IMPROVEMENTS IN BOILERS OR VESSELS EMPLOYED IN THE TREATMENT OF FIBROUS MATERIALS FOR THE MANUFACTURE OF PAPER PULP OR FOR OTHER PURPOSES " PROAL SPATION
Year: 1883

page_text: LETTERS PATENT to Isaac Shimwell McDougall of the firm of McDougall
Brothers, of Manchester in the County of Lancaster Manufacturing Chemist,
for an Invention of "IMPROVEMENTS IN BOILERS OR VESSELS EMPLOYED IN
THE TREATMENT OF FIBROUS MATERIALS FOR THE MANUFACTURE OF PAPER
PULP OR FOR OTHER PURPOSES
"
PROVISIONAL SPECIFICATION left by the said Isaac Shim well McDougall
at the Office of the Commissioners of Patents on the 30th Juno 1883.
ISAAC SHIMWELL M°DOUGALL of the firm of McDougall Brothers of Manchester
in the County of Lancaster Manufacturing Chemist "IMPROVEMENTS IN BOILERS
OR VESSELS EMPLOYED IN THE TREATMENT OF FIBROUS MATERIALS FOR THE
MANUFACTURE OF PAPER PULP OR FOR OTHER PURPOSES
"
My Invention relates principally to boilers or vessels which are employed for the
treatment of fibrous materials in the manufacture of pulp for paper making and
which are lined with lead but my said Invention is also applicablo to lead lined
vessels for other purposes.
In such lead lined vessels a considerable difficulty has hitherto been experienced
in keeping the lead in its relative position with the casing when the boiler or
vessel is submitted to high temperatures.
The repeated action of heat upon the lead causes it to continually increase in
area and thus gradually accumulate into ridges or creases which soon break and
necessitate the relining of the boilers or vessels.
Most metals such as steel and iron expand when heated and return to their
original volume on cooling-Lead does not possess this power of returning to its
original area after expansion-The particles of lead are supposed to possess an
amount of adhesive friction which prevents their contraction to an extent equal to
that to which they have expanded For this reason it is difficult to make lead
lined boilers or vessels durable when required to withstand high temperatures.
By this Invention the lead lining of boilers or vessels is made durable by

page_text: providing an arrangement for securing the lead lining to the boiler or vessel in such
a manner that the creeping or sliding effect of the lead is localized into sufficiently
small portions to make the lead lining much more durable for the use of pulp
Boilers or for other purposes-this according to my Invention I accomplish by
providing a sufficient number of suitable holes through the casing and corresponding
holes in the lead lining and passing through both these holes bolts or fastenings
having a head or the like on the inside and having one or more nuts or other
means on the outside for tightening and holding the lead lining and the outer
casing firmly together so as to hold the lead lining in position to the casing―These
bolts or fastenings should by preference be fixed at distances not very far apart say
at about from nine to twenty four inches in every direction according the
_thickness_of_the_lead_lining used and the temperature to which the vessel is
required to be subjected but I do not limit myself to these distances.
Where preferable a washer or washers or metal strips or bands may be placed
beneath the heads or the like of the bolts or fastenings to form a wider holding
surface on the lead lining and these bands or strips may if desired be passed from
bolt to bolt or to any convenient number of bolts or fastenings-As a means to
protect the bolt heads or the like or the metal washers strips or bands beneath the
bolt heads from the chemical action of acids the heads of the bolts or other exposed
metal surfaces are covered over with lead which may be burned or melted to the
lead lining thus causing the inner surface of the vessel to be one complete lead
lining or surface of lead firmly and securely held to the outer casing in such a
manner that the creeping action of the lead is localized into limited portions
whereby the durability of the lead lining is greatly enhanced

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Isaac Shimwell M°Dougall in the Great Seal Patent Office on
the 28th December 1883.
ISAAC SHIMWELL MODOUGALL of the Firm of MoDougall Brothers of Manchester
in the County of Lancaster Manufacturing Chemists IMPROVEMENTS IN BOILERS
OR VESSELS EMPLOYED IN THE TREATMENT OF FIBROUS MATERIALS FOR THE
MANUFACTURE OF PAPER PULP OR FOR OTHER PURPOSES
33
My Invention relates principally to Boilers or vessels which are employed for tho
treatment of fibrous materials or the manufacture of pulp for paper making and
which are lined with lead but my said Invention is also applicable to lead-lined
vessels for other purposes.
In such lead-lined vessels a considerable difficulty has hitherto been experienced
in keeping the lead in its relative position with the casing when the boiler or vessel
is submitted to high temperaturos.
The repeated action of heat upon the Lead causes it to continually increase in
area and thus gradually accumulate into ridges or creases which soon break and
necessitate the relining of the boilers or vessels
Most metals such as steel and iron expand when heated and return to their
original volume on cooling. Lead does not possess this power of returning to its
original area after expansion. The particles of Lead aro supposed to possess an
amount of adhesive friction which prevents their contraction to an extent equal to
that to which they havo expanded. For this reason it is difficult to make load
lined boilers or vessels durable when required to withstand high temperatures.
The object of my Invention is to render the Lead lining of boilers or vessels
durable by providing an arrangement for securing the lead lining to the casing
of the boiler or vessel in such a manner that the creeping or sliding effect of the
lead is localized into sufficiently small portions to make the lead lining much more
durable for use in boiling paper pulp or for other purposes-According to my said
Invention I accomplish this by providing a sufficient number of suitable holes
through the casing and corresponding holes in the lead lining and passing through
both these holes bolts or fastenings having a head or the liko on the inside and
being provided on the outside with one or more nuts or other means for tightening
or holding the lead lining and the outer casing firmly together so as to hold the
lead lining in position to the casing-Those bolts or fastenings should by preference
be fixed at distances not very far apart say about from nine to twenty four inches
in every direction according to the thickness of the lead lining and the temperature
to which the vessel is required to be' subjected but I do not limit myself to theso
distances.
Where preferable a washer or washers or metal strips or bands may be placed
beneath the heads or the like of the bolts or fastenings to form a wider holding
surface on the lead lining and these bands or strips may if desired be passed from
bolt to bolt or to any convenient number of bolts or fastenings. The bolts may be
made of metal which will resist the action of Acids or when made of other metal
the heads of the bolts or the metal washers strips or bands beneath the bolt heads
may be protected from the chemical action of Acids by covering the heads of the
bolts or the other exposed metal surfaces with lead which may be burned or melted
to the lead lining thus causing the inner surface of the vessel of lead to bo firmly
and securely held to the outer casing in such a manner that the creeping action of
the lead is localized into limited portions whereby the durability of the lead lining
is enhanced.

page_text: As a further means of protecting the lead lining from unnecessary strain caused
by gases condensing within the vessel a valve may be so arranged as to open when
the pressure of the atmosphere exceeds that within the vessel, thus preventing the
formation of a vacuum.
Having now described and particularly ascertained the nature of my said
Invention and the manner in which the same is or may be used or carried into
effect I would observe in conclusion that what I consider to be novel and original
and therefore claim as the Invention 'secured to me by the hereinbefore in part
recited Letters Patent is :-
".
Attaching the lining of lead-lined boilers or vessels for boiling paper pulp
or for, other purpose substantially in, the manner and for the purpose hereinbefore
described
In witness whereof I the said Isaac Shimwell McDougall-have-to-this-my-
Specification set my hand and seal this twenty fourth day of December One
thousand eight hundred and eighty three.