GB2093426A - A protective cap for pipe threads - Google Patents

Abstract

An external pipe thread protective end cap 10 is provided comprising an outer sleeve 16 and an inner tubular plastic core 18 interlocked therewith. The core has threads 24 on its inner periphery threadingly engageable with the pipe threads 12 when the protective end cap is screwed thereon. The sleeve 16 and core 18 have mating portions 20 and 28 which overlap and engage the end surface 22 of the pipe when the protective end cap is threaded onto the pipe. The curved outer end portion of the core preferably has a metal insert (36) associated therewith, and an integral closure member 46 with tear-away flaps 48. <IMAGE>

Description

SPECIFICATION A protective end cap for external pipe 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. 4,079,756 discloses a plastic protective end cap having a radially inwardly curved end portion overlapping 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, 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 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 crossthreading of the external pipe threads which may prevent removal of the end cap. Such damage may 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 threads on the end portion of a pipe or the like. The end cap comprises an outer sleeve for receiving a plastic tubular core. Means are provided on the sleeve and core to lock the two together. The core further has thread means on its inner periphery for threadingly engaging external threads on a pipe end when the end cap is screwed thereon.

In a further aspect of the invention, the locking means for securing the sleeve and core together comprises openings in the sleeve receiving projections on the core.

In another aspect of the invention, the sleeve and core are provided with mating, radially inwardly curved outer end portions. When the end cap is screwed onto the end of a pipe, the curved outer end portions sealingly engage, overlap and protect the end surface of the pipe.

In still another aspect of the invention, a preferably annular metal insert is associated with or embedded within the curved outer end portion of the core.

In an additional aspect of the invention, the curved outer end portion of the core has an integral closure membrane for closing off the core.

The closure membrane further has one or more tear flaps to provide access therethrough.

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 manufacture. 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 curving mating front end portions overlapping and in engagement with the end surface of a pipe when the end cap is 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 the invention presented below.

BRIEF DESCRIPTION OF THE DRAWING In the detailed description of the invention presented below, reference is made to the accompanying drawing, in which: Fig. 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 segmented 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.

DETAILED DESCRIPTION OF THE 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 1 6 and an inner core 18.

Outer sleeve 16 is preferably made from any suitable rigid material such as steel. Sleeve 1 6 is preferably 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 is preferably made of any suitable high-impact plastic. Core 1 8 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 1 8 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 1 6. 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 exposed pipe threads on other pipes during handling. End rim 29 has a tapered edge 31 for deflecting blows directed against the rim.

Sleeve 1 6 and core 1 8 are secured or locked together by any suitable means such 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 1 2, 24 respectively under sufficient force 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 other suitable shape, such as square, rectangular, 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 double-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 1 6', 1 6" are substantially identical to sleeve 1 6 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 1 2', 12" respectively of the pipes. Accordingly, manufacture of end caps for any type of externally threaded pipe end portion is facilitated by providing common sleeves 1 6, 16', 1 6" of one design, and inner cores 18, 1 8', 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 protects the inner end of core 18", and assists in maintaining a tight seal at the left end of the end cap.

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 0.46 cm (0.18 inch). With a section 27 of this .thickness, any blow imparted to end portion 20 will axially move end cap 10 relative to the pipe a sufficient distance to cause most of the core threads 24 to shear off. This will dissipate a large portion of the energy from the blow and provide greater protection for the pipe threads.

With reference to Fig. 6, an annular metal sheet 36, such as a washer, is embedded in or associated with section 27 of core 1 8. Washer 36 may be embedded in section 27 during the molding operation. Alternatively, section 27 may be provided with an annular slot, and washer 36 split to allow contraction of the washer for insertion into the groove. When released, the washer expands filling the slot. Curved end portion 20 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. Accordingly, any external force directed against the curved end 20 of the sleeve by any means such as dropping the pipe on the capped end, for example, is absorbed by curved end portion 20, section 27 and metal washer 36 as they are forced toward the pipe end surface 22.

This force absorption prevents damage to the external and internal threads 1 2, 24, respectively.

Such damage, 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 prevent 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 more tear flaps 48 defined by score lines 50. Each flap 48 further has an opening 52 extending therethrough to provide proper ventilation of the pipe opening or cavity. The opening 52 further allows insertion of a finger or the like therethrough to enable tearing out the flap 48 along its score lines 50. Removal of the flaps 48 allows insertion of any suitable end cap removing tool, not shown, into the pipe for hammering a shoulder 54 on section 27 of the core for removing an end cap 10 that is stuck on the pipe, i.e. cannot be removed by unscrewing the end cap.In Figs. 1-3, closure member 46 is the same width as, and an extension of, section 27. 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 surface of member 46 is in alignment with the outer surface of washer 36 to provide a guide for insertion of washer 36 into a receiving siot in section 27.

Referring to Figs. 7 and 8, another means for locking together a sleeve 1 6 and core 1 8 is shown. The locking means comprises notches 40 along the outer curved end portion 20 of sleeve 1 6 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 1 6 to lock the sleeve to the core.

Withe reference to Fig. 9, means such as keygrooves 41 on sleeve 16 and splines 43 on core 1 8 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 particular reference to preferred embodiments, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described. For example, instead of providing 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 1 8 could be formed without tear flaps 48, or without a closure member 46.

Claims (9)

1. A protective end cap for protecting the external threads on the end portion of a pipe comprising: a sleeve; a plastic tubular core insertable within said sleeve; means on said sleeve and core for locking said sleeve and core together to form a protective cap; and thread means on the inner periphery of said core threadingly engageable with the external threads on the pipe when the protective end cap is screwed onto the end portion of the pipe.

2. A protective end cap according to claim 1 wherein said sleeve has an opening, said core has a projection, and said locking means comprises said opening in said sleeve receiving said projection on said core.

3. A protective end cap for protecting the external threads on the end portion of a pipe comprising: a metal sleeve having a first radially inwardly curved outer end portion; a plastic tubular core insertable within said metal sleeve and having a second radially inwardly curved outer end portion mating with said first curved end portion, said core having thread means on its inner periphery threadingly engageable with the external threads on a pipe; and means on said sleeve and core for locking said sleeve and core together to form a protective end cap whereby when said protective end cap is threaded onto the external pipe threads, said first and second curved outer end portions protectively overlap the end surface of the end portion of the pipe.

4. A protective end cap according to claim 3 wherein said sleeve has an opening, said core has a projection, and said locking means comprises said opening in said sleeve receiving said projection on said core.

5. A protective end cap according to claims 3 or 4 wherein said second outer end portion has an annular inner surface for engaging the end surface of the end portion of the pipe when the protective end cap is threaded thereon, and an annular metal insert is mounted adjacent said inner surface.

6. A protective end cap according to claims 3 or 4 wherein an annular metal insert is mounted within said second outer end portion.

7. A protective end cap according to claims 3 or 4 wherein an annular metal washer is mounted within said second outer end portion and lies in a plane parallel to said inner surface of said second outer end portion.

8. A protective end cap according to claims 3 or 4 wherein said second outer end portion has an integral closure member for closing off said core, said closure member further having at least one tear flap to provide access therethrough.

9. A protective end cap for protecting the external threads on the end portion of a pipe substantially as hereinbefore described with reference to the accompanying drawings.