Note: Descriptions are shown in the official language in which they were submitted.
1137136
This invention relates to methods and apparatus for
forming plastic lined junctions in plastic lined pipe or conduit
commonly used for handling acids, caustics, salt water and other
corrosive fluids. More particularly, it relates to methods and
apparatus for joining uncoated ends of plastic lined pipe and
coating the end facings of said plastic lined pipe to provide
means for effecting a fully lined conduit when joints or sections
of lined pipe are joined. In one embodiment thereof, the invention
may be used to join sections of lined or un-lined pipe.
Plastic l;ned pipe has long been used for conducting
acids, caustics, salt water and other corrosive or abrasive fluids
which cause deterioration of metal pipes. Several effective
methods for forming plastic coatings over the entire inner surface
of the conduit are known in the art. For example, United States
Patent No. 3,422,856 to John J. Hunter, et al. and United States
Patent No. 3,758,361 to John J. Hunter disclose methods for
bonding tubular thermal adhesive liners throughout the entire
interior length of a pipe section and also the end facings thereof
so that the pipe sections, both threaded and non-threaded, may be
l 1137136
joined to form a fully lined conduit. Frequently, however, it is
necessary to remove a portion of a length of plastic lined pipe
fter the pipe is installed to insert a T or other conduit means
lr remove and replace a ruptured or faulty pipe section. ~7hen such
1 repairs or alterations are made in a pipe string, the pipe must
e cut and the open end thereof joined with another pipe or other
conduit means.
It will be observed, however, that when a plastic lined
l pipe has been cut, the end facing of the metal pipe is exposed.
¦ ~ccordingly, unless special precautions are taken to protect
the exposed end facing of the pipe, the exposed end will be in
¦fluid communication with the interior of the conduit when the
¦conduit is rejoined.
~ It will be appreciated, of course, ,hat ~ conventional
Iflange cannot be welded directly to pipe which has a plastic
¦Iliner since the heat generated by the welding process will
'ordinarily destroy the plastic liner. Furthermore, when pipe
~,repair5must be made in the field, particularly in thin-walled pipe ,
¦lor in conduits which have been buried, the open ends cannot be
2Q ¦,conveniently threaded to attach a flange or nipple. Accordingly,
alternative joining means is required.
Repair joints in plastic lined pipe may be effected
¦¦using the methods and apparatus disclosed in United States
IPatent No. 3,968,552 to John J. Hunter wherein an annular
Igroove is formed in the pipe section which is occupied by a
¦¦split ring to retain an attachment flange. Such repair joint
¦is effective in many applications but is somewhat limited in
its applicability since the groove is difficult to roll into
i. .
, 1137136
thick-walled pipe and the joint formed is not extremely rigid
I, i
when forme~ in some thin-walled ~ipe. Further~ore, forming
~a rolled groove in the external surface of a pipe lined with
,thin spray coatings and the like tends to rupture or dislocate
llthe coating.
In accordance with the present invention ~ethods
and apparatus are provided for forming a rigid fully lined junctioni
~in plastic lined pipe. An interconnecting flange is attached
Ito the pipe end which, in conjunction with a tapered compression
Icollar and a plastic lining flange, for~s a fully lined pipe
jjoint when the pipe is joined with an adjacent pipe section,
a T or other conduit means. A fully lined end face is achieved
~y forming an annular groove in the outer surface of the ?ipe
l'at a predetermined distance from the open end thereof, fitting a
Itapered compression collar or band which mates with the groove
¦over the end of the pipe, fitting a flange having an inner surface
which conforms to and mates with the compression collar and also
having a radially extending face which aligns with the open end
,of the pipe over the com~ression collar, and inserting a plastic
flange ~ember or collar within the open end of the pipe. ~he
plastic flange collar has a cylindrical body which fits within
the plastic liner in the pipe and an outwardly radiating flange
which mates with the exposed end face of the pipe, the end ~ce
of the com~ression collar and the face o the connection flange.
¦jThe cylindrical body extends into the plpe past the groove to
insure that any damage to 'he liner caused by the grooving is
covered with plastic. .~butting ends of lined pipe with exposed
end faces may thereby be joined to ~orm a fully lined junction
between two pipe sections which previously had exposed end iaces.
.
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li;~713~i
It will thus be observed that when repairs or alterations must
he made in string of buried pipe, an entire pipe section need not be re-
moved. Instead, only a small portion of the pipe need be exposed and re-
moved from the conduit and new portion substituted for the portion removed.
Using the teachings of this invention, a fully lined conduit is formed which
includes the short joint or other conduit means spliced into the conduit.
Furthermore, if a T or other apparatus must be installed in the pipe
string, only the immediately affected portion of the conduit need be
expdsed. Therefore, extremely rapid repairs and alterations may be made
~ in a lined conduit and, using the teachings of the invention, a fully
lined repair or alteration performed. In an alternative embodiment of the
invention, an annular groove is provided in the inner surface of the
flange member which carries a sealing gasket, such as an 0-ring or the
like, to form a seal between the flange and the pipe section, thereby
preventing leakage of fluids from the environment surrounding the junction
into the junction formed. The alternative embodiment may also be used
as the sole sealing means in forming junctions between sections of un-
lined pipe.
Broadly stated, the invention provides a method of lining the
end face of the open end of a pipe having a plastic liner bonded to the
internal surface thereof. The method comprises the steps of: (a) forming
an annular groove in the outer surface of said pipe at a predetermined
distance from the open end of said pipe; (b) encircling the end of said
- pipe in a collar extending axially from said groove to the end face of
the open end of said pipe and having an inwardly projecting lip mating
with said groove, said collar having a tapered external surface increasing
in diameter in the direction of the open end face of said pipe; (c) placing
a rigid flange on the outer surface of said pipe, said flange having a
central opening substantially conforming to the outer diameter of said
pipe and having an internal annular shoulder and an axially tapered internal
surface mating with said tapered external surface of said collar; and
li37136
(d) inserting a plastic end face liner in the open end of said pipe,
sa;.d end face li.ner comprising a tubular body hav;ng outer dimensions
substantially conforming to the inner dimensions of said liner in said
pipe and having a flange extending radially from one end of said tubular
body, said radially extending flange mating with both the open end face
of said pipe and the end face of said collar.
Another broad aspect of the invention provides a coupling joint
t ~ nterconnecting the open ends of two~pipë sections, each p;pe section
having a plastic liner on the internal surface thereof. The coupling joint
0 comprises: (a) a plastic end face liner positioned within the open end
of each of said pipe sections, said end face liner comprising an open
cylindrical body having outer dimensions substantially conforming to the
internal diameter of said plastic l;ner and having an outwardly radially
projecting flange adjacent one end thereof mating with the end face of the
open end of said pipe section; (b) an annular groove in the external
surface of each of said pipe sections at a predetermined distance from the
open end thereofj (c) a compression collar forming an axially elongated
ring encircling the open end of each of said pipe sections, said compression
collar having an inwardly projecting lip mating with said groove and a
tapered outer diameter increasing in diameter from said groove to the
opposite end face thereof, the said opposite end face thereof lying in
substantially the same plane as the end face of said pipe; (d) a rigid
flange member having a central opening of non-uniform diameter encircling
each of said pipe sections, each said flange member having a first face
lying substantially in the plane of the open end face of said pipe and an
opposite face axially removed from said first face, the internal diameter
of the flange member adjacent said opposite face substantially conforming
to the external diameter of said pipe section and the internal diameter
of said flange member adjacent said first face substantially conforming
the external diameter of said compression collar at the face thereof lying
in the plane of said end face of said pipe, the internal diameter of the
il3~7136
flange member further tapering to mate with the tapered external surface
of sai.d compression collar and fonm a shoulder engaging the end face
of the compression collar opposite the open end face of said pipe; and
(e) means for drawing said rigid flange members axially together and
joining the flanges on said end face liners in an abutting relationship.
The invention also broadly provides a coupling joint inter-
connecting the open ends of twotpipe sections, each pipe section having
a plastic liner on the internal surface thereof, comprising: (a) a plastic
end face liner positioned within the open end of each of said pipe
sections, said end face liner comprising an open cylindrical body having
outer dimensions substantially conforming to the internal diameter of said
plastic liner and having an outwardly radially projecting flange adjacent
one end thereof mating with the end face of the open end of said pipe
section; (b) a compression collar forming an axially elongated ring en-
circling the open end of each of said pipe sections, said compression collarhaving inwardly projecting means for engaging said pipe and a tapered external
surface decreasing in diameter from the open end of the pipe with the large
diameter thereof lying in substantially the same plane as the end face
of said pipe, (c) a rigid flange member having a central opening of
non-uniform diameter encircling each of said pipe sections, each said
flange member having a first face lying substantially in the plane of the
open end face of said pipe and an opposite face axially removed from said
first face, the internal diameter of the flange member adjacent said op-
posite face substantially conforming to the external diameter of said pipe
section and the internal diameter of said flange member adjacent said
first face substantially conforming to the external diameter of said com-
pression collar at the face thereof lying in the plane of said end face
of sa;d pipe, the internal diameter of the flange member further tapering
to mate with the tapered external surface of said compression collar; and
(e) means for drawing said rigid flange members axially together and joining
the flanges on said end face l;ners in an abutting relationship.
- 5b -
1137136
In another broad aspect of the invention an apparatus is
provi.ded for lin;ng the end face of the open end of a pipe having a
plasti.c liner bonded to the internal surface thereof and joining said open
end of said pipe to other lined conduit means. The apparatus comprises:
(a) an end face liner comprising a cylindrical body, the outer dimensions
thereof substantially conforming to the inner diameter of said plastic
liner in said pipe and having a radially extending flange mating with
the end face of said pipe, (b) a band encircling the end of said pipe, said
band having inwardly projecting means for engaging said pipe and a tapered
outer surface decreasing in diameter from the open end of said pipe; and
(c) a rigid flange having a central opening therein encircling said
pipe and said band, said central opening having dimensions conforming to
and mating with the outer dimensions of said band.
Another broad aspect of the invention provides an apparatus
for joining the open end of a pipe to other conduit means, comprising:
(a) an axially elongated band encircling the end of said pipe, said band
having inwardly projecting means for engaging said pipe and a tapered
outer surface decreasing in diameter from the open end of said pipe; and -;~
(b) a rigid flange having a central opening therein encircling said pipe
and said band, said central opening having non-uniform dimensions, the
internal surface of said central opening nearest the open end of said
pipe conforming to and mating with the tapered outer surface of said band
and the internal surface of said central opening nearest the opposite
face thereof conforming to and mating with the external surface of said
. pipe.
Other features and advantages of the invention will become
more readily understood from the following detailed description taken
in connection with the appended claims and attached drawings in which:
Figure 1 is a sectional view of the open end portions of
two lined pipe sections joined ;n accordance ~ith one embodiment of the
invention;
5c -
1 1 3 7 1 3~;
Figure 2 is a sect;onal view of the open end portion of a
pipe sect;on employing an alternative embodiment of the invention; and
Figure 3 is a sectional view of the open end of a pipe
section employing yet another alternative embodiment of the invention.
- 5d -
~i37136
As illustrated in the dra~lings the opposed open ends
of two sections of lined metal pipe may be joined in accordance
~ith the invention to form a fully lined junction. Each pipe
Isection 10 may be the open end of any conventional conduit formed
If~om either threaded or non-threaded pipe joints having a liner 11 i
on the internal surface thereof. Liner 11 may be a conventional
tubular liner formed of thermal plastic, such as polyvinyl chloride
'or other plastic, or may be a protective lining Cormed in place
I~s by spraying or the like as is well known in the art.
!Fonventionally, liner 11 is bonded to the internal surface of
¦the pipe 10 to form a plastic lined conduit.
¦I When a section of a conduit formed by joints of ~ipes
such as pipe 10 is removed, the removal is usually accomplished
Iby merely cutting through the pipe. The pipe m~y be cut for any of;
various reasons, such as to remove a faulty, leak~ or damaged
'section or to install a T or other apparatus. ~owever, when a
portion of the conduit is removed, such as by sawing or the like,
the pipe 10 and the liner 11 are both severed in the same plane
Ijleaving an open end. The end ~ace 12 of the pipe 10 is thus
ZO exposed and not coated with the liner.
If the pipe sections 10 are to be joined to each other
or with a substitute pipe section, T or the like, means ~ust be
provided to protect the end faces 12 of the pipe 10.
,¦ As illustrated in the drawings an annular groove 13 is
formed in the external surface of pipe 10 at a predetermined
distance from the end face 12. The groove 13 may be formed ~y
a conventional grooving tool which cuts a relatively flat-bottomed
rectangular groove 13 as illustrated in Figure 1 or may be a
semi-circular groove formed by rolling or the like as illustrated
.,
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11;~7136
I
,`in Figure 2. A plastic end face liner 14 is then positioned within
the open end of pipe 10. End face liner 14 comprises an open-ended
llcylindrical body, the outer dimensions of which substantially
!Iconform to the internal dimensions of liner 11 in pipe 10. The
lend face liner 14 includes a radially extending flange 15 which
¦radiates outwardly from one end of the body and ;oates with the
end face 12 of the pipe 10.
The end face liner 14 is preferrably of the same naterial¦
;as liner 11. Therefore end face liner 14 may be bonded to liner 11
Iwith a suitable solvent such as ~ethyl ethyl ketone or any other
suitable solvent or conventional epoxy cement or the like,
depending upon the material of the liner 11 and end face liner 14.
A metal compression collar 16 is then fitted over the outer
,isurface of the open end of pipe 10.
1 Compression collar 16 preferrably comprises a pair of
¦Isemi-circular steel bodies which mate to form an axially elongated
,ring or band. Alternatively, compression collar may be I unitary
split ring which is expandable to fit over the end of the oipe 10.
~llThe internal diameter of the co~oression collar 16 is preferrably
I!the same as the external diameter ol the pipe 10 and includes an
inwardly projecting means to position the collar 16 and prevent
axial movement of the collar 16 T~ith respect .o the pipe 10. The
l'.inwardly projecting means may be a flange or lip 17 which mates
¦jwith groove 13 where a groove 13, either rectangular or rounded
¦las sho~n in Figures 1 and 2, ~espectively, is formed. The .~xial
length of compression collar 16 is preferrably identical with the
'.predetermined distance of the groove 13 from 'he open end face 1?.
of the pipe so that the end face of the compression collar opposite
the llp 17 lies in t _ sa~e plane as the end 'ace 1~ of ~e pipe 10
.1 .
-7-
~137136
In the embodiment illustrated in Figure 3, all or part of the
internal surface of the compression collar 16 is provided with
Igripping ridges or teeth 17a which grippingly engage the outer
¦surface of the pipe. The outer surface 18 of compression
l¦collar 16 is tapered, the external diameter increasing in the
direction of the end ther~of lying in the plane of end face 12 of
pipe 10.
¦ A rigid flange 20 having a central opening 21 is
~ositioned over the end of pipe 10 prior to assembly of the
compression collar 16 and insertion of the end face liner 14. The
~l igid flange 20 has a centrally located opening 21 of non-unifor~
¦jdiameter. The smaller internal diameter of the opening in
flange 20 is substantialy the same as the external diameter of
¦pipe 10 and is located in the portion thereof at the edge removed
¦,from the open end of the pipe 10. The internal diameter of the
.,flange 20 is greatest at the face thereof lying in the plane of
the open end face 12 of the pipe 10. The larger internal diameter
is tapered in the same direction as the outer surface 18 of the
'compression collar 16 so that the tapered internal surface 27
!mates with the tapered external surface 18 of the compression
.collar 16 and further forms a shoulder 19 which mates with the
edge of the compression collar 16 adjacent lip 17 as shown in
Figures 1 and 2. The axial length of the tapered internal diameter
lsurface 27 of the flange 20 is substantially the same as or slightly
Illess than the axial length of compression collar 16.
¦, Flange 20 includes a plurality of holes 22 parallel
with the central opening 21 and disposed around the periphery
thereof through which connector bolts 23 may be passed to
'accomplish coupling of one pipe joint to another pipe joint or
other apparatus.
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1137136
For connecting two open pipe ends, each having an
exposed end face 12 as illustrated in the drawings, the coupling
may be formed by abutting the ends of the pipes. ~he faces of
!the radially extending flanges on end face liners 14 are Arawn
!together by bolts 23 passing through holes 22. It will be
¦lobserved that as the flanges 20 are drawn together by connector
bolts 23, the tapered internal surfaces 27 mate with the tapered
jlexternal surfaces 18 on the compression collars 16. Thus the
'compression collar 16 is radially compressed inwardly by the
l,flange 20 to maintain the lip 17 securely engaged in groove 13.
The lip 1~ thus exerts axial force on the pipe 10 through
,shoulder 19 on the internal surface of the flange 20 engaging
the end face of the compression collar 16 to draw the end face
j~liners 14 uniformly and snugly into mutual contact. Alternatively,
~¦in the e~bodiment of Figure 3, radial compression of the collar 16
'causes-teeth 17a to securely engage the pipe 10 and axial force
'is applied to the collar 16 through shoulder 19 to draw the ends
of the pipe sections 10 together.
il It will be readily appreciated that the flanges 15 on
20 end face liners 14 mate not only with the end faces 12 of ?ipes 10,
but also with each other and with the end Paces of compression
collars 16 and the opposing faces of flanges 20. Accordingly, a
suitable solvent or cement may ~e applied to the flanges 15
iiimmediately prior to assembly to form a fully bonded and sealed
,Iplastic lined coupling.
In some cases, particularly those involving relatively
thin-walled pipe internally coated with a formed-in-olace liner
such as a sprayed coating, formation of the groove 13 in the
external surface of the pipe may cause damage to the liner 11 on
,the internal surface of the pipe in the immediate vicinity of the
groove 13. For example, the liner may crack or become disengaged
,
_g_
1~3713~i
;from the pipe wall, thus exposing the metal pipe t~all to fluid
passing through the conduit. In order to protect the pipe wall
from any such damage which may occur, the tubular body portion
of the end face liner 14 should extend into the lined pipe 10
iwell past the groove 13 and be securely bonded to the liner 11.
¦,In this manner, any cracks or the like formed in liner 11 by
formation of the groove 13 will be covered by the end face
¦¦liner 14, thus insuring the formation of a fully lined conduit.
¦¦ As illustrated in Figure 3, an annular groove 30 may be
10 l,formed in the internal surface of the opening 21 in flange 20
¦Iwhich engages the pipe 10 and sealing means, such as an O-ring 31
or the like, fitted therein. The seal formed by the O-ring 31
prcvides an external seal to prevent fluids from the external
~environment from entering the joint formed. Thus, when the
ilconduit is used in a corrosive environment or buried, etc.,
Ilexternal fluids may not leak into the coupling mechanism to
,contaminate and corrode the joint-forming mechanism.
It will be apparent that the groove and O-ring embodiment
'may be used in combination with any embodiment of the compression
collars 16 shown and described. I~hen used in forming lined
junctions in lined pipe, the sealing groove and O-ring serve
primarily to prevent leakage of external fluids into the
joint-forming apparatus. ~owever, it should be observed that
~the elements of the invention shown may be used as shown and
described without the plastic end face liner 14 to form junctions
;between un-lined pipe sections. In this case, a gasket (not
,shown) may be placed between the abutting faces of flanges 20 to
replace flange 15 and the sealing gasket and the O-ring 31 form
~a fluid-tight seal between the abutting ends of the pipe sections.
--10--
li37136
The interrelationship between the collar 16, the flange 20 and the
ends of the pipe 10 are, of course, the same for lined as well as
un_lined pipe. Thus the hardware designed in accordance with the
invention for forming fully lined joints may also be used for
S forming un-lined joints.
It will be observed that the method and apparatus
described herein may be used on practically any size of metal
~pipe, either threaded or unthreaded. The coupling may readily
Ibe performed in the field on buried pipe with only minimum
exposure of buried line. Furthermore, the rigid flanges 20 may
pe adapted to mate with each other, as showm in Figure 1, or
adapted to mate with other apparatus such as a T or the like
iwhich already has an end face liner. Since the collar 16 extends
,axially from the shoulder 19 in the flange 20 to the open end
Iface 12 of pipe 10, the collar 15 reinforces the end of the pipe
so that the coupling formed by the flange 20 is rigid and stable.
Furthermore, since the outer surface 18 is tapered to mate with
the tapered inner surface 27 of the flange, the collar 16 is
radially compressed about its full radial periphery to form
intimate contact with the pipe yet prevent crushing of the pipe.
Thus the collar 16, whether provided with teeth 17a or lip 17,
securely engages the pipe and stabilizes the junction.
~ hile the invention has been described with particular
i,reference to specific embodiments thereof, it is to be understood
,that the forms of the invention sho~m and described in detail are
to be taken as preferred emoodiments of same, and that various
changes and ~odifications thereof may be resorted to without
`departing from the spirit and scope of the invention as ~efined by
the appended claims.
