Tube fitting assembly with deformable seal

A tube fitting assembly is disclosed wherein a ductile metal tube is forced into first and second orifices within a fitting. The tube is closely received within the first orifice and the second orifice is larger so that the axial force on the tube axially contracts the tube to form a radially expanded bead on the tube substantially filling the second orifice. This establishes a fluid tight seal between the tube and the fitting and also retains the tube in the fitting. An annular deformable seal member is also provided between an outer surface of the tube and an inner surface of the fitting and this seal may be a rubber-like O-ring or a composition material which is more yieldable than the material of the tube and fitting, may be set up from a liquid or plastic sealant material, or may be a deformable wall of the fitting. The force used to axially contract and radially expand portions of the tube is also utilized to compress the deformable seal between an outer surface of the tube and an inner surface of the fitting to make doubly sure of a good fluid-tight seal. The tube fitting assembly is thus able to withstand higher pressures, suddenly applied pressures, corrosive fluids, and extreme and rapid changes in temperature, with only a negligible number of failures of the assemblies. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.

BACKGROUND OF THE INVENTION 
Tube fitting assemblies have been made in many different varieties and for 
many different uses. When corrosive fluids are to be conveyed by the tube 
and where high pressures are to be utilized, the prior art has generally 
used rather expensive tube fitting assemblies, constructed of expensive 
materials and with rather complex structures taking considerable time to 
manufacture the fitting as well as to assemble it. 
One example of an adverse environment is the use of air conditioning 
assemblies in automobiles. The refrigerant used in the air conditioning 
units is rather corrosive and over a period of time has seemed to attack 
almost all packing or sealing material in the tube fitting assemblies, 
thus eventually causing leaks. Additionally the temperature range within 
the engine compartment of a modern automobile is as much as 200 degrees, 
from below zero degrees Fahrenheit to near 200 degrees Fahrenheit. Still 
further there is considerable vibration both from the engine and from road 
shocks. The combination of these factors has caused the use in automotive 
air conditioners of tube fitting assemblies which are rather expensive to 
manufacture and to assemble, in man hours of labor. Additionally there are 
millions of such automotive air conditioners made each year with many 
joints to be made for each air conditioner, and thus the industry is quite 
anxious to obtain a tube fitting assembly which is not only economical to 
use and manufacture, but also reliable so that expensive warranty work is 
not needed. Retrofitting a defective joint in an existing automobile out 
in the field is far more expensive than the total cost of all fittings on 
the entire automotive air conditioner in the first instance. Hence such 
industry is not interested in a cheap fitting which does not hold up under 
the severe conditions encountered. 
The industry would also like to use aluminum tubing because it is light 
weight yet strong, but aluminum has traditionally been a difficult metal 
to join with another structure, one reason being that it is initially 
ductile but becomes rapidly work hardened and another reason is that the 
aluminum is subject to corrosion in the form of aluminum oxide which is a 
powdery yet an insulating material. 
The prior art has known tube fittings with a flange or an annular bead, 
including those fittings where such bead acted against a resilient packing 
member. However, most of these were with reusable fittings of the two 
piece type such as an interthreaded nut and fitting connection. These are 
expensive to manufacture and time consuming to assemble. Where it is not 
necessary to be able to disassemble the fitting and reuse it, the prior 
art has known fittings which are assembled by an internal mandrel 
expanding the tube against a wall of the fitting. In this case the 
outwardly swaged tube is moved into engagement with a previously prepared 
aperture in the fitting which aperture takes several steps to prepare its 
shape properly to receive the tube. Then a further three or four step 
process is required to use a mandrel and die to outwardly swage the tube 
and finish the process of connecting the tube to the fitting. Accordingly 
the problem to be solved is how to construct a tube and fitting assembly 
and the method of assembling the same so as to overcome the economic and 
practical disadvantages of the prior art. 
SUMMARY OF THE INVENTION 
The problem is solved by utilizing a tube fitting assembly comprising in 
combination: a fitting having a first wall defining a first orifice 
through at least a portion of said fitting, said fitting having a second 
wall defining a second orifice substantially coaxial with and extending 
along at least a portion of said first orifice, said second orifice having 
a greater cross-sectional area than said first orifice, a tube having an 
inner and an outer tube wall with a first portion of said outer tube wall 
having an outer cross-sectional area substantially equal to said first 
orifice and being disposed in said first orifice, retention means 
longitudinally retaining said tube within said fitting and including a 
second portion of said tube longitudinally compressed to have two annular 
parts of said inner tube wall in mutual engagement to establish a radially 
expanded bead portion of the outer tube wall acting against and being 
radially restrained by said second wall of said fitting, and an annular 
deformable seal member in sealing engagement between an outer surface of 
said tube and an inner surface of said fitting. 
An object of the invention is to provide a tube fitting assembly which is 
economical both to manufacture and to assemble and yet will seal high 
fluid pressures. 
Another object of the invention is to provide a tube fitting assembly which 
may be used with many different materials and with various tolerances on 
the structural parts yet which will seal high fluid pressures. 
Another object of the invention is to provide a tube fitting assembly which 
will maintain its sealing integrity despite wide variations in 
temperature, vibration and pressure. 
Another object of the invention is to provide a method of assembly of a 
tube fitting wherein the tube and fitting may be assembled in an extremely 
simple manner yet the assembly will seal high fluid pressures. 
Other objects and fuller understanding of the invention may be had by 
referring to the following description and claims, taken in conjunction 
with the accompanying drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The invention is directed to a tube fitting assembly where a tube and 
fitting are joined so that they are capable of sealing high pressures and 
withstanding considerable mechanical shock and temperature shock. The tube 
is very simply prepared, the preparation consisting merely of providing a 
generally squared end on the tube. The fitting is also easily prepared 
using a stepped drill to form first and second orifices with the second 
orifice generally being a counterbore. Where quite high pressures are 
desired to be sealed an O-ring groove may be formed in the fitting 
requiring an additional step to form such a groove. Next a deformable 
annular seal member is placed in the fitting or on the tube, adjacent a 
longitudinal shoulder in the fitting, the fitting and the tube are 
individually held and then moved together axially along the tube axis. 
This forces the tube into the fitting and after the end of the tube 
strikes a shoulder the tube is longitudinally contracted to form one or 
more annular beads on the tube which are radially expanded. These beads 
are expanded outwardly into enlarged orifices and the longitudinal 
contraction of the tube is continued until two annular parts of the inner 
tube wall are compressed into mutual engagement. This establishes at this 
area of the tube the radially expanded bead portion which acts against the 
enlarged second orifice of the fitting. The fitting radially restrains 
this enlarged annular bead and acts as the means to retain the tube 
longitudinally within the fitting. Where the bead is trapped within a 
groove, this adds further to the longitudinal retention of the tube in the 
fitting despite high pressures. 
The annular deformable seal member initially may be a solid member, a solid 
yet compressible material, a liquid or plastic thermosetting material, or 
any gasketing material, such as an O-ring or Teflon washer. It is forced 
into sealing engagement between an outer surface of the tube and an inner 
surface of the fitting. The seal member is compressed so that a fluid 
tight seal remains despite minute changes in the position of the tube 
relative to the fitting due to temperature changes, mechanical shock or 
vibration, pressure or other changes. 
In FIG. 1, an assembly 15 includes a fitting 16 and a tube 17. The fitting 
may be of various kinds and one is shown having a body 18 and a mole 
thread 19 for connection to a utilization device. The fitting 16 has an 
aperture 20 to convey the fluid of the assembly 15, and has first and 
second walls 21 and 22 defining first and second orifices 23 and 24, 
respectively. The first orifice 23 extends through at least a portion of 
the fitting 16 and communicates with the aperture 20. The second orifice 
24 has a greater cross-sectional area than the first orifice 23 and 
extends along a portion of the first orifice 23. In the embodiment shown 
in FIG. 1 this second orifice is coaxial with orifice 23, and is formed by 
the second wall 22 which is generally cylindrical, by an outwardly facing 
shoulder 25 and by an inwardly facing shoulder 26. 
An annular deformable seal member 28 is provided in the fitting 16, and it 
may be a resilient or semi-solid seal member set up from a settable liquid 
or plastic sealant. Sealants suitable are thermosetting materials such as 
epoxy cements, and anerobic materials which set in the absence of air. In 
this embodiment of FIG. 1 this seal member is a resilient O-ring contained 
in an O-ring groove 29 having a generally cylindrical wall 30 and 
outwardly and inwardly facing shoulders 31 and 32, respectively. 
The tube 17 has an axis 35 generally coaxial with the axis of the fitting 
16. The tube also has an inner and outer tube wall 36 and 37, 
respectively. Initially the tube 17 has an outside diameter of the outer 
wall 37 which is slightly less than the diameter of the first orifice 23 
so that the tube will readily slide longitudinally into this first orifice 
23. 
As assembled, the complete assembly 15 includes retention means 39 to 
longitudinally retain the tube 17 within the fitting 16. A first portion 
38 of the tube 17 is positioned within the first orifice 23. A second 
portion 40 of the tube is longitudinally compressed to have two annular 
parts 41 and 42 of the inner tube wall 36 in mutual engagement. These are 
established by longitudinal compression of the tube 17 and establish a 
radially expanded bead which is the second portion 40 of the tube 17. This 
radially expanded bead acts against and is radially restrained by the 
second wall 22 of the fitting 16. It need not bear directly against this 
second wall 22, so long as the radial outward force of the bead 40 is 
restrained by a concomitant radial inward force from the second wall 22. 
This makes a tight engagement between the bead 40 and the second wall 22 
which acts as a part of the retention means 39. 
The longitudinal compression of the tube 17 also forms a second annular 
bead 45 which expands radially outwardly to radially compress the annular 
resilient seal member 28. Where the seal member is formed from a settable 
liquid or plastic, the material may be applied to the outer surface of the 
tube and then be forced by radial expansion of the tube end to be disposed 
primarily in the groove 29. This seal member may be an O-ring for example 
of fluorocarbon, polyacrylate, or butyl material, as examples. The 
considerable radially outward force developed by the second annular bead 
45 considerably distorts the seal member or O-ring 28 into a generally 
rectangular cross section, except for perhaps some small fillets at the 
corners. 
FIGS. 10-14 show the sequence of events of producing the tube fitting 
assembly 15. The fitting 16 is shown in FIG. 10 wherein a stepped drill 47 
has first, second and third dimensions to drill the first aperture 20, the 
first wall 21 and a third wall 48 next to an outside surface 49 of the 
fitting 16. Next FIG. 11 shows the use of an O-ring grooving tool. This 
tool 50 has a shank 51 which is closely received within the first wall 21 
and has one or more radially outwardly movable cutting tools 52 to move 
outwardly to cut the O-ring groove 29. The mechanism by which these tools 
are moved outwardly is not shown but such tools are commercially 
available. 
FIG. 12 shows the use of another such O-ring grooving tool 54 which enters 
the first orifice 23 and has cutting tools 55 at a different axial depth 
from the end to cut the second orifice 24. These steps will prepare the 
fitting 16 except for whatever secondary operations are required such as 
preparing the threads 19, as required. Next the fitting 16 is held in some 
suitable form of fitting holder 58, shown in FIG. 13. This may be a two 
part vise or it may be a one piece fixture as shown having a longitudinal 
shoulder 59 to resist longitudinal force. The tube 17 is held in a tube 
holder 60 and this is usually some form of a two piece vise or clamp 
having semicylindrical recesses to securely grip the tube to move it 
longitudinally forwardly relative to the fitting 16. The fitting 16 of 
FIG. 13 is shown with the O-ring 28 in place in the O-ring groove 29. 
The end of the tube 17 extends beyond the tube holder 60 by a predetermined 
amount which amount is determined mostly by trial and error. After the 
correct amount is established then in production the amount of this tube 
extension beyond the tube holder 60 is usually provided quickly and easily 
by a fixture or gauge assembly. 
The FIG. 14 shows an enlarged view of the tube 17 partially longitudinally 
compressed into the fitting 16. The initially squared end 61 of the tube 
17 has moved in until it has struck the conical shoulder 62 between the 
aperture 20 and the first wall 21. The continued application of 
longitudinal force has deformed a part 63 of the end of the tube 17 so 
that it is also conical by cold working of the end of the tube. The 
continued longitudinal contraction of the tube 17 enlarges it slightly at 
64 and 65 to fit tightly against the first wall 21 which forms the first 
orifice 23. This squeezes out most of the liquid sealant, if such is used. 
The continued longitudinal contraction of the tube 17 causes it to bulge 
radially outwardly at two different places, the annular bead 45 and a 
partially formed annular bead 40A. The longitudinal contraction of the 
tube 17 forces the metal to cold work and to flow generally radially 
outwardly. Where the outer tube wall 37 is physically restrained as at the 
first wall 21, the expansion of the wall as at 64 and 65 continues until 
it is restrained by this wall. This may be an expansion of only a few 
thousandths of an inch, depending upon the initial tolerance in the slip 
fit between the parts. Where the outer tube wall 37 is not restrained, as 
at the O-ring groove 29 and at the second orifice 24, then the radially 
outward annular bead 45 or 40A is formed. 
The radial extent of the second annular bead 45 is subject to many 
different factors, including diameter of the tube relative to the tube 
wall thickness, ductility of the metal of the tube, relative 
compressibility of the O-ring 28 or trapped liquid sealant, and perhaps 
most importantly the formation of the shoulder 66 at the annular bead 40A. 
When this shoulder 66 digs into the exterior corner 67, formed by the 
junction of the first wall 21 and the shoulder 25, then this is probably 
most effective in preventing further longitudinal movement to the left as 
viewed in FIG. 14 of that forward end of the tubing 17. Thus this tends to 
limit the amount of outward bulging of the second annular bead 45. The 
O-ring 28 may have different durometers which will also help determine how 
much this O-ring will be deformed to fill the generally rectangular O-ring 
groove 29. It may completely fill all corners or there may be small air 
space fillets remaining in the corners. Regardless, there is a good seal 
established between the second annular bead 45 and the O-ring or annular 
seal member 28. 
Upon continued longitudinal contraction of the tube 17, then primarily only 
the second annular bead 40A compresses to form the bead 40 as shown in 
FIG. 1. This longitudinal contraction continues from the position of FIG. 
14 to the position of FIG. 1 until the first part 41 and the second part 
42 of the inner tube wall 36 are in tight engagement with each other. The 
tube holder 60 in this preferred embodiment has an annular cylindrical 
extension 69 which has a small enough outer diameter to just enter the 
third wall 48. This cylindrical extension 69 acts to securely pack the 
annular bead 40 into the second orifice 24. The outer end of the extension 
69 forms an outer wall 70 on the second annular bead 40, as viewed in FIG. 
1. Depending upon the precise position at which the tube holder 60 grips 
the tube 17, this outer wall 70 may be flush with the inwardly facing 
shoulder 26, it may be slightly outwardly of it as shown in FIG. 1, or 
could even be slightly inwardly of it. The important function of the 
extension 69 is that the metal of the tube wall is cold worked to be 
securely packed inside the second orifice 24 so that it acts radially 
outwardly against the second wall 22, and is radially restrained by such 
second wall. This may be a metal-to-metal seal engagement as in my prior 
application Ser. No. 527,683, or may have liquid sealant therebetween if 
such sealant has previously been applied to the tube or fitting in order 
to form the annular seal member 28. This radial restraint by the second 
wall is the retention means 39 which retains the tube 17 in the fitting 
16. In the embodiment of FIG. 1 this retention means is greatly aided by 
the inwardly facing shoulder 26 which securely locks the annular bead 40 
within this fitting 16. 
As the extension 69 rams the material of the annular bead 40 within the 
second orifice 24, if there is a slight excess of material, then this 
sometimes causes the inside diameter of the tube 17 to be slightly 
restricted or bulged inwardly as at 71, although this is normally only a 
few thousandths of an inch and also normally occurs only with the smaller 
tubing diameters such as one-eighth and three-sixteenths inch OD sizes. 
Further the junction line 72, shown in FIG. 1, between the first and 
second engaging parts 41 and 42, may or may not be visible. In cutting 
into two longitudinal half sections a complete tube and fitting assembly 
15, if the tube 17 is clean and uncorroded, usually this junction line 72 
is not visible. It would be visible if the tube had first been painted 
black on the inside, if the inner tube wall is corroded, or if the 
assembly 15 is etched with acid after sectioning. However, usually with 
the unaided eye such junction line 72 is not visible. 
The preferred dimensions of the various apertures in the fitting 16 depend 
upon the specific use, type of material of tube and fitting, tube diameter 
and tube wall thickness. The first wall 21 has a bore diameter just a few 
thousandths larger than the outside diameter 37 of the tube 17. Industry 
standards permit 0.004 inches tolerance in the outer diameter of the tube, 
so usually the diameter of the bore wall 21 is 4 to 6 thousandths larger 
than the tube diameter. The diameter of the second wall 22 has a 
theoretical size of the outside diameter of the tube plus twice the tube 
wall thickness. The axial length of this groove or second wall 22 is about 
one and one-half times the tube wall thickness. The axial depth of the 
first wall 21 plus second wall 22, namely, how far the tube is inserted 
into the fitting 16, is a minimum of the tube outside diameter plus twice 
the tube wall thickness. Inserting the tube 17 further into the fitting 16 
by a deeper bore generally produces a stronger tube fitting assembly. The 
diameter of the orifice 20 is most anything suitable to carry the fluid 
flow but the maximum is about the inside diameter of the tube 17 in order 
to prevent extrusion of the tube 17 into this orfice 20. 
The fitting has been successfully used on copper, steel and aluminum tube 
and fitting materials. The following table A shows typical dimensions 
which have been used satisfactorily for aluminum tubing used in aluminum 
fittings. 
TABLE A 
______________________________________ 
Tube O.D. .125" .188" .250" .375" 
I.D. of orifice 23 
.127/.131 .187/.191 
.252/.256 
.377/.381 
I.D. of orifice 24 
.173 .250 .313 .500 
axial length of 24 
.035 .050 .050 .050 
axial length of 
.198 .200 .334 .325 
23 + 24 
I.D. of orifice 20 
.094 .062 .125 .230 
______________________________________ 
FIG. 2 shows a further tube and fitting assembly 75 according to a further 
embodiment of the invention. This assembly 75 includes a fitting 76 which 
is different from fitting 16 of FIG. 1 and illustrates the many different 
forms of fittings with which the invention may be used. The fitting 76 may 
be an example of something like a manifold block into which many different 
tubes 17 are assembled, and extend completely through such fitting 76 to 
leave an exposed end 77 of the tube 77. Some utilization device is 
connected to the exposed end 77 and sealed thereto by a second O-ring 78 
disposed in a counterbore 79. The retention means 39 is essentially the 
same as in FIG. 1 and includes the annular bead 40 acting against and 
being radially restrained by the wall of the second orifice 24. An annular 
seal member 81 is used and is disposed between an outer surface of the 
tube 17 and an inner surface of the fitting 76. This annular seal member 
81 is not circular in cross section initially, as is the O-ring 28, it is 
preferably a flat washer shaped member. Teflon is one suitable substance 
for this annular seal member 81. Teflon is not as resilient as butyl, 
fluorocarbon, or polyacrylate, the suggested materials for the O-ring, but 
is more resilient or deformable than the metal of the fitting 76 and tube 
17. 
In the formation of the tube fitting assembly 75 of FIG. 2, the end of the 
tube 77 needs to be held as well as the fitting 76, in order to have a 
force resisting the inward movement of the tube 17 by the tube holder 60. 
Since there is no shoulder in the fitting 76 to resist this force, this is 
supplied by some external anvil, for example. This might be a part of the 
fitting holder 58 of FIG. 13, as an example. The tube 17 is longitudinally 
compressed as before to form the annular bead 40 and this longitudinally 
compresses the annular seal member 81 between the shoulder 25 of the 
second orifice 24 and an inwardly facing shoulder wall 82 on the annular 
bead 40. The axial depth of the second orifice 24 may be increased 
slightly to accommodate the axial thickness of the annular seal member 81. 
FIG. 3 is a longitudinal sectional view of another tube fitting assembly 85 
constructed in accordance with the invention. This assembly includes a 
fitting 86 which has an orifice 87 communicating with the first orifice 
23. In this embodiment the orifice 87 is not coaxial with the orifice 23 
as in FIGS. 1 and 2 but is transverse thereto to illustrate the 
flexibility of applications of the invention. The retention means 39 may 
be the same as in FIG. 1. An annular deformable seal member 89 is disposed 
in an axial recess between a flat shoulder 90 at the inner end of the bore 
forming the first orifice 23 and the flat end of the tube 17. A radial 
shoulder 91 also defines part of the axial recess and helps contain the 
seal member 89, especially if it is formed from a settable liquid sealant. 
The constructions of FIGS. 2 and 3 are slightly simpler than that of FIG. 1 
because the O-ring groove 29 is omitted hence the step of FIG. 11 may be 
omitted. All of the embodiments of FIGS. 1, 2 and 3 have the inwardly 
facing shoulder 26 which may be formed in a variety of ways, for example 
by a threading operation, but as shown is formed by the O-ring grooving 
tool 54. 
FIG. 4 shows another tube fitting assembly 95. This assembly shows a 
fitting 96 which is similar to the fitting 16 of FIG. 1 in that it has the 
male threads 19 and the O-ring groove 29 with the O-ring 28. One 
difference however is that the second orifice 97 has the second wall 98 
thereof extending completely to the outside surface 49 of the fitting 96. 
The retention means 99 is quite similar to the retention means 39 of FIG. 1 
except that it does not rely upon any inwardly facing shoulder on the 
fitting 96. This retention means relies on the radially outward force of 
the annular bead 40 acting against and being restrained by the cylindrical 
wall 98 of the second orifice 97. 
FIG. 5 shows an additional modification of the invention with an assembly 
105 employing a fitting 106. Only part of this fitting 106 is shown and it 
has an orifice 107 communicating with the first orifice 23 into which the 
tube 17 is received. Retention means 109 is disposed in the second orifice 
97 as in FIG. 4 which orifice extends to the outside surface 49 of the 
fitting. An annular seal member 110 in the form of a deformable flat 
washer is provided. After longitudinal compression of the tube 17, this 
annular seal member makes sealing engagement between the outwardly facing 
shoulder 111, which forms part of the second orifice 97, and the inwardly 
facing shoulder 82 on the annular bead 40 which forms a part of the 
retention means 109. As shown in FIG. 5 there may or may not be a slight 
exterior flash 112 on the annular bead 40 overlying the outer surface 49 
of any of the fittings in the drawing, such as the fitting 106. This 
exterior flash may be caused if there is a slight excess of material being 
longitudinally compressed to form this annular bead 40. The presence of 
such annular flash is not harmful, and its presence merely serves to 
signify that the cavity or second orifice has been completely filled by 
the annular bead 40. 
FIG. 6 shows another tube fitting assembly 115 which is shown with a 
fitting 116 having the aperture 20 communicating with the first orifice 23 
which initially closely receives the tube 17. 
The fitting 116 is prepared differently from that of FIG. 5 by using a 
special stepped drill which will form not only the first wall 21, but a 
third wall 118, an outwardly facing shoulder 120 and an extension wall 121 
of the first wall 21 which extends into the second orifice 123. This 
extension wall, as formed, is cylindrical for easy formation with the 
first wall 21, and is about one-third the length of the second orifice 
123. After the tube has been longitudinally forced into the first and 
second orifices 23 and 123, respectively, the annular bead 40A is formed 
as before by the folding together of annular inner portions of the tube 
wall. The large force established by this annular bead 40A acts radially 
outwardly as before to establish the retention means 119 by acting 
outwardly against the third wall 118. This longitudinal compression of the 
tube and formation of the annular bead 40A also causes it to exert a force 
inwardly on the extension wall 121. This force has a component of force 
which acts radially inwardly all the way around this annular extension 
wall 121 and forces it inwardly. In fittings made in accordance with this 
invention, the extension wall is deformed inwardly at about a 20 degree 
angle and the curve of deformation starts at a line 122 which lies inboard 
of the plane of the outwardly facing shoulder 120. This deformed extension 
wall then establishes a complementary groove 124 in the outer wall of the 
tube 17. The extension wall 121 thus bites into the tube outer wall to 
form not only a good metal-to-metal seal, but also acts as a part of the 
retention means 120 to longitudinally retain the tube 17 within the 
fitting 116. A liquid sealant may also be used with this construction of 
FIG. 6 in which case there may not be a metal-to-metal contact between the 
enlarged bead 40A and the third wall 118, the bead may be restrained by 
the third wall with the intermediary of the sealant acting as the annular 
resilient seal. 
FIG. 7 shows a further tube fitting assembly 125 according to the invention 
which utilizes a fitting 126. This fitting is provided with the O-ring 
groove 29 and O-ring 28. Retention means 129 is provided in a second 
orifice 128. This orifice 128 is provided by a cylindrical wall 130 and a 
slightly conical wall 131 which establishes a sharp junction 132 where it 
joins the wall 21 of the first orifice 23. The annular bead 133 which 
fills this second orifice 128 is similar to the annular bead 40 except 
that the tube wall, in being folded double, has been forced to have a 
conical wall to conform to the conical wall 131. Additionally, an 
effective fluid tight seal is made at the line between the sharp junction 
132 and the annular bead 133. 
FIG. 8 shows another tube fitting assembly 135 which includes a fitting 
136. This fitting has the O-ring groove 29 and the O-ring 28 and has a 
retention means 139 similar to that of FIG. 1 in that it includes the 
inwardly facing shoulder 26 of the second orifice 24. Additionally, this 
retention means 139 includes a reinforcing ferrule 137, for example, made 
of steel, which has a flange 138 engaging the annular bead 40. An inturned 
annular lip 140 is formed by cold working the fitting such as by staking. 
This inturned lip bears against the outer surface of the flange 138 to 
help retain it in place and at the same time help retain the entire tube 
17 inside the fitting 136. The staking, as caused for example by an 
annular bead 141, may be performed as a separate staking operation, but 
preferably is formed at the same time as the conclusion of the forming of 
the assembly 135 by having this annular bead 141 on the front edge of the 
tube holder 142 to strike and deform the outer surface 49 of the fitting 
136. The tube holder 142 may have a shoulder 143 to locate the ferrule 
137. 
FIG. 9 shows another tube fitting assembly 145 incorporated in a fitting 
146. In this case the O-ring is omitted and an annular deformable seal 
member 147 is provided, which may be a flat annular member, or one set up 
from a liquid sealant. This seal member 147 is disposed between a flat 
shoulder 148 and the squared end 150 of the tube 17. Retention means 149 
utilizes the annular bead 40 which acts radially outwardly against the 
second wall 22 of the second orifice 24. A third wall 151 of this second 
orifice is formed later by cold working, for example, by staking. This 
third wall 151 is an inwardly facing shoulder and may be formed by the 
bead 141 on the tube holder 152. This inwardly facing wall 151, formed by 
staking, may also be used in the method of making the fitting 15 of FIG. 1 
just subsequent to the drilling step of FIG. 10. 
Each of the tube fitting assemblies disclosed provides a unique seal 
arrangement to assure a fluid-tight seal. The construction of FIG. 1, for 
example, has survived rigorous tests. The assembly will withstand 2000 psi 
fluid pressure and will also withstand vibration testing and severe 
temperature change tests. One such test passed by this tube fitting 
assembly is to have the tube and fitting assembly immersed in a liquid at 
-359.degree. F. and then suddenly plunged into heated oil at 212.degree. 
F., then another 1000 cycles of vibration. As disclosed in my parent 
application Ser. No. 425,561 the annular bead 40 makes a good fluid tight 
seal with the inwardly facing wall of the fitting. The deformable annular 
seal provided by the settable liquid sealant, the O-ring 28, the various 
flat annular seal members, or the deformed extension wall 121, makes 
doubly sure that the fluid-tight seal will remain despite severe changes 
in temperature, pressure or vibration. 
In refrigerant applications, for example, the refrigerant is rather 
corrosive, especially over a period of time and where high temperatures 
are encountered. This combination of corrosive fluid, high temperatures 
and vibrations is encountered in automotive air conditioning units, for 
example, and because of the great volume of these units being produced 
each year, it is desired to utilize an economical fitting. The present 
invention does disclose such a tube fitting assembly which is economical 
to manufacture and to assemble and yet one which assures an absolute 
minimum of leakage failures. Assembly line personnel often get bored with 
their jobs and may tend to get a little sloppy in performing their 
assigned tasks. The present tube fitting assembly is one which is quite 
forgiving and will accommodate a number of errors in or deviations from 
the preferred assembly method. 
In my parent application the metal-to-metal seal provided by the annular 
radially expanded bead was often used to seal only about 2 psi in gas 
pilot light assembly for gas ranges. Such assemblies operating at 2 psi 
were tested at 100 psi and would readily meet this test. The present 
invention is designed to be used in more stringent applications, for 
example, where 2000 psi tests are required as well as vibration and severe 
temperature and pressure changes. In many cases it has been found that the 
refrigerant over a few years time gradually deteriorates any O-ring 
material. In such case if the fluid leaks past the resilient seal member, 
it will be stopped by and will not leak past the metal-to-metal seal 
provided at the annular bead 40. 
Alternatively, suppose the vibration or pressure shock or temperature 
change breaks loose the metal-to-metal seal, or perhaps heat anneals the 
metal so that it relaxes slightly, in such case the resilient annular seal 
is still present to provide a fluid-tight seal. Also aluminum is an odd 
material. It is light yet strong so it is desired to be used in automotive 
air conditioning applications. However, in the past, it has often been 
considered difficult to properly join at a tube fitting assembly and 
welded joints were often used. In welding, for example, aluminum will just 
barely start to droop from the heat and then will suddenly melt and run. 
Thus it is difficult to properly weld. Also the aluminum, while it is a 
good conductor, often will acquire an aluminum oxide coating because of 
corrosion and this is a powdery material which is a good insulator. When 
the tube surface does become corroded and it is then tried to be made into 
a tube fitting assembly, problems of establishing a good fluid tight seal 
are compounded. The present invention provides improved results under such 
circumstances. The cold working and bending the metal into a U-shape to 
form the annular bead 40 breaks loose the aluminum oxide on the surface so 
that a good metal-to-metal seal is achieved at the second wall 22. Also 
high torsional strength is achieved from the cold working of the metal to 
form this annular bead 40. This high torsional strength is often needed 
where, at a long distance from the fitting, a torsional force is applied 
to the tube 17. 
The combination of the metal-to-metal seal plus the annular deformable seal 
provides still another advantage. In the prior art form of joints if the 
joint were to fail then one could have a large squirting of liquid out of 
the failed fitting. In the present fitting if one of the two seals fails, 
for example, the metal-to-metal seal, then the O-ring or annular seal 
member will usually hold sufficiently so that there is only a slight 
seepage of liquid rather than a large squirting of liquid. 
FIGS. 10-14 show the assembly method for the assembly of FIG. 1. The 
assembly method for FIGS. 2-9 are generally simpler than that of FIG. 1, 
so those skilled in the art will readily comprehend such methods from the 
above description and the drawing. 
The present disclosure includes that contained in the appended claims, as 
well as that of the foregoing description. Although this invention has 
been described in its preferred form with a certain degree of 
particularlity, it is understood that the present disclosure of the 
preferred form has been made only by way of example and that numerous 
changes in the details of construction and the combination and arrangement 
of parts may be resorted to without departing from the spirit and scope of 
the invention as hereinafter claimed.