Note: Descriptions are shown in the official language in which they were submitted.
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A PROTECTIVE END CAP FOR EXTERNAL PIP~ THREADS
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates generally to thread
protectors, and more specifically to a protective end cap
for protecting external pipe threads at the end of a pipe,
tubing, casing or the like.
Description of the Prior Art
U.S. Patent No. ~,079,756 issued ~arch 21, 1978
1~ to Kenneth A. Smiley discloses a plastic protective end
cap having a radially inwardly curved end portion over-
lapping the end surface of the threaded end of a pipe.
Although the plastic curved end portion offers some
protection to the threaded end of the pipe from light,
15 axially directed impact forces, damage to the threaded end
may occur if such forces are large. Such damage may
necessitate retapping the damaged threads, or cutting off
the damaged pipe end and rethreading it.
It is further known to provide metal end caps
20 having inner peripheral threads for threadingly engaging
external pipe threads. Axially directed impact forces on
such metal end caps can cause thread damage, resulting in
locking or cross--threading of the external pipe threads
which may prevent rernoval of the end cap. Such damage may
25 necessitate retapping the damaged threads, or cutting off
the end cap and rethreading the pipe end.
SUMMARY OF THE INVENTION
It is a primary object of the present invention
to provide a protective end cap for protecting external
30 threads on the end portion of a pipe or the like.
To this end the invention consists of a protective
end cap for protecting the external threaded portion and
end portion oE a pipe comprising: a metal sleeve having a
first radially inwardly curved end portion substantially
.~
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overlapping the end of said pipe; a substantially rigid
metal insert disposed between said inwardly curved end
portion of said sleeve and said end of said pipe; and a
resilient plastic core having a first portion disposed
between said sleeve and the threaded portion of said pipe
and a second impact aDsorbing inwardly curved end portion
disposed bet~een said metal insert and said inwardly
curved end portion of said sleeve.
One advantage of this invention is to provide end
caps for protecting external threads at the end of a pipe
or the like that are of simple design and construction, and
easy to manu~acture. This is achieved by using common
sleeves of one design into which inner cores of varying
internal thread design are inserted and locked. The
internal thread designs correspond to the varied shapes of
the external threaded pipe end portions presently available
on the market.
Another advantage of this invention is to provide
an end cap formed from a core and sleeve having unique
curved mating front end portions overlapping and in engage-
ment with the end surface of a pipe when the end cap i9
mounted thereon. The curved front end portions of the end
cap, preferably when reinforced by a metal insert, protect
the externally threaded pipe end portion from damage due
to forces directed against the front end portion. Damaged
pipe end portions may necessitate costly repair operations
such as retapping the external threads, or cutting off the
damaged pipe end portion and rethreading the pipe end.
The invention and its advantages will become more
apparent from the detailed description of embodiments
thereof presented below.
BRIEF DESCRIPTION OF THE DRAWING
In the detailed description of embodiments of the
invention presented below, reference is made to the
accompanying drawing, in which:
FigO 1 is a segmental perspective view of a
preferred embodiment of a protective end cap mounted on
external threads at the end of a pipe;
Fig. 2 is a segmental enlarged section view taken
substantially along line 2-2 of Fig. 1;
Fig. 3 is a segmental section view similar to Fig.
2 of another embodiment of the protective end cap mountable
on external threads of a different type;
Fig. 4 is a view similar to Figs. 1 and 2 of a
slightly modified protective end cap mounted on external
threads of still another type;
Fig. 5 is a segmented view in section of another
embodiment of the protective end cap of this invention;
Fig. 6 is a segmental view similar to Fig. 5 of
still another embodiment of the protective end cap of this
invention;
Fig. 7 is a segmental section view of a protective
end cap showing a different way of securing the inner core
to the outer sleeve;
Fig. 8 is a segmental end view of the end cap of
Fig. 7; and
Fig. 9 is a segmental section view of an end cap
showing a splined connection between the inner core and
outer sleeve~
DET~ILED DESCRIPTION OF EMBODIMENTS OF T~IE INVENTION
With reference to Figs. 1 and 2, a preferred
embodiment of a protective end cap 10 is disclosed for
protecting external Butress type threads 12 on the end
portion of any suitable pipe, conduit, casing or the like
designated 14. End cap 10 is formed from two interlocking
parts, an outer sleeve 16 and an inner core 1~.
Outer sleeve 16 is preferably made from any
suitable rigid material such as steel. Sleeve 1~ is
preerably of a cylindrical configuration throughout most
of its length. The sleeve further has a radially inwardly
curved outer end portion 20 overlapping the end surface 22
of pipe 14 when the end cap is mounted on the end of a
pipe.
Inner core 18 i6 preferably made of any suitable
high-impact plastic. ~ore 18 has an inner threaded
tapered surface 24 for threadingly engaging tapered
external threads 12 on pipe 14 when end cap 10 is screwed
onto the end of the pipe. The interengaging threads 12,
24 hold the end cap on the pipe and provide a seal so that
moisture does not contact the pipe threads. Core 18
further has an outer peripheral surface 26 and curved
outer end portion 28 conforming to a portion of the inner
peripheral surface 30 of sleeve 16. End portion 28
further has a radially inwardly extending section 27
interposed between sleeve end portion 20 and pipe end
surface 22 of a width or thickness approximately 0.10 cm
(0.04 inch). Core 18 also has a left or inner end rim 29
of greater diameter than sleeve end 33 to protect the
sleeve end from damage from external forces or blows, and
to prevent the sleeve end from damaging expose~ pipe
threads on other pipes during handling. End rim 29 has a
tapered edge 31 for deflecting blows directed against the
rim.
Sleeve 16 and core 18 are secured or locked
together by any suitable means SUCtl as bonding, an
interference fit, or as shown in the drawing, one or more
openings 32 in the sleeve receiving complementary
projections 34 on the core when it is pressed into mating
engagement with the sleeve. The inner diameter of sleeve
16, outer diameter of core 18, and inner tapered threaded
surface 24 of the core are designed, along with rigid
sleeve 16, to place the external and internal threads 12,
24 respectively under sufficient Lorce to sealingly secure
end cap 10 to pipe 14 when the end cap is screwed tightly
thereon by any suitable tool, such as a pipe wrench or the
like, not shown. Although openings 32 and projections 34
are shown as circular, they, of course, can be of any
r ~
other suitable shape, such as square, rectan~ul~r, or the
like.
With reference to Figs. 3 and 4, parts simiLar to
parts shown in Figs. 1 and 2 will be denoted by the same
numerals primed and do-lble-primed, respectively. In these
figures, end caps 10', 10" of thiS invention are shown
applied to two different types of externally threaded
pipes 14', 14" respectively. In these figures, the
sleeves 16', 16" are substantially identical to sleeve 16
of Fig. 1, and the inner cores 18', 18" have a common
outer diameter, but different shaped inner peripheries
24', 24" conforming to the external threads 12 ' 12a
respectively of the pipes. Accordingly, manufacture of
end caps for any type of externally threaded pipe end
portion is facilitated by providing common sleeves 16,
16', 16" of one design, and inner cores 18, 18', 18" of
varied design. The inner cores have a common outer
diameter and surface 26, 26', 26", and different inner
threaded surfaces 24, 24~, 24~ designed to conform to the
different externally threaded pipes 14, 14', 14" shown in
the drawing, and others that may be available on the
market.
The Fig. 4 end cap 10" is further modified to
protect the metal seaL at the left or inner end of the end
cap. This is achieved by a metal ring 23 secured to the
end cap by any suitable means, such as spot welding or the
like. Ring 23 extends over and p-rotects the inner end of
core 18", and assists in maintaining a tight seal at the
left end of the end cap.
3 With reference to Fig. 5, curved end portion 28
of Figs. 1-4 is modified to provide a radially extending
section 27 of greater thickness. In this embodiment,
section 27 has a width approximately one and one-half
times the pitch diameter of the pipe threads, or
approximately 0.~6 cm (0.18 inch~. With a section 27 of
this thickness, any blow imparted to end portion ~0 will
axially move end cap 10 relative to the pipe a sufficient
distance to cause most of the core threads 24 to shear
3r~h~
off. This will dissipate a large portion of the ener~y
from the blow and provide greater protection for the pipe
threads.
With reference to Fig. 6, an annular m~tal in6ert
36, such as a washer, is embedded in or associated with
section 27 of core 1~. Washer 36 may ~e emb~dded in
~ection 27 during the molding operation. Alternatively,
section 27 may be provided with an annular slot, and
w~sher 36 split to allow contraction of the washer for
in~ertion into the groove. When released, the washer
oxpand~ fllllng the ~lot. Curve~ en~ portion 2~
of sleeve 16 and section 27 of core 18 protectively
overlap the pipe end surface 22 with metal washer 36 in
alignment with the pipe end surface. Accordingly9 any
external force directed against the curved end ~0 of the
sleeve by any means such as dropping the pipe on the
capped end, for example, i9 absorbed by curved end portion
20, section 27 and metal wastler ~6 as they are forced
toward the pipe end surface 22. rhis force absorption
prevents damage to tt-e external and internal threads 12,
24, respectively. Such dalnage, if not prevented, might
necessitate retapping the external threads 12, or cutting
off the damaged end of pipe 14 and rethreading it.
Core 18 of the end cap is further provided with a
closure member 46 integral with and depending from section
27 to prevlent dirt or the like from entering a pipe 14
when the end cap is mounted thereon. Closure member 46 is
a thin membrane having one or Inore tear flaps 4~ defined
by score lines 50. ~ach fla~ 48 further has an opening 52
3 extending therethrough to provide proper ventilation of
the pipe opening or cavity. 'rhe opening 52 further allows
in6ertion of a finger or the like therethrou~h to enable
tearing out the flap 4B along its score lines 50. Removal
of the flaps 48 allows insertion of any suitable end cap
removing ~ool, not shown, into the pipe for hammering a
shoulder 54 on section 27 of the core for relnovill~ an en~
cap lQ that is stuck on the pipe, i.e. canno~ be removed
!3, a~ ? ~
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by unscrewing the end cap. In Fi~s. 1-3, closure member
46 is the ~ame width as, and an extension of, section 27.
~l In Fig. 5, closure member 46 extends from the inner edge
of section 27, whereas in Fig. 6 it extends from section
27 between washer 36 and sleeve end portion 20.
Preferably, the inner suriace of melllber 46 i~ in ~lignment
with the outer surface of washer 36 to provide a guide for
insertion of washer 36 into a receiving slot in section 27.
Referring to Figs. 7 and 8, another means for
locking together a sleeve 16 and core 18 is shown. The
locking means comprises notches 40 along the outer curved
end portion 20 of sleeve 16 for receiving flexible fingers
42 on core 18. The fingers 42 have tapered ribs 44 which
are flexed downwardly as the fingers are pressed through
notches 40, and then flex upwardly in front of curved
portion 20 of sleeve 16 to lock the sleeve to the core.
With reference to Fig. 4, means such as
key-grooves 41 on sleeve 16 and splines 43 on core 18 are
shown for guiding the core into the sleeve of an end cap
so that projections 34 or fingers 42 on the core will line
up with and enter openings 32 or notches 40 respectively
in the sleeve.
The invention has been described in detail with
particlar reference to preferred embodiments, but it will
be understood that variations and modifications can be
effected withi,n the spirit and scope of the invention as
described. For example, instead of providin~ a
cylindrical sleeve 16, the sleeve could be tapered or
frusto-conically formed. In such a modification, the
outer peripheral surface 26 of core 18 would also be
tapered or frusto conical to conform to the inner surface
30 of the sleeve. Also, core 18 could be formed without
tear flaps 48, or without a closure member 46.
