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‘ > v 10, 1946.
2,412,487 -
Filed Jan. 3, 1-944
' (Pl/‘var B. Am/ey
IJqim 8. Gregory
(- a
64d. .1: U
Patented’ Dec. 10, 1946
umrso stares v.Pirrarrr ornca
Oliver B. Amley, Bay City, and John BrGi'egory,
Midland, Mich., as‘signors to The Dow Chemical
Company, Midland, Micln, a corporation of
‘ Application ‘January 3, 1944, Serial No. 516,766'_
2 Claims. (Cl. 285-137)
This invention relates to plastic ?anges useful
in connecting sections of pipe.
the ?ange at an angle to the plane of the ?rst
section. The outer section of the ?ange face
thus assumes the shape of a portion of the sur
In the assembling of piping systems, for the
transfer of ?uids it is frequently desirable touse
pipe constructed of plastic substances, such as
face of a very. ?at cone.
Reference is made to the accompanying draw
cellulose derivatives, phenol-formaldehyde resins,
ing in which, in the interest of clarity, certain '
and the polymers or copolymers of'vinyl chloride,
features. are shown on a somewhat exaggerated vinylidene chloride, or polystyrene. Pipe con
scale and wherein:
structed of such plastic materials has many ad
Fig. 1 is a plan view of a thermoplastic pipe
vantages for certain purposes in the way of ?ex 10 ?ange embodying one modi?cation of the inven
ibility, resistance to ‘chemical action, and, in vcer
tion, and
tain instances, of attailability over special metals
Fig. 2 is a view, partly in section, along the
or metal alloys required for particular applica
lines 2-? of Fig. 1.
tions. In the assembling of such plastic piping
The pipe ?ange of Figs. 1 and 2 is a. unitary '
systems considerable difficulty has heretofore
thermoplastic molded article, circular in‘nature, '
been experienced in securing tight joints between
and having a central bore II which is, in this
pipe sections with plastic ?ange unions when
instance, threaded to receive a threaded pipe. A
using ?anges constructed from thermoplastic sub
' thickened hub l8 and a wide reinforcing web,
stances and leakage through the union has usually
'or rib, l3, around ‘the hub and extending out
occurred at pressures‘ considerably below the 20 wardly around the bolt holes M are provided to
working pressure of the. pipe. It is thought that
stiffen the ?ange. Referring to Fig. 2, the face
such difficulty is due vto the somewhat ?exible
of the flange consists of a narrow inner portion,
nature of thermoplastic polymers, copolymers, and '
resins and that it is thus not possible to draw
down the ?anges sumciently tight with ?ange 25
the bolts. The disadvantages of using metal
backing rings for thermoplastic ?anges or of re
lying entirely on the stiller but more slowly pro
bolts to secure a tight joint at all points between
duced and more expensive ?anges constructed
from thermosetting substances are equally appar
ent. Attempts have been made to provide leak
proof thermoplastic ?ange unions by using extra
heavy ?anges but these consume undesirably large
amounts of material and even then freedom from
leakage is not always assured.
It is, therefore, an object of the present inven
tion to provide a thermoplastic flange useful in
joining together sections of pipe to produce a,
?uid-tight Joint. '
It is an additional object to providea plastic
they may be drawn together to form a ?uid-tight
These and related objects are accomplished
readily by molding, or otherwise forming, a ?ange
member having a central bore, which may, if
desired, be threaded to receive a threaded pipe,
rial from which the ?ange is- fabricated.
which- recedes outwardly from the bore and
which is inclined in the direction of the body of
Gen- >
erally Speaking, the angle A will be smaller the
40 more rigid or less resilient is the material from
which the ?ange is made, the smaller its outside
diameter and-the smaller theepipe which it is
' designed to receive. If the angle A is too small,‘
e. g. smaller than about 1°, a leak-proof Joint
45 may not be obtained; while, if the angle is larger
than about 5°, the hub of the ?ange may be
pulled away from the threaded portion of the
, pipe when the ?ange union is tightened thus
and having a working fwe, the surface of which 50
consists of a narrow inner section lying immedi
ately around the bore and in a plane perpendicu
lar to the axis of the bore, and an 'outer section
angles to the longitudinal axis of the bore. The _
remaining, or outer, portion l6 of the ?ange face
is inclined at a small angle in the direction of the
body of the ?ange from the perpendicular plane
of the inner portion l5 of the face. The extent
30 of. such inclination-ismeasured by the angle A
and usually amounts to from about 1° to about
5°, and preferably from about 2° to about 4°. The
size of ‘the angle A depends, of course, upon a
number of factors including the size of the pipe
35 which the ?ange is adapted to receive, the out
side diameter and thickness of the ?ange, and in
particular the nature of the thermoplastic mate
?ange union, the ?angemembers of which have
_ working face surfaces of such con?guration that
or land, l5 surrounding and adjacent to the
threaded bore II and lying in a plane at right
permitting leakage through the thread.
The radial width of the land or inner portion
of the ?ange facev lying in a. plane perpendicular
to the axis of the bore may be varied over con
siderable limits and, in general, will be somewhat
greater for stiff, fairly rigid ?anges than for those
having greater resiliency. . Flanges adapted to
. _
'receivestandard size pipe having an internal di
ameter up to about 3 inches and having a land
with a radial width of from about 1/6 to about %
inch, have been made and used with entire
satisfaction. It “is, of course, understood that
lands having a greater or lesser-radial width than
this may be used if desired.
A narrow chamfer
l1 around the larger end of the threaded bore is
tance of about 13.; inch outwardly from the bore.
.in a plane perpendicular to the longitudinal axis
or the bore and thence outwardly to the perimeter
of the ?ange at an angle of about 3° in the direc
tion of the ?ange body with a continuation of ‘the
same plane. The ?ange union was assembled
without a. gasket and the ?ange bolts drawn
down evenly all around until the ?anges were in
useful to facilitate entry of a threaded pipe sec
?rm contact around their outer edges.
and then bolted together in the customary
union occurred at about 500 pounds per square
inch. After continuous subjection of the union
to a working pressure of 400 pounds per square
inch for three weeks no sign of leakage was evi
10. joined sections of pipe were then ?tted with suit
'tion into the bore.
In use, the ?anges are simply screwed onto ' able connections and the assemblage tested with
water under pressure. Leakage through the
threaded :pipe sections which it is desired to join
fashion, the bolts being tightened evenly all
around until the outer edges of the plastic ?anges
are ?rmly in contact. Su?lcient stress is thus
placed upon the lands of the two ?anges to pro
In a comparative test, ?anges were used hav
vide a ?uid-tight seal. Gaskets are not-usually
ing the same dimensions as those just described
‘necessary and are, in fact, often undesirable.
Pipe cement may be used in ?tting the threaded 20 but having ?at ‘faces lying from the bore out
wardly to the perimeter of the ?ange in a plane
pipe section into the ?ange if desired.
perpendicular to the longitudinal axis of the bore.
Thermoplastic ?ange unions which have a
The union leaked at a. pressure of less than 50
leaking pressure considerably higher than the
pounds per square inch.
bursting pressure of pipe made from the same
In a further comparative test, ?anges were used
thermoplastic substance may be made readily ‘ 25
similar .to those with ?at faces just described,
when using the ?ange members of the present in
except that they were molded with a raised land
vention. The ?ange members may be used, how
1*; inch high and 1/2 inch wide immediately ad
' ever, in joining, not only thermoplastic pipe made
from the same or a different thermoplastic sub
jacent the bore.
In this instance leakage oc
stance from which the ?ange itself is made, but. 30 curred at the face of the union at a pressure of
140 pounds per square inch.
also, pipe made from thermosetting substances,
Although the ?ange of the invention has been
such as the phenol-formaldehyde condensation
described as being useful when'used in pairs as
products and their compositions. In ,many in
companion ?anges, it is obvious that solid ?anges
stances it is also advantageous to use such plastic
?ange members in joining together sections of 35 involving the novel features of the above-de
metal pipe. This- is particularly true when the
scribed bored ?anges may be employed for blank
pipe is made from a rare or expensive metal or
alloy, and the use of a ?ange union of'the corre
' ing off the ends of pipe or for covering manholes.
sponding alloy would consume undesirably large
and the like. It is also apparent that, instead of
threading the bore of the ?ange and screwing it
quantities of the metal. Flange unions employ 40 onto a threaded~pipe, the pipe and ?ange may be
welded or joined together in any other conven
ing the thermoplastic ?anges of the invention
suffer substantially no decrease in leaking pres
sure due to cold ?ow of the plastic even! when
ient manner.
We claim:
maintained under high working pressures for
1. A thermoplastic pipe ?ange adapted to be
long periods of time.
In a typical instance sections of a thermoplas
joined by means of bolts to a complementary -
?ange, the first said ?ange having a central bore
and a working face, the inner portion of which
adjacent the bore is a plane perpendicular to the
fabricated from a copolymer containing about
axis of the bore and the outer portion of which
92 per cent by weight of vinylidene chloride and
is inclined in the direction of the body of the
8 per cent of vinyl chloride plasticized with 10
percent of its weight. of di-alphaphenylethyl 50 ?ange at an angle of about 1° to about 5° from
said plane surface.
ether were threaded and screwed into ?anges
2. A thermoplastic pipe ?ange adapted to be
molded from the same composition. The ?anges
joined by means of bolts to a complementary
had an outside diameter of 4% inches and a cen
?ange, the ?rst said ?ange having a central bore
tral bore threaded to receive the 1%, inch pipe.
and a working face, the inner portion of which
They were 15% inches thick around the bore,
about 1%; inch thick outside the web, and about ' adjacent the bore is a plane perpendicular to the
axis of the bore and the outer portion of which is
one inch thick through the web. The web oc
inclined in the direction of the body of the_?ange
cupied a substantial portion of the area between
at an angle of about 2° to about 4° from said
. the thick hub surrounding the bore and the per
60 plane surface.
imeter of the ?ange. The ?anges were each pro
vided with four symmetrically spaced 5/8 inch bolt _
‘holes through the webbed portion. The surface
of the working face of each ?ange lay, for a dis
tic 1% inch I. D. pipe of standard dimensions
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