Pipe fitting having a non-metallic sealing member

A pipe fitting comprising interconnected threaded male and female members. A fitting element in the form of a non-metallic ring is defined by a tubular body, a radial flange and a sealing portion extending from the radial flange. The tubular body of the ring is adapted to be inserted into the male member such that the radial flange overlies the end wall of the male member. The outer periphery of the sealing portion of the ring has a diameter greater than the minor diameter of the threads of the female member. As a result, a part of the sealing portion is caused to be captured between opposed thread flanks of the male and female members upon make-up of the fitting thus providing for enhanced sealing at the threads of the fitting. In addition, the ring serves to isolate the end wall of the male member from contact with fluid thus making the fitting advantageous in the embodiment in which a non-metallic lining is provided in the male member.

BACKGROUND OF THE INVENTION 
This invention relates to a pipe fitting and, in particular, a pipe fitting 
in which a non-metallic ring is adapted for use with threadedly 
interconnected male and female members. 
When pipe fittings are made up it is sometimes desirable to provide 
sealants or other means at the threads in order to prevent the escape of 
fluid. It has been known, for example, to apply liquid or paste type 
sealant materials to the threads prior to make-up of the fitting. It has 
also been known to provide for the application of fluoroplastic protective 
ribbons at the threaded interface of a pipe fitting for purposes of 
filling the space between adjacent thread flanks. 
This invention relates to a pipe fitting and a non-metallic ring for use in 
conjunction with a pipe fitting and wherein the ring is provided with a 
sealing portion which is adapted to be engaged by interconnecting threads 
of the respective joint members. As a result there is provided enhanced 
sealing at the joint upon make-up. The ring also serves to isolate the end 
wall of one of the members of the pipe joint making it possible to 
advantageously cooperate with a pipe lining thus isolating the member from 
contact with fluid. 
SUMMARY OF THE INVENTION 
Briefly summarized, this invention provides for an improved pipe fitting in 
which a non-metallic sealing member is caused to be disposed between 
opposed flanks of interconnecting threads of the male and female elements 
of the fitting. The sealing member is defined by a sealing lip which is 
carried by the radial flange of a non-metallic annular ring carried by the 
male member of the pipe joint. The ring is provided with a tubular body 
which is inserted into the male member in close contact with the internal 
wall of the male member. The radial flange is caused to overlie the end 
wall of the male member and cooperates with the sealing lip to isolate the 
end wall of the male member from contact with fluid. Where the male member 
is provided with a non-metallic interior lining the ring advantageously 
provides for complete sealing of the end portion of the male member thus 
isolating the male member from contact with fluid.

Turning now to FIG. 1, the pipe fitting of this invention, which is 
generally designated 10, is shown in combination with an anode-outlet 12 
installed in the top wall 14 of a water heater. An internally threaded 
spud 16 is welded to wall 14 and defines internal threads 18 which receive 
external threads 20 of the anode-outlet 12. 
Although the anode-outlet 12 of FIG. 1 forms no part of this invention, a 
brief description of this element is believed to be helpful in 
understanding the contribution made by the invention of this application. 
As shown in FIGS. 1 and 2 the anode-outlet 12 consists of a metallic nipple 
22 having external threads 20, 24 at the respective ends thereof. A 
metallic sleeve 28 is received within nipple 22 and is secured to the 
internal wall thereof by means of the generally inwardly extending annular 
rib or corrugation 30. Although not shown in either FIGS. 1 or 2 the 
sleeve 28 functions to grip and retain the magnesium anode 32 (FIG. 1) 
while providing for an electrical interconnection between the anode 32 and 
the wall 14 of the water heater. A plastic sleeve or lining 34 is provided 
at the interior of the anode-outlet 12 and defines a waterway 36 for the 
flow of hot water from the water heater. An aperture 38 is defined in the 
side wall of the anode-outlet 12 and intersects the waterway 36 in order 
to provide for the introduction of water into the waterway 36. 
As will be apparent from a study of FIG. 2, the non-metallic sleeve or 
lining 34 isolates the metallic sleeve 28 and the nipple 22 from contact 
with fluid thus tending to diminish or reduce altogether corrosion of 
these parts as the anode-outlet 12 is placed in service in a water heater. 
As has previously been noted the anode-outlet 12 as shown in FIGS. 1 and 2 
forms no part of the invention of this application except insofar as the 
pipe fitting of this invention may be used in combination with the 
anode-outlet. For a more complete description of the anode-outlet 
reference is made to U.S. Letters Pat. Nos. 3,542,663 and 3,891,530 which 
are owned by Perfection Corporation of Madison, Ohio, the assignee of this 
application. 
This invention is broadly designated 10 in FIGS. 1 and 2 and provides for a 
pipe fitting between an externally threaded tubular male member and an 
internally threaded female member. In the preferred embodiment of the 
invention as shown in FIG. 2 the externally threaded tubular male member 
is designated as nipple 22 and the internally threaded female member is 
designated as element 40. The connection between nipple 22 and element 40 
is provided primarily by means of interengaging external threads 24 on the 
nipple and internal threads 42 defined by the element 40. 
As will be apparent from FIG. 2, element 40 may be defined by a section of 
pipe or a plumbing element such as a "T", "L" or any other element which 
is convenient or desirable for purposes of conducting the flow of fluid. 
Disposed within the externally threaded tubular male member 22 is a 
generally annular ring 46. Ring 46 (as shown individually in FIGS. 3-5) 
includes a tubular body 48, a radial flange 50 and a thread engaging 
sealing portion or lip 52. 
Tubular body 48 of ring 46 is provided with an internal wall 54 and an 
external wall 56. Internal wall 54 defines a passageway for the flow of 
fluid through the fitting. External wall 56 is adapted to be brought into 
tight fitting engagement with the internal surface of the male member. In 
the preferred embodiment as shown in FIG. 2, the internal surface of the 
male member or nipple 22 is provided with a lining 34. Thus, the dimension 
of the external wall 56 is selected so that the tubular body 48 of ring 46 
is in tight fitting engagement with the lining 34. A tapered surface 58 is 
defined at the inner end of the external wall 56 of tubular body 48 in 
order to facilitate the installation of the ring 46 in the tubular male 
member as shown in FIG. 2. 
At the upper end of the tubular body 48 there is provided a substantially 
generally transversely outwardly extending radial flange 50. As will be 
noted in FIG. 2 the transverse dimension of flange 50 is such that it 
extends over the end wall 60 of lining 34 and, in addition, extends at 
least partially over the end wall 62 of the nipple 22. As is shown in FIG. 
5, radial flange 50 is defined by an inner wall 64 and a generally 
parallel outer wall 66. Inner wall 64 is, in the preferred embodiment, 
brought to bear into close contact with end wall 60 of lining 34 and at 
least a portion of end wall 62 of nipple 22. The engagement of ring 46 
with the respective end walls 60, 62 of the lining and nipple is enhanced 
by the cooperation of the sealing portion 52 and the interengaging threads 
24, 42 as will be explained further below. 
As will be noted from FIGS. 3 and 5 radial flange 50 is generally circular 
in configuration. Depending therefrom is sealing portion or lip 52 which 
extends generally radially outwardly from radial flange 50. 
Sealing portion 52, in the preferred embodiment, is defined in section by a 
lip having a thickness which decreases along a transverse axis of ring 46. 
As will be apparent from FIG. 5, the thickness of the sealing lip 
decreases from a maximum at the radial flange 50 to a minimum at the outer 
edge 68. As will further be appreciated from a study of FIG. 5 outer edge 
68 is substantially coplanar with the inner wall 64 of flange 50. 
The outer periphery of the sealing portion 52 of ring 46 or, stated in 
other words, the outer periphery of the edge 68, has a diameter greater 
than the minor diameter of the threads 42 of element 40. Thus, with the 
ring 46 installed in the position of FIG. 2 there is created an 
interference relationship between the sealing portion 52 of the ring and 
the interengaging threads 42, 24 of members 40, 22. As the element 40 is 
advanced onto the nipple 22 parts of the sealing portion 52 of the ring 
are caused to be captured or trapped between opposed flanks of the 
interengaging threads 42, 24. As a consequence thereof, sealing is 
enhanced at the interengaging threads 42, 24. 
In the preferred embodiment, ring 46 is integrally molded from plastic 
material in the configuration shown in FIGS. 3-5. While polypropylene 
material is used although other materials should be considered within the 
spirit of this invention. Also in the preferred embodiment, the sealing 
portion 52 has a cross-sectional thickness at the edge 68 (as shown in 
FIG. 5) of approximately 1/64 inch in the 3/4 inch pipe size ring. 
Applicant has found that in alternate embodiments it is possible to define 
a sealing lip at the outer periphery of the radial flange of the ring by 
advantageously providing for the formation of flash on the radial flange 
during molding of the ring. 
Generally speaking, in order to insure an interference engagement of the 
sealing portion of the ring with the threads of the pipe joint it is 
necessary to provide that the outer diameter of the sealing lip should 
exceed the minor diameter of the internal threads of the female member. In 
the preferred embodiment, Applicant provides that the diameter of the 
outer extremity or the outer edge 68 of the sealing lip should be 
substantially equal to the average pitch diameter of the pipe thread 42 
defined by element 40. Within the spirit of this invention, however, 
should be considered various alternative dimensions at the sealing portion 
of the ring that would provide for interference engagement of the ring 
with the pipe joint threads. Interference is established when the diameter 
of the outer edge of the sealing ring lies in the range between the minor 
and major diameters of the internal threads of element 40. 
In addition to enhancing sealing at the threaded interface between the male 
and female members of the pipe fitting of this invention, ring 46 serves 
the additional purpose of maintaining the fluid tight integrity of a lined 
tubular male element of the type shown in FIG. 2. 
It was previously noted that the pipe fitting of this invention is 
advantageously used in connection with an anode-outlet 12 of the type 
shown in FIGS. 1 and 2. The lining 34 which is provided at the interior of 
nipple 22 and sleeve 28 is, in the preferred embodiment of FIG. 2, 
fabricated from white polypropylene and serves to define an internal 
waterway 36 while, at the same time, isolating the metallic members 22, 28 
from contact with fluid. Lining 34 thus tends to inhibit corrosion of the 
metallic elements of the anode-outlet. 
It has been found, however, that the upper portion 70 of lining 34 may, in 
some circumstances, pull away from the internal wall 72 of nipple 22 thus 
defining a very slight annular space exposed to fluid. This annular space 
thus serves to introduce fluid to the metallic members defining the 
anode-outlet 12 with resulting corrosion and degradation of these members. 
Applicant's ring 46 advantageously serves as an end shield or sealing means 
which serves to inhibit the flow of fluid into any space that may be 
created between the matallic tubular pipe and the internal plastic lining 
thereof. In the preferred embodiment of FIG. 2 the radial flange 50 and 
sealing portion 52 cooperate to tightly and sealingly engage the end wall 
60 of lining 34 and the end wall 62 of nipple 22 thus to prevent the flow 
of fluid into contact with the metallic nipple 22 or any internal portions 
of the anode-outlet such as the metallic sleeve 28. 
This invention, therefore, has application not only with respect to unlined 
fitting members but also with respect to any type of lined pipe wherein it 
is desirable to insure the maintenance of fluid tight integrity of the end 
portions of the pipe and lining. 
It was previously indicated that the tubular body 48 of ring 46 was closely 
received within the internal wall of lining 34 defining waterway 36. In 
the preferred embodiment the tubular body of the ring is positioned close 
to the wall defining lining 34 such that the flow of fluid between these 
elements is effectively prohibited. 
It will be appreciated that as sealing portion 52 is brought into an 
interference relationship with interengaging threads 42, 24 radial flange 
50 will be biased into close engagement with end walls 60, 62 of the 
respective lining 34 and nipple 22. This movement of the ring during 
take-up of the fitting serves to enhance sealing upon takeup. 
A still further advantage of the invention of this application resides in 
the fact that the sealing ring 46 serves to isolate what may, in some 
cases, be severe localized electrolytic action caused by fluid coming into 
contact with dissimilar metals. For example, should the nipple 22 and 
element 40 be fabricated from dissimilar metals it may be expected that 
advanced corrosion will take place at the threaded interconnection of 
these members in the presence of an electrolytic fluid. Applicant's novel 
sealing ring serves to isolate the interengaging dissimilar metals from 
contact with fluid thus serving to greatly reduce corrosion at the 
interface of these metals. 
Alternate embodiments of Applicant's preferred apparatus should be 
considered within the spirit of the invention. For example, the tubular 
body 48 of ring 46 may be retained in the threaded male member in several 
ways. The ring may be press fitted into the male member or, alternately, 
snapped in place utilizing cooperating elements of both the male member 
and the ring. Also it is contemplated that the ring may be retained in 
place in the male member by solvent welding or other bonding techniques. 
While applicant prefers to mold the sealing ring as a one-piece integral 
unit alternate constructions may be employed. For example, the sealing 
portion of the ring could be fabricated as an independent element which is 
carried by the ring and brought into interference engagement with 
interconnecting threads of the pipe joint.