August 16, 1918.

THE COLLIERY GUARDIAN

337

the blow-off pipe (as well as at places covered by brick-
work), because these parts are often very damp, in
some cases owing to leakage from the water gauges,
and often because the fireman slakes his ashes against
the front end plate, a practice which not only corrodes
the plate, but which leads to dampness in the blow-
out pit and consequent wasting of the bottom of the
shell in the vicinity of the blow-out pipe. An example
of wasting at these parts is given in fig. 8.

The external examination should include a search
for evidences of leakage at the seams, since any leakage
may give rise to serious wasting of the adjacent plate,
particularly if the plate is covered by brickwork.

Occasionally, more or less severe wasting is found in
the furnace tubes, about the level of the firebars, more
especially when the coal used for firing contains
sulphur. In more than one instance we have found
the upper portion of the first and second rings, and

Fig. 4.

Fig. 5.

Fig. 6.

especially the second ring, extensively wasted almost
over the entire length, and in one instance the bend
of the flange facing the flow of gas was found, on
being drilled, to have been reduced to 1116 in. The
wasting is of a smooth character, and is difficult' to
detect. The flange facing the front end is naturally
the part most liable to suffer, and it is a good plan
to examine the uppermost and the lowermost portions
of the flange, because if any wasting has taken place,
the radius of the former portion will be much larger
than that of the latter.

Fig. 9 illustrates the defect under consideration, and
will serve to show how the radius of the flange on the
fire side is increased by the wasting effect.

Other external defects, in addition to those men-
tioned, are grooving, bulging, and distortion of the
plates, blisters and laminations.

External grooving is purely a wasting of the outer
surfaces of the plates into the form of a groove. It
is found at the riveted seams and round the flanges -
of the mounting blocks on the shell, particularly
round the blow-out and the manhole blocks, and is
an evidence of leakage.

Bulging and.distortion of the plates should be looked
for principally about the furnace tubes and at parts
of the shell, if there be any, where the plate is not
protected from the heat by the water, In some
instances the flue covers have been raised well above
the water level with the object of obtaining more
heating surface, with the result that the portion of the
flat back-end plate unprotected by the water has
become badly bulged. This raising of the flue covers
has also led to severe internal wasting of th© shell
just above the water level.

When heavy accumulations of scale and deposit are
allowed to form in the boiler, bulging of the bottom of
the shell in the vicinity of the blow-out block is liable
to result from local over-heating. The remedy is
obvious.

Serious bulging is most likely to be found in the
upper portions of the furnace tubes. At every external
examination it is advisable to gauge the diameter
of the tubes, both vertically and horizontally, at two
or three places, with the object of finding out if the
true circular shape has been altered under working
conditions. A slight ovality will seriously reduce the
strength of the tubes to resist collapse.

Blisters and laminations are not as a rule serious
defects; they should be looked for principally about the
furnace, where the heat is most intense.

Preventing Deterioration,

The engineer who makes a practice of frequently
examining the boilers under his charge may play a
most important part in prolonging the life of the
boilers. Defects will sometimes develop shortly after
the annual inspection by the boiler insurance com-
pany, and, before the next insurance inspection, may
become serious, involving risk in working and neces-
sitating expensive repairs. Supplementary examina-
tions will serve to discover such defects at an early
stage, so that they can then be attended to immediately.

A further advantage of these supplementary exami-
nations is that they enable the engineer to find out
if the boilers are being worked under the best con-
ditions. The discovery of wasting at the lower part
of the front end plate, for example, would at once
call his attention to the fact that the fireman was
neglecting to keep the front of the boiler quite dry
at all times, and the necessary steps to prevent an
extension of the trouble could be taken without delay.

In order to apply a suitable remedy for a defect, it
is necessary to know the cause of the trouble. Except
in the case of external corrosion, we have not explained

how the various defects considered are brought about.
It would be interesting, and no doubt useful, to discuss
the causes in detail, but, owing to limitations of space,
we cannot do more than make a brief reference to
them.

Internal corrosion is generally caused by the acid
action of the feed water. In colliery districts the
highly coloured water known as “-ochrey ” water is
much used for feeding the boilers. This is extremely
corrosive, and frequently gives rise to rapid wasting
of the plates. Whenever possible a water free both
from corrosive ingredients and scale-forming matter
in solution should be used. If a pure water be not
obtainable, the available water should be suitably
treated (preferably outside the boiler) by the correct
chemical reagents, which can only be determined after
making an analysis of the water.

If internal treatment be adopted, frequent cleaning
is necessary. It should not be forgotten that the addi-
tion of chemical reagents to the water will not remove
scale, but merely render it soft so that it can be
removed without difficulty.

Grooving, although generally regarded as a form of
internal corrosion, is really a mechanical defect, but
it is in most cases aggravated by the corrosive action
of the feed water. A piece of thin plate, if bent re-
peatedly backwards and forwards, will soon fracture
and break. In the same way a piece of thick boiler
plate, if exposed to the same action, will in time
develop a fine fracture or groove. Under working
conditions, the skin of the metal is first broken, and
if the water be corrosive, the metal, in addition to
being broken, is corroded, a round groove being
formed. With pure water no corrosion occurs, and
the groove resembles a fine fracture. To prevent the
trouble, the boiler must be so designed that expansive
movements may be satisfactorily accommodated; that
is to say, the parts of the boiler at which the move-
ments are principally concentrated must be more or
less elastic. In large high-pressure Lancashire boilers
it is a difficult problem to provide the necessary
strength and at the same time make the structure
sufficiently elastic to prevent grooving.

Fractures may result either from improper methods
of construction or from unsatisfactory conditions of
working. In modern boiler-making, the workmanship
has reached such a state of perfection that it is seldom
a fracture is set up during construction. It is the
boiler attendant rather than the boiler maker who
is nowadays mostly responsible for fractures.

A golden rule in boiler maintenance is this : “ Avoid
sudden changes of temperature.” The atomic forces
set up in the plates as a result of sudden cooling are
practically irresistible, and may lead to fracture of
shell plates as much as 1 in. thick. The importance,
therefore, of avoiding all practices which lead to rapid
cooling of the hot plates, such as leaving open the
fire doors and so admitting large quantities of cold
air into the furnaces, introducing cold feed water
in a solid jet in close proximity to the plates, cooling
down the boiler rapidly for cleaning and inspection,
and so on, will be obvious.

Heavy accumulations of scale, by causing overheating
and consequent straining, will increase the tendency
to fractures, as also will the presence of grease in the
boiler. Bulging, distortion, and collapse of the plates

Fig. 8.

Fig. 7.

Fig. 9.

may be caused by scale and grease, as well as by
shortness of water. When scale and grease are re-
sponsible for the trouble, the upper side portions of
the tubes are the parts which generally suffer.

External corrosion, as already explained, is caused
by damp in contact with the plates. It is perhaps
easier to prevent than any other defect, all that is
usually required being to keep the external surfaces
of the plates quite dry, both when the boiler is at
work and at rest. To reduce the tendency to external
corrosion, the width of all parts of the setting which
bear against the plates should be reduced to the
minimum. The best type of setting is one which pro-
vides rounded blocks for every part of the boiler which
bears against the brickwork. With "Acme” or
“ Poulton ” blocks, for example, practically no surface
of plate is covered over; the maximum amount of
heating surface is obtained, and the boiler can be fully
examined externally without removing any brickwork
whatever.

Whilst the engineer can train himself to discover
defects for himself, he can scarcely be expected to
decide if any particular defect is sufficiently serious
to necessitate immediate attention. This is the special
work of the boiler insurance company, and should
generally be left to them.

The question as to whether or not a boiler is quite
safe to work at its stipulated working pressure is
for the chief engineer of the insurance company to
decide, but there can be no doubt that independent
examinations made by the firm’s engineer are often
of the greatest assistance to the insurance people, whilst
they are certain to play a most important part in
prolonging the working life of the boilers and in
reducing to the minimum the cost of maintenance and
upkeep.

NORTH OF ENGLAND INSTITUTE
OF MINING AND MECHANICAL
ENGINEERS.

In the absence of the president (Mr. John Simpson),
Col. Frank Coulson, a past president, occupied the
chair at the annual meeting of members of the North
of England Institute of Mining and Mechanical
Engineers, held in the lecture theatre of the Wood
Memorial Hall, Westgate-road, Newcastle-upon-Tyne,
on Saturday afternoon last.

The council reported having decided that any case of
a naturalised or unnaturalised alien member’ reported
to it should be dealt with on its merits. It had been
agreed also that a slip should be attached to all nomi-
nation forms on which nationality must be stated by
candidates for membership. The use of the lecture
theatre had been refused to a society on the ground
that the use of the theatre was only granted to scientific
societies, whereas the society in question was of an
industrial character.

Annual Report.

Mr. Reginald Guthrie, treasurer, reported, on
behalf of the finance committee, that the receipts for
the year ended June 30 last, including £213 received
for returned income tax, were £2,971. The amounts
received for subscriptions totalled £2,397, as against
£2,344 for the previous year, and the interest on invest-
ments was £392, as against £390. The expenditure
was £2,480, as against £2,357. The balance of income
over expenditure was £490.

The report was adopted, on the motion of the
Chairman, seconded by Mr. C. C. Leach. Mr. Leach
said, re the motor ambulances, that on receipt of
the cheque for £422 10s., Capt. Sir H. Dennis Bayley
wrote that the ambulances, along with all the others
provided by the coalowners and miners, had been
exceedingly busy in doing splendid work; he was very
glad to have the cheque, which would enable them to
continue their good work, and wished to thank the
institute and members for it.

The annual report of the council recorded the deaths
of Prof. G. A. L. Lebour, who was elected a member in
the year 1873, and an honorary member in 1879, served
on the council from 1880 to 1888, and acted as secretary
from 1888 to 1891 ; Mr. W. Armstrong, wfio was elected
a member in 1867, became a member of the council in
1875, a vice-president in 1897, and was elected president
in 1898; and Mr. Simon Tate, who was elected a
member in 1875, a member of the council in 1891, and a
vice-president in 1917.

The following members have been killed in the war:—
C. P. Almond, W. E. Avery, D. M. Chambers, B. H.
Charlton, S. Coade, J. Heslop, G. H. S. Kent, C. F. B.
Simpson, T. A. Thirlwell, F. Thornton, F. M. Weeks,
M. H. Wilkinson, and C. Young; and the following
have died:—The Duke of Northumberland, and Messrs.
J. W. Ainsworth, P. Archer, C. R. Barrett, H. Bigg-
Wither, D. Cullen, S. Dean, W. Dixon, J. Douglas,
C. Henderson, R. Kondo, J. Lancaster, H. Latimer,
R. Peel, and J. H. Walker.

The resignations numbered 17, and eight other
gentlemen ceased to be members. In contrast to 1917,
when the membership increased by 43, there was a
decrease of nine, the total number of members being
1,194.

A list of members serving with his Majesty’s forces
at home and abroad is being compiled, and, in order to
make this as complete as possible, the council will be
pleased to be advised of any member serving.

The institute’s library was augmented by 84 bound
volumes and 17 pamphlets, reports, etc.; and now con-
tains about 15,874 volumes and 622 unbound pamphlets.
At the suggestion of Captain H. Dennis Bayley the
institute subscribed £100, and the members also
contributed £322 10s. towards the upkeep of tbe
motor ambulance purchased in 1916. The Saturday
afternoon lectures for colliery engineers, engine-
wrights, and apprentice mechanics arranged to take
place at Armstrong College were still suspended on
account of the war. Mr. T. Douglas continued to
represent the institute as a governor of Armstrong
College, and Mr. J. R. R. Wilson, in conjunction with
the president (Mr. J. Simpson), represented the
institute on the council of the College. Mr. T. Y.
Greener was appointed to represent the institute upon
the board of directors of the Institute and Coal
Trade Chambers Company Limited; and the pre-
sident continued a representative governor upon tbe
Court of Governors of the University of Durham
College of Medicine during bis term of office.

No application was made for the “ Daglish” Fellow-
ship for the year 1918. G. C. Greenwell silver medals
were awarded to Mr. Fang Chun Lee for “Some
Practical Notes on the Economical Use of Timber in
Coal Mines,” and to the late Mr. Simon Tate for
“ Further Notes on Safety Lamps.” Prizes were
awarded to the writers of the following papers, com-
municated to the members during the year 1917-
1918 :—“ A System of Storing and Filling Small Coal,
with Remarks upon the Prevention of Spontaneous
Heating in Coal Heaps,” by Mr. J. Morison, M.I.M.E.;
“ Notes on the Overhead Koepe Winding Plant at
Plenmeller Colliery, Haltwbistle, Northumberland,”
by Mr. G. Raw, M.LM.E. The institute received a
legacy of £500 from the executors of the late George
May, the income from which is to be used for pur-
chasing a prize or prizes to be given annually to any