GASKETING OF PLATE HEAT TRANSFER APPARATUS

JOINTS ETANCHES POUR ECHANGEUR DE CHALEUR A PLAQUES

English Abstract

A B S T R A C T
Title - Gasketing of Plate Heat Transfer Apparatus
In heat transfer apparatus of the plate type, gaskets
around the plates are normally elastomeric gaskets fixed by
adhesive into pressed recesses in the plates. These gaskets
are expensive and the technique of fixing and replacing them
is time consuming. In accordance with the present invention,
a pressed groove 2 in a plate 1 is filled with a body 4 of
plastics material having the capacity of adherence to the
metal of the plate 1. This body 9 of plastics material is
then formed with an accurate groove 10 to receive and mechanically
retain a seal 11.
The groove 10 and gasket 11 may be duplicated to form a
double seal.
FIGURE 2.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a metal heat transfer plate having a pressed groove:
the improvement that the pressed groove which is at least partially
filled with a plastics material which adheres to the plate
metal and which is formed with an accurate recess to receive
a preformed seal of appropriate type.
2. A heat transfer plate as claimed in claim 1, in which
the plastics material is formed with at least two accurate
recesses to receive seals so as to provide a double or multifold
seal between the flow spaces and the ambient.
3. A heat transfer plate as claimed in claim 2, in which
the space between the gaskets of the double seal is monitored
for leaking fluid.
4. A heat transfer plate as claimed in claim 3, in which
the monitoring is achieved by means for circulating a fluid
through the space.
5. In a method of forming an gasket recess in a pressed metal
plate, the improvement that an accurately profiled recess is
formed by the steps of forming a pressed groove in the metal
plate, at least partially filling the pressed groove with a
plastics material which adheres to the metal of the plate, and
accurately forming the gasket recess in the plastics material.

6. A method as claimed in claim 5, in which at least two
parallel gasket recesses are formed in the plastics material.
7. A method as claimed in claim 5, in which the gasket recess
is accurately formed by moulding the plastics material.
8. A method as claimed in claim 5, in which the gasket recess
is accurately formed by machining the plastics material.

Description

1~A,>5~7;~9
Title: Gasketing of Plate Heat _ransfer apparatus
This invention relates to the gasketing of plate heat transfer
apparatus.
A plate heat transfer apparatus, i.e. either a plate heat exchanger
or a plate evaporator, consists of a series of plates arranged
spaced face-to-face relationship to form flow spaces between
the plates. The boundaries of the flow spaces are formed and
sealed by gaskets which are normally mounted in grooves pressed
into the plates. The gaskets are normally of a rubber or rubber-like
material and are retained in their respective grooves by adhesive.
The initial mounting of the gaskets in the grooves is a fairly
time consuming process involving surface preparation, application
of adhesive, location of the gasket in the groove and probably
curing of the adhesive. ~hen the gasket needs to be replaced,
the old gasket has to be stripped out, the metal surface cleaned
of old adhesive and then the new gasket has to be mounted with
all that entails.
If, instead of being pressed, the gasket recesses were precision
machined grooves, the sealing could be more easily obtained
by using preformed O-ring, lip or other similar seals which
would be a close mechanical fit in the grooves and would therefore
not need to be retained by adhesive. However, when using the
usual metal thickness le.g. 0.7mm) of plate heat transfer apparatus,
precision machining of grooves is not practicable and for many

11~573!~
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years the use of adhesive has been the normal practice in the
industry.
.
According to the present invention there is provided a heat
transfer plate having a pressed gasket groove which is at least
partially filled with a plastics material which adheres to
the plate metal and which is formed with an accurate groove
adapted to receive, or receiving, a preformed seal of O-ring,
lip or other appropriate type.
According to a second aspect of the invention, there is provided
a method of forming an accurately profiled gasket recess in
a pressed metal plate comprising the steps of forming a pressed
recess in the metal plate, at least partially filling the
pressed recess with a plastics material which adheres to the
metal of the plate, and accurately forming a gasket recess
in the plastics material
The gasket recess may be formed by moulding or by machining
the plastics material.
By using an intermediate filling of plastics material permanently
attached to the plate metal, no adhesive is required to attach
the sealing gasket, conventional commercially available gasket
forms may be used, the gasket loading may be reduced, which
leads to easier tightening of the frame of the heat transfer
apparatus, the application of the gasket can be automated more

~1~5733
. 3 --
easily and the replacement of gaskets is facilitated.
The invention will be further described with reference to the
accompanying drawings, in which :
Figure 1 is an elevation of a form of heat exchanger plate in
accordance with a form of the present invention and having a
double seal gasket;
Figure 2 is a section on the line II-II of Figure 1; and
Figures 3 and 4 are each diagrammatic sections similar to Figure
1 showing a form of single seal applied according to the techniques
of the present invention.
Turning first to Figure 1, a heat exchanger plate is illustrated
at 1 and as having four corner ports 2, 3, 4 and 5. The line
of a peripheral gasket, of double seal form is indicated at 6,
and it will be noted that the corner ports 4 and 5 also have
port gaskets 7, also of double seal nature.
Figures 2 to 4 each show a portion of the heat exchanger plate
1 as being provided with a pressed in gasket recess 8.
; In order that this recess 8 may be converted to a form sufficiently
accurate for a preformed seal 6, it is filled with a plastics
~aterial 4 which has the property of adhering to the metal of

, 33
the plate 1 and which is formed, either by pressure moulding
or by machining~ or a combination of both, with an accurately
formed recess 10 to receive the seal.
The plastics material may for instance be that sold as 'keebush'
or 'keeglass'. These materials have the property of adhering
to the plate metal, are as flexible as the plate pressing and
will withstand attack from a wide range of chemicals over a wide
range of temperatures. In addition, these materials are hard
and machinable. The plastics material is mixed and positioned
in the groove 2 and can be moulded under pressure so as simultaneously
to fix it in the rubber groove and to form a suitably profiled
recess 10, for the seal. Alternatively, the plastics material
can be roughly sculptured and, when cured, machined to form the
final shape of the recess 10.
In Figure 3 the seal is shown in the form of a single O ring
seal 12.
In Figure 4, the O-ring seal 12 is shown as being replaced by
a lip seal 13.
In accordance with a preferred form of the present invention,
Figure 2 shows a construction in which the filling 9 is formed
with a pair of such recesses 10, each of which is shown as receiving
an O-ring seal 11 to form the double seal. The configurations
of the port gaskets 7 may be similar.

573
-- 5 --
It will be appreciated that when dealing with hazardous fluids,
a seal of this nature is beneficial, especially if the space
between them is monitored for leakage of the hazardous fluid
so that this leakge is detected before the hazardous fluid leaks
passed the second seal into the ambient atmosphere. For this
purpose, the space between the two seals 11 may have an appropriate
fluid pumped through it and in circuit with a detector to detect
the presence of the hazardous fluid in the diluent. Suitable
micro-bore piping may be used to make the connections.
Various modifications may be made within the scope of the invention.
Thus, although the grooves 10 of Figure 2 are shown as receiving
O-ring seals, lip or other seals could be used instead.