air trunks to various parts of the stokehold. The cowl pipe A has a
lead terminating in front of one of the single-ended boilers, and another
terminating in front of one end of the double-ended boiler. The cowl
pipe B has a lead terminating at one end of the double-ended boiler, and
the other terminating in the next stokehold. The ash hoists also serve as

In consequence of the difficulty of arranging suitable cowl openings in
the upper deck, and in carrying air trunks from thence to the stokeholds,
it has always been requisite in large warships to fit fans to blow air into the
stokeholds. The system of closing in the stokeholds, since adopted, is an
expansion of this plan, but it permits a larger supply of air and also insures
that all air blown into the stokeholds shall pass through the furnaces.

911. Sectional model of forced draught arrangements in
Thorny croft torpedo boats. (Scale 1 : 12.) Made by the
Admiralty, 1889. N. 1829.

In a boiler of this kind there is abroad rectangular fire-box with considerable
height above the fire to allow for complete combustion. Below the fire-bars
is simply an ash-pit, so that the furnace is open or " dry bottomed." The
tubes are closely spaced, so that the water space of the boiler is small, and
the weight of the boiler in comparison to its heating surface is minimised.
As all parts except the barrel have to be closely stayed, the interior of the
boiler is not accessible for cleaning, so that the use of sea-water is impossible.
The coal consumption per sq. ft. of fire-grate varies from 80 to 100 Ib. per
hour, when supplied with forced draught at a pressure of sometimes as
much as 5 in. of water.

The boiler represented is isolated by means of bulkheads, and in addition
there are, worked across the boiler room, two more bulkheads of light air-
tight screens through which the ends of the boiler project about 18 in., thus
leaving but a small space in front of the boiler under air pressure.

The air is forced into the stokehold by fans, and enters the furnace
through the doors in the " protection box " in front of the ash-pit. These
doors are light and are hinged at the top to open inwards only ; the pressure
in the stokehold keeps them open, but in case of any steam escaping into
the furnace the doors act as flap valves, and confine it and any flame to the
ash-pit, whence they escape to the funnel.

912. Sectional model of forced draught arrangements in

Online LibraryScience Museum (Great Britain)Catalogue of the naval and marine engineering collection in the ... museum .. → online text (page 43 of 58)