COMMISSIONER'S DECISION
Obviousness: Metallic Seal Ring
The invention was for an annular seal ring comprising a "C"-shaped
cross section of upper and lower disc members joined by a hinge member.
In use the hinge is capable of "plastic" deflection, while the disc
members are "elastically" deflectable. Utilization of both plastic and
elastic deformation is not taught in the prior art.
Rejection: Reversed
The Final Rejection of application number 127,281 (Class 277/66),
assigned to Fisher Controls Company Inc. and entitled "Metal Seal For
A Control Valve And The Like" was referred to the Patent Appeal Board
for consideration. There was a hearing before the Board on October
Z9, 1975 at which Mr. I. Fincham, Mr. E. Fincham and Mr. M. Cornwell
of Fisher Controls Company Inc. represented the applicant.
The invention relates to a metallic seal ring for use with control
valves where temperature and pressure variations result in substantial
thermal expansion and contraction of the component parts. The ring is
so constructed that when properly fitted between mating pipes (and the
like) it provides a better seal which does not leak.
In the Final Action the examiner refused the application for failing to
define any patentable subject matter over the following reference:
Br. Pat. 362,689 Dec. 10, 1931 Boyce et al
In that action the examiner stated (in part):
The rejection of claims 1-4 inclusive is maintained and the
reason for such rejection is lack of patentable subject matter
in view of the applied reference and obviousness. The cited
British patent discloses a metal seal having the same structure
as claimed by applicant. Applicant argues that the ring of
the cited British patent preferably employs an auxiliary ring 7
to prevent plastic deformation, whereas applicant's claimed
seal ring employs a hinge portion capable of substantial plastic
deformation. It is conceded that these differences do exist.
However it is contended that the seal ring of the cited Boyce
et al patent could experience substantial plastic deformation, if
the auxiliary ring 7 were not in place. It is concluded that
Boyce et al knew that plastic deformation would occur with that
particular seal ring structure and therefore utilized the auxiliary
ring to prevent its occurrence. The mere deletion of an element
with its corresponding function, in this case the auxiliary ring
7 and its prevention of plastic deformation of the seal ring, is
not a patentable step. There is no unusual or unexpected result
occuring from this deletion and therefore no patentable difference
exists. It is obvious that the ratio of the thickness of the hinge
portion to that of either of the thicker portions of the seal ring of
the cited patent is less than one. Applicant states in the disclosure
that it is preferable to use for "Inconel 718" a ratio of one
to eight. But applicant does not show anything inventively different
for that particular ratio in relation to all other ratios less than
one. Therefore claims 1-4 inclusive are obvious.
The applicant in his responses to the Final Action dated February 7, 1975,
February 10, 1975, and April 14, 1975, stated (in part):
To overcome the above deficiencies of known seals, applicant has
discovered that self-sealing metallic seals may be utilized not-
withstanding substantial temperature cycling off the mating parts
between which it is confined. In particular, applicant has dis-
covered that metal seals male be designed wherein a portion of the
seal undergoes elastic deflection while a further portion of the
seal undergoes plastic deflection.
The Examiner, in rejecting the claims in the instant application,
has conceded that differences between the seal of applicant and
the seal of Boyce et al do exist. These differences are clearly
defined in claim 1 presently in the case and thus, it is believed that
there is no dispute that claim 1 defines over the seal disclosed
in the cited reference. In particular, applicant claims a seal
having a hinge portion capable of substantial plastic deformation
while Boyce et al utilizes an auxiliary ring which, for all intents
and purposes, prevents plastic deflection.
However, the Examiner has hypothesized that Boyce et al knew that
plastic deformation would occur with that particular seal ring
structure disclosed and therefore has utilized the auxiliary ring
to prevent its occurrence. In this connection, applicant submits
that if Boyce et al knew about plastic deformation of seals, it was
to the extent, and only to the extent, that it is common knowledge
that a metallic material will bend if sufficient force is applied.
This is indicated by the statement in Boyce et al at page 1, lines
40-43, that
Preferably, in order to safeguard against distortion
of the cup ring beyond the elastic limit, an auxiliary
ring is provided.
This would seem to indicate that Boyce does recognize that
plastic deformation will occur beyond the elastic limit.
This naturally raises the question as to why Boyce et al,
if he knew about plastic deformation, would employ an auxil-
iary ring which bridges the cup walls and prevents their
collapse under the compression to which they are subjected.
In this respect, it must be pointed out that the seal of
applicant's invention represents a substantial improvement
over prior art seals in that, in use, where is provided a
leak-proof seal notwithstanding substantial temperature cycl-
ings of the mating parts between which it is confined. Thus,
although Boyce et al may have understood plastic deformation
in the sense that it was known metal will bend if sufficient
force is applied, he did not recognize how to employ such
plastic deformation in constructing a seal ring. Indeed, if
he did recognize the advantages of utilizing plastic deformation,
no auxiliary ring would be provided.
...
It will furthermore be noted that the claims of Boyce et al
clearly define a seal or joint wherein the outer surfaces are
convex to the corresponding sealing surfaces of the parts to
be joined. It is respectfully submitted that a reasonable con-
struction of the specification of the cited reference can only
lead to the conclusion that the improvement in seals which was
made by Boyce et al is clear from his statement on page 2, line 40,
in which he states:
Preferably, in order to safeguard against
distortion of the cup ring beyond the elastic
limit, an auxiliary ring is provided which
bridges the cup walls and prevents their
collapse under the compression to which they
are subjected.
As may be seen from the above excerpts from the reference of Boyce
et al, clearly the patentee was not dealing with the same problem
as is applicant.
...
The state of knowledge axisting in the prior art is that shown
in British patent 362,689. This patent specifically teaches that
an auxiliary ring must be provided to prevent plastic deformation.
The teachings of this reference are in a direction diametrically
opposed to the teachings and structure of the seal ring of the
instant application. Therefore, it is respectfully submitted that
with the teachings of Boyce et al directing one away from a structure
as claimed in the instant application, one knowledgeable in the
art would not know that, not only can a seal without the auxiliary
ring be employed, but that such a seal presents significant
advantages.
In further support of the above, applicant is enclosing here-
with an Affidavit sworn by Mr. Charles Jackson, a registered
professional engineer in the State of Texas, United States
of America. As outlined in his Affidavit, Mr. Jackson has ex-
tensive experience in the field of seal technology and is familiar
with the subject matter of the instant application and the
cited reference.
Mr. Jackson swears, in his professional opinion, that the seal-
ing effectiveness of the Boyce et al seal depends upon compress-
ive loading of the seal which is transmitted to the auxiliary
ring thereof. The sealing effected by applicant's seal, on
the other hand, occurs by virtue of compressive loading of the
disk-like portions which is transmitted through the plastically
deformable hinge portion of the seal.
Thus, in rebuttal of the Examiner's contention that applicant's
structure is obvious in view of the structure of the seal of
Boyce et al, a person who is skilled in the art has sworn that
the sealing effectiveness of the two seals and the transmittal
of the loading of the seal is completely different in applicant's
seal vis-…-vis that of Boyce et al.
In other words, the disk-like flanges of the seal of the present
invention are shaped to act more like a Belleville spring wherein
the metal seal has two resilient thick disks which act "springy"
under compression and a thin cylinder "hooking" or joining the
disks together which, under compression, is "squashed".
The Boyce patent relates to high pressure joints for vessels used in the
synthetic ammonia industry. In his joint the sealing engagement is effected
by a ring placed between the seating surfaces of the parts to be joined.
The ring is in cross sectional form a "V" or "U", with the leg portions
contacting the seating surfaces to form a seal. In order to prevent dis-
tortion of the ring beyond its elastic limit, thus causing it to rupture,
an auxiliary ring may be inserted between the two walls to keep them apart.
Claim 1 in the patent reads:
A joint for resisting high pressure, in which the sealing
engagement is effected at opposite outer surfaces of a
hard metal cup ring, as hereinbefore defined, the internal
surfaces of which are exposed to the high pressure, the
said outer surfaces being convex to the corresponding seating
surfaces of the parts to be joined.
This application is for a seal composed of an annular body of resilient
metal having upper and lower disc-like members joined together by hinge
member. A cross-sectional view is in the form of a "C" or "U" shape in
which the thickness of the hinge is less than the thickness of the leg
members. It is used under high temperature and pressure conditions where
there is substantial thermal expansion and contraction of the constituent
parts. According to the disclosure, the hinge portion undergoes substantial
plastic deflection in use, while the disc portions undergo elastic
deflection. Claim 1 reads:
A metal seal characterized by an annular body of resilient
metal having upper and lower disk-like portions joined by
an integral hinge portion, the ratio of the thickness of the
hinge portion to that of either of the disk-like portions
being such that said hinge portion is capable of substantial
plastic deflection and said disk-like portions are capable
of elastic deflection.
The question the Board must consider is whether the application is directed to
a patentable advance in the art over the teaching of the cited reference.
At the hearing the applicant illustrated what he meant by "plastic" and
"elastic" with a bobby pin. The legs of the pin are analagous to the cross
sectional portions of the seal which are subject to "elastic" deflection,
while the joining or hinge portion undergoes "plastic" deflection. Prior
art seals of this type embodied a very thick cross-sectional hinge portion
when compared to the leg portion, with the result that these seals were not
suitable for the high temperature and high pressure cycling conditions encountered
in industry today.
In the Boyce seal the disc members are joined by an integral hinge member
where the disc portions are also substantially thicker than the hinge. His
patent is for a high pressure joint in which the convex leg portions of
the seal contact corresponding seating surfaces of the parts to be joined.
In order to safeguard against distortion of the disc members beyond the
elastic limit Boyce suggests it is preferable that an auxiliary separation
ring bridge the cup walls to prevent their collapse under compressive load.
This ring is illustrated in all the embodiments shown in the drawings.
In his disclosure Boyce states that:
In the joint of the present invention, however, the sealing
contact is made over a narrow band and the effective sealing
force is thereby magnified and the joint enabled to accommo-
date greater variations of internal pressure without failing,
while at the same time the seating surfaces and the surfaces
of the cup ring do not need to be machined to such accurate
limits as in the said previously proposed joint.
Boyce is concerned with the presence of a convex contact surface to form
the sealing surface, and this is the feature he has emphasized in his patent.
While it is true that Boyce recognized the elastic limit of the discs, and
uses an auxiliary separation ring to prevent distortion, there is no refer-
ence to using "plastic" and "elastic" deflection in his seal, such as is
envisaged by the applicant.
To obtain the "elastic" and "plastic" deflection in his seal the applicant
uses a metal having "resilient, spring characteristics such as a metal alloy
marketed under the trade mark Inconel 718." Boyce states on page 2, line 58
that his material is a "steel cup ring of V-shaped section and an auxiliary
steel ring bridges its walls". Further, at line 84, he adds that
"pressure within the vessel will result in the walls of the ring 4 being
forced outwardly against the faces 1 and 2, thus tightening the joint, the
ring of course being made sufficiently flexible for this purpose." The
use of a steel cup ring as well as a steel auxiliary ring in Boyce shows
that he was concerned with a tight seat engagement between the convex sides
of the ring and the corresponding faces to be joined. This was attained
by tightening bolts to draw the parts together and a vent in the ring to
permit the pressure within the vessel to act on the seal walls, thus in-
creasing the sealing force.
Since Boyce used an auxiliary steel ring to prevent elastic deformation, his
disclosure would not in our opinion lead a person skilled in the art to construct
a seal possessing elastic and plastic deformation. By using a seal whose
hinge is capable of plastic deflection, the applicant is able to "custom
fit" to allowable valve manufacturing tolerances so that his sealing
ring functions satisfactorily under extreme conditions. The utilization of both
plastic and elastic deformation is not taught in the prior art.
In the Final Action it was stated that mere deletion of an element with its
corresponding function (in this case the auxiliary ring 7 which prevents
plastic deformation of the seal ring) is not a patentable step. We agree
that it may be often obvious to omit one or more parts of a machine or manu-
facture with a corresponding omission of function, but here that omission
results in a new mode of operation of the parts retained, with unexpected
advantages. In this invention deletion of the separation ring permits elastic
deformation of the discs to give a better seal than is possible with the
separation ring present. Consequently this constitutes a new mode of operation
of the parts retained. In Hosiers Ltd. v Penmans Ltd. 1925 Ex. C.R. 93 at 102 it
was stated that:
If a process exists which consists of different steps created
by machinery, and there is an improvement in that process caused
by a new element added to or taken from the machinery, then,
the process existing and being known, the party who added to or
took away the part of the machinery might if it were useful, be
entitled to a patent, not for the process which formerly existed
and was well known, but only only for that which had been added
to or taken from the mechanism.
Boyce stresses that the sealing engagement is effected by the outer ring
surface which is convex with respect to the corresponding seating surfaces to
be joined. According to his disclosure previous joints required contact over
the whole area of the sides of the ring which meant that both ring surface
and seating surfaces had to be machined to accurate limits. The applicants
seal has a hinge having deformation characteristics integral with flexible
disc portions which combine to compensate for manufacturing tolerances of the
surfaces to be sealed without requiring a concave ring surface or any machining
of the parts.
In these circumstances, the Board is satisfied that claims 1 to 6 repre-
sent a patentable advance in the art.
The Board recommends that the Final Action refusing the application be with-
drawn.
G.Asher
Chairman
Patent Appeal Board
I concur with the findings of the Patent Appeal Board and withdraw the
Final Action. The application is returned to the examiner for resumption
of prosecution.
J.A. Brown
Acting Commissioner of Patents
Dated at Hull, Quebec,
this 17th. day of November,
1975
Agent for Applicant:
McFadden, Fincham & Co.,
1255 University St.,
Montreal 110, P. Q.