Improvements in Means for Protecting Boilers, Pipes and the like from Corrosion.
Year: 1899

page_text: Date of Application, 18th July, 1899
Complete Specification Left, 4th Apr., 1900-Accepted, 7th July, 1900
PROVISIONAL SPECIFICATION.
Improvements in Means for Protecting Boilers, Pipes and the like
from Corrosion.
I, JOHN EBENEZER BOUSFIELD, of the Firm of G. F. Redfern & Co., The
General Patent Office, No. 4, South Street, Finsbury, in the County of Londou,
Patent Agents, do hereby declare the nature of this invention (a communication
to me by Henry S. Ross, of Engineer Club, 5th Avenue, New York, in the
United States of America), to be as follows:-
-
The object of my invention is to provide an improved means for protecting the
surfaces of boilers, pipes and other vessels or receptacles from being corroded
by the action of the fluids which may be in contact therewith.
It is well known that when dissimilar metals are placed in contact with each
other in a corrosive fluid, one of the metals will corrode rapidly while the other
remains intact or receives a deposit on its surface. This fact has been utilized
by placing zinc plates inside a boiler, pipe or other vessel.
Such use, however, is subject to great difficulties and disadvantages. When
the zinc has so far corroded as to be no longer effective, the boiler has to be
cooled down, and opened, and much delay, labor and expense are incurred in
removing the corroded zinc, and refitting the boiler with new zine plates, which
must be so fitted as to have a good or close metallic contact between the zinc
and iron. Otherwise, the contiguous surfaces will corrode and render the device
ineffective. There must be good metallic connection between the two dissimilar
metals such as the zinc and iron, and there must also be a continuous or
unbroken body of liquid between them to serve as a return conductor, otherwise,
corrosion will take place on the surfaces of both metals.
If a good metallic contact and a good liquid return conductor are established
and maintained between the two dissimilar metals, it is not necessary that the
metal which is to be consumed by corrosion should be actually situated inside
the boiler, pipe or other vessel to be protected. Iron or steel of which boilers
are made is easily corroded where moisture is present, unless protected by contact
with a more easily corroded metal.
My system consists in placing the zinc or other metal which is to be consumed,
in a receptacle external to the boiler or pipe, and in establishing between the
said zinc, and the interior wall, or surfaces, of the said boiler or pipe, by means
of a copper wire or other suitable metallic conductor, a connection in good
metallic contact, and by allowing free communication between the interior of
said boiler, or pipe, and the said external vessel, whereby the liquid in one is
in free connection with the liquid in the other, thereby establishing a good
liquid return conductor between the metal to be protected and the metal to he
consumed, means being provided for shutting off such liquid communication
when required

page_text: A simplified but effective form of my system easily applied to pipes, and to the
internal and external walls of vessels consists of a plug, shank or tube of brass,
provided with a tip or bolt of zinc, interlocking with the body of the said plug
by a joint or contact, which I thoroughly protect, or seal, by a grommet, gasket or
otherwise, from the entrance and attack of the corrosive substance in which the
said tip is placed, the said composite plug being adapted to be attached to, or
inserted into, or through the wall or other part of the boiler, pipe or other
vessel, in such a manner as to obtain a good and protected metal contact there-
with. This is very necessary as the slightest moisture present between the joint-
ing surfaces of the two dissimilar metals, where in close contact permits quick
corrosion of their surfaces, as the electrical current generated, seeks the shortest
circuit between the two metals, and any oxide formed on these surfaces quickly
stops the mild electric current generated, and all protection ceases, where this
occurs
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicant.
Improvements in Means for Protecting Boilers, Pipes and the like
from Corrosion.
I, JOHN EBENEZER BOUSFIELD, of the Firm of G. F. Redfern & Co., The
General Patent Office, No. 4, South Street, Finsbury, in the County of London,
Patent Agents, do hereby declare the nature of this invention (a communication
to me by Henry Schuyler Ross, of Engineer Club, 5th Avenue, New York, in
the United States of America), and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement:
The object of my invention is to provide an improved means for protecting the
surfaces of boilers, pipes and other vessels or receptacles from being corroded
by the action of the fluids which may be in contact therewith.
It is well known that when dissimilar metals are placed in contact with each
other in a corrosive fluid, one of the metals will corrode rapidly while the other
remains intact or receives a deposit on its surface. This fact has been utilized
by placing zinc plates inside a boiler, pipe or other vessel.
Such use, however, is subject to great difficulties and disadvantages. When
the zinc has so far corroded as to be no longer effective, the boiler has to be
cooled down, and opened, and much delay, labor and expense are incurred in
removing the corroded zinc, and refitting the boiler with new zinc plates, which
must be so fitted as to have a good or close metallic contact between the zine
and iron. Otherwise the contiguous surfaces will corrode and render the device
ineffective. There must be good metallic connection between the two dissimilar
metals such as the zinc and iron, and there must also be a continuous or
unbroken body of liquid between them to serve as a return conductor, otherwise,
corrosion will take place on the surfaces of both metals.
If a good metallic contact and a good liquid return conductor are established
and maintained between the two dissimilar metals, it is not necessary that the
metal which is to be consumed by corrosion should be actually situated inside
the boiler, pipe or other vessel to be protected. Iron or steel of which boilers

page_text: are made is easily corroded where moisture is present, unless protected by contact
with a more easily corroded metal.
According to one form of my invention I place the zine or other metal which
is to be consumed, in a receptacle external to the boiler or pipe, and establish
between the said zinc, and the interior wall, or surfaces, of the said boiler or
pipe, by means of a copper wire or other suitable metallic conductor, a connec-
tion in good metallic contact, and I allow, free communication between the
interior of said boiler, or pipe, and the said external vessel, whereby the liquid
in one is in free connection with the liquid in the other, thereby establishing a
good liquid return conductor between the metal to be protected and the metal
to be consumed, means being provided for shuttiig off such liquid communica-
tion when required.
A simplified but effective form of my system easily applied to pipes, and to the
internal or external surfaces of the walls of boilers or other vessels consists of a
plug, shank or tube of brass, provided with a tip or bolt of zinc, interlocking with
the body of the said plug by a joint or contact, which I thoroughly protect, or seal,
by a grommet, gasket or otherwise from the entrance and attack of the corrosive
substance in which the said tip is placed, the said composite plug being adapted
to be attached to, or inserted into, or through the wall or other part of the
boiler, pipe or other vessel, in such a manner as to obtain a good and protected
metal contact therewith. This is very necessary as the slightest moisture present
between the jointing surfaces of the two dissimilar metals, where in close
contact, permits quick corrosion of their surfaces, as the electrical current gene-
rated, seeks the shortest circuit between the two metals, and any oxide formed
on these surfaces quickly stops the mild electric current generated, and all
protection ceases, where this occurs.
In the accompanying drawings, I have illustrated convenient applications of
my invention.
"Figure 1 is a transverse section of a boiler of usual construction shewing my
improvements applied thereto.
Figure 2 is a section shewing the application of the invention to pipes and
small vessels.
Figure 3 is an elevation, partly in section, shewing a composite plug as adapted
to protect a part of a boiler or pipe,
Figures 4, 5 and 6 are elevations, partly in section, illustrating modifications
of the plug and tip.
A is the separable external vessel in which the zinc or other metal to be con-
sumed is placed. The size of this vessel depends; obviously, upon the work
required of it. In the use shewn in Figure 1, the vessel is large enough to
contain a number of zinc plates %, suspended in the liquid. In the form shewn
in Figure 2, where the zinc Z is in the form of a simple rod, the vessel A may be
made in the form of a cylinder, or pipe sufficiently large to allow free circula-
tion of the corrosive liquid around the rod.
B is the boiler or other vessel or pipe, the wall of which is to be protected.
When this boiler or vessel is of large size, as in Figure 1, connection therewith
of the vessel A, is preferably brought about by means of a pipe I provided with
a valve V and inserted between the vessel, and boiler, so as to allow free circu-
lation of the liquid therein when the valve is open. By closing the valve V,
the cover of the vessel A can be safely removed without disturbing the boiler or
its contents. When thus removed, the corroded zinc plates may be taken out
and fresh ones inserted or a new vessel already prepared with zinc plates may
be substituted without interrupting the use of the boiler.
The metallic and liquid contacts or conductors between the zinc and the
interior of the boiler consist as shewn of a wire W, which may be of any metal
which is a good conductor of electricity and heat, for the metallic contact or
conductor, and of the continuous body of liquid in the two vessels, and in the
pipe l', for the liquid contact, or return conductor.

page_text: I have found that one point of metallic contact to the internal plate or wall
of the boiler protects a contiguous surface of about four or five feet radially from
the said point of contact, and I have, therefore, shewn the wire W, as branching
and making various metallic contact points on the interior of the boiler, all of
which are covered and protected by cement or solder. I have shewn the wire
Was continuing through the pipe P but, if preferred, this pipe itself may be
made of suitable metal to serve as a portion of the metallic conductor. The
plates, are connected to the other end of this wire W inside the vessel A by
cement-covered, soldered, grommetted or otherwise protected joints J, J, J,
that the surfaces of such joints are not liable to corrosion.
When the vessel B is a small one, as shewn in Figure 2, the external vessel
A may be screw-threaded into an opening therein, as shewn. When the vessel B
is a continuous pipe, vessels such as A, should be placed at intervals of about
ten feet along the said pipe, each vessel protecting about five feet of the surface
of the pipe in each direction from the opening.
The metallic contact between the rod Z and the interior of the pipe or vessel B
is brought about as follows: A screw threaded cap G fits over the outer end of
the vessel A which, as shewn, may be a simple pipe and the rod Z may be simply
screw-threaded, to fit the interior of said cap. There is, therefore, obviously, a
metallic continuous contact from the rod Z through the screw-thread T, cap G,
and pipe A, to the metal to be protected in the interior of the vessel B. The liquid.
or return conductor is the continuous body of liquid surrounding the rod Z in
free communication with the liquid inside the vessel B (liquid not shown).
Obviously, by unscrewing the cap G, the zinc Z can be removed when needed and
a fresh zinc substituted. The joints between the vessel A and the cap G are care-
fully protected from the corrosive action of the liquid by a rubber or cement
gasket or by some other effective means.
Many modifications in the form of the external vessel, and in the means for
connecting it with the interior of the boiler or other vessel to be protected, can
be readily made without departing from the spirit of my invention.
It has long been known that corrosion can be prevented by placing in vessels,
pieces of zinc or other metal of a nature to corrode more easily than the metal
to be protected, and establishing clean metal contact between them. Many diffi-
culties have attended the commercial application of this well known fact, among
which may be mentioned the necessity of emptying the vessel when the corroded
joints and zinc have to be renewed, the short time during which the protection
remains effective, and the uncertainty of the various devices employed to obtain
good metallic contact.
My system overcomes these difficulties and others, and protects the exterior
and interior surfaces of pipes, etc., and further consists of a plug G, of brass,
or other comparatively non-corroding metal, and provided with a tip of zinc Z,
or other more easily corroded metal, interlocking with the body of the said
plug, by a joint, which is thoroughly protected or sealed by a grommet J, coat,
or otherwise, from the corrosive attack of the substance in which the said zinc
tip is submerged, or buried, said composite plug being adapted to be screwed into
or through the wall B, of a boiler, pipe or other vessel, in such a manner as to
obtain a good metal contact therewith.
B is a fragment of. the wall of a boiler, pipe or other vessel, the surfaces of
which are to be protected from corrosion. G is the body of the plug, which may
be made of brass, or other comparatively non-corroding metal. Z is the zinc tip.
When used in the form shewn in Figure 3, a plug is formed with an external
screw thread b, which engages with a thread cut in the opening in the wall B.
Where the tip screws into the body of the plug (as in Figure 3) a simple external
screw thread on the reduced end of the tip, and an internal thread on the plug
are sufficient, and the zinc Z is screwed into the plug, with a grommet J cover-
ing the opening to the threads, The projection h at the rear is provided for the
purpose of holding and forcing in the said plug.

page_text: Figure 4 illustrates a form with the plug screwed into the tip.
Figure 5 shews a plug with a rear projection threaded and screwed into the
pipe or vessel B.
When desired the projection can be placed at a right, or other desired angle,
as in Figure 6 to locate the zinc nearer the wall of the pipe B, or to be used
externally to the pipe B, as in mud or damp earth outside the said pipe B.
J is a grommet or gasket of rubber, cement or other impervious material which
serves to protect the joint made between the zinc tip and the brass plug. The
joint between the plug and the metallic wall of the vessel, I also protect in a
similar manner.
These plugs are to be inserted in the wall of the vessel at such intervals as may
be necessary for the thorough protection of its surfaces. Each plug by corroding
protects the surrounding wall for a radius which varies with the exposed surface
of the plug, and the intensity of the corrosive action present. It is better, how-
ever, to have smaller plugs at shorter intervals than larger plugs at larger
intervals. A plug with an effective protecting radius of three feet makes a con-
venient size and can be, of course, used at intervals of every six feet.
The protection of the joints, from corrosive attacks of the liquids which may
be present, is of very great importance, as will be readily understood when the
action which takes place is analyzed.
A current of a voltaic character is established through a circuit, of which the
metals of the plug and vessel, with their interlocking joints and a portion of the
corrosive substance, form parts. This current, however, is very gentle, and the
creation of even a slight resistance in the circuit, practically acts as a break in
the circuit, causing the current to cease flowing. This resistance is created by
even a slight amount of oxidization at any of the joints; and this oxidization
is sure to take place if the contained fluids have access to the joints made by the
dissimilar metals. A gasket, coat or ring of cement or other non-corroding
material, which extends over all of these joints wherever they would otherwise be
subject to contact with the corrosive liquid, I have found to be an effective way of
securing protection of the joints, so positively necessary to maintain the negative
polarity of the iron of the boiler or pipe to be protected. A practical application
of my system of maintaining the integrity of the jointing surfaces of the two dis-
similar metals and therefore the polarity of the vessel to be preserved from corro-
sion, is, when zinc plates are secured to plates of iron or other metal to preserve
the latter from corrosion when immersed in water, to rabbet, groove or chamfer
the edge of the plate of zinc nearest to the plate of iron, calking or filling such
groove with lead, cement, rubber or other protecting material to prevent moisture
from entering between the zinc and iron and corroding the contiguous surfaces.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:―
1. The herein described means for protecting boilers, pipes and the like from
corrosion comprising a special receptacle, containing zinc, which zinc is connected
by wires, and a confined body of liquid, to different parts of the boiler or vessel
to be protected from corrosion, with means for shutting off said liquid com-
munication, and insulating the joints between dissimilar metals.
2. In means for protecting boilers, pipes and the like from corrosion a closed
branch-tube, containing zinc, both of which are connected electrically with the
pipe or vessel to be protected from corrosion, the joints between dissimilar metals
being insulated, substantially as set forth.
3. A system consisting of zinc, connected electrically with a vessel to be pro-
tected from corrosion, wherein the surfaces of adjoining dissimilar metals are
protected from moisture, substantially as set forth.
4. In means for protecting boilers, pipes and the like from corrosion, a plug
or holder of comparatively non-corroding metal, provided with means for securing

page_text: it in electrical contact with the boiler or other vessel, a tip of more easily cor-
rodible metal secured thereto, and in metallic contact therewith, and means for
covering the joint between the plug or holder and the tip to protect it from
moisture, substantially as set forth.
Doted this 4th dove of Anril *1000
G. F. REDFERN & Co.,
4, South Street, Finsbury, London,
Agents for the Applicant.