High Strength Pipe Thread Protector

Abstract

A device for protecting a portion of a pipe is provided. The device comprises a disk-shaped base having a proximal base surface and a distal base surface. An annular connector extends proximally from the base and has an interior connector surface and an exterior connector surface and a threaded engagement portion configured for threadably engaging the series of pipe threads. The device further comprises a ridge extending distally from at least a portion of the outer edge of the distal base surface. The ridge has a ridge height, an outer ridge surface and an inner ridge surface. The device also comprises a plurality of ribs extending distally from the distal base surface and radially inward toward the base axis from the inner ridge surface.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 61/552,783 filed Oct. 28, 2011, which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

The invention relates generally to the protection of pipe from damage and, more specifically, to a thread protection device (or “thread protector”) for protecting end of a pipe and the threads adjacent the end of a pipe from impact loads.

Pipes, such as those used for oil or gas drilling, are often connected at the ends using a male thread portion at one end (the pin end) of a section of pipe that is threadably engageable to a female thread portion (the box end) of another section of pipe.

The threaded ends of a pipe are subject to damage when not in actual use. Pipes are often dropped or impacted by other outside forces. “Thread protectors” are commonly used to protect the threaded ends of a pipe.

Thread protectors must prevent substantial impact energy from reaching the pipe and damaging the threads during handling and transportation. This may be accomplished by a thread protector that plastically deforms upon impact, dissipating impact energy away from the pipe threads in the form of heat.

SUMMARY OF THE INVENTION

An aspect of the present invention provides a device for protecting a portion of a pipe having a pipe end, a pipe axis and a series of pipe threads adjacent the pipe end. The device comprises a disk-shaped base having a proximal base surface that faces the pipe end when the device is installed on the pipe and a distal base surface. The base is a body of revolution about a base axis that is coaxial with the pipe axis when the device is installed on the pipe. An annular connector extends proximally from the base and has an interior connector surface and an exterior connector surface and a threaded engagement portion configured for threadably engaging the series of pipe threads for securing the device to the pipe. The device further comprises a ridge extending distally from at least a portion of the outer edge of the distal base surface. The ridge has a ridge height, an outer ridge surface and an inner ridge surface. The device also comprises a plurality of ribs extending distally from the distal base surface and radially inward toward the base axis from the inner ridge surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the following detailed description together with the accompanying drawings, in which like reference indicators are used to designate like elements, and in which:

FIG. 1 is a top view of a protection device according to an embodiment of the invention;

FIG. 2 is a section view of a protection device according to an embodiment of the invention;

FIG. 3 is a section view of a protection device according to an embodiment of the invention;

FIG. 4 is a top view of a protection device according to an embodiment of the invention; and

FIG. 5 is a section view of a protection device according to an embodiment of the invention;

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention provides thread protectors that can be threaded to the end of a pipe and that are able to withstand impact energy from various angles and dissipate it in order to protect the pipe end and the threads at the pipe end. In particular, thread protectors of the invention are capable of meeting the requirements of American Petroleum Institute (API) Specification 5CT/ISO 11960 Annex I, which is incorporated herein by reference. Thread protectors according to the invention have structural features that allow reductions in the amount of material needed, which serves to minimize weight and production costs. The thread protectors of the invention may be made from a variety of materials, depending on the desired strength properties and the anticipated environmental conditions in the field.

The thread protectors of the invention may be configured for threadable engagement with any standard threaded pipe. Throughout the present specification the terms “proximal” and “distal” are used to describe the relative placement and direction of features of the disclosed thread protectors relative to the pipe when the thread protector is installed. As used herein “proximal” means in the direction the pipe extends from the pipe end and “distal” means in the direction away from the pipe, in each case, along the centerline axis of the pipe. Thus, when installed, the proximal end of the thread protector is oriented in a direction toward the pipe and the distal end of the thread protector is oriented in a direction away from the threaded end of the pipe.

In an illustrative embodiment of the present invention a thread protector has a disk-shaped base with a proximal base surface and a distal base surface. The proximal base surface is attached to an annular connector that extends proximally in the direction of the pipe. The annular connector has an interior surface and an exterior surface and a threaded engagement portion for threadably engaging a corresponding series of pipe threads adjacent the pipe end. The annular connector may be configured as either a box or pin connector depending on the configuration of the pipe end. The illustrative thread protector has a ridge that extends distally from the distal base surface. This ridge is positioned along some or all of the circumferential edge of the distal base surface. In some embodiments, the circumferential ridge may be broken into a plurality of arcuate ridge sections. The ridge has an inner surface that is oriented toward and an outer surface that is oriented away from an axis of the thread protector that is coaxial with the pipe centerline axis when the thread protector is installed. The illustrative thread protector embodiment also has a plurality of ribs extending distally from the distal base surface. These ribs are positioned and oriented so that they extend radially inward from the inner ridge surface toward the thread protector axis.

The illustrative thread protector will typically be a single integrally formed molded thermoplastic material. Any suitable material providing the requisite strength characteristics may be used. Typical polymer materials may include but are not limited to high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene, nylon, polyurethane, and acetal. High strength HDPE, polypropylene, nylon and acetal may be particularly suitable.

The circumferential ridge and the ribs serve to support and reinforce the base of the thread protector and distribute impact loads received by the thread protector when installed on a pipe. The size and configuration of the ridge and the number, size and spacing of the ribs may be varied depending on the design loads and other design criteria. In particular, these features may be determined based on an optimization between expected environmental loads and material(s) used to produce the thread protector.

Aspects of the thread protectors of the invention will now be discussed in more detail. Referring now to FIGS. 1 and 2, a thread protector 100 according to an embodiment of the invention for a pin end of a pipe is illustrated. The thread protector has a disk-shaped base 102, a proximal base surface 102a, a distal base surface 102b, and an outer edge 102c. In this embodiment, the disk-shaped base 102 is a body of revolution with circular proximal and distal base surfaces. The base 102 may be cylindrical or frusto-conical. In other embodiments, the disk-shaped base 102 may be polygonal. The base 102 is a body of revolution about a base axis 108 that is coaxial with the pipe axis when the thread protector is installed on a pipe. An annular connector portion 103 extends proximally from the proximal base surface 102a. The annular connector portion 103 has an interior connector surface 103a, an exterior connector surface 103b, and a threaded portion 103c configured to threadably engage the pipe threads of the pin end of a pipe. As will be discussed, the annular connector portion 103 may alternatively be configured for threadable engagement with a box end of a pipe as exemplified by the connector portion 203 of FIG. 3.

With reference specifically to FIG. 1, a ridge 104 extends distally to a height h from at least a portion of the distal base surface 102b of the base 102. The ridge 104 has an outer ridge surface 104a and an inner ridge surface 104b and a width w. In this embodiment, the ridge 104 is substantially circular and is co-centric with the circular outer edge 102c. In this embodiment, the width w and the height h are uniform around the ridge 104. In other embodiments, either dimension may be varied. As shown in FIG. 1, the ridge 104 may extend around the entire circumference of the distal base surface. in other embodiments, the ridge may be broken into arcuate segments.

The thread protector 100 has a plurality of ribs 106 extending distally from the distal base surface 102b and radially inward from the ridge 104 toward the base axis 108. The ribs 106 may be evenly spaced with respect to each other as shown or may have variable spacing.

The base 102, the ridge 104, the ribs 106, and the annular connector portion 103 may collectively or individually be formed from any suitable material including composite resins, thermoplastics, polymer alloys, steel, or similar materials. In particular embodiments, the base 102, the ridge 104, the ribs 106, and the annular connector portion 103 may be integrally formed as a single monolithic body.

The ribs 106 may be distributed around the entirety of the ridge 104 or along one or more portions of the ridge 104. As shown in FIG. 1, the ribs are distributed and evenly spaced in two distinct groups on opposing sides of the ridge 104. The specific configuration of the ribs 106 may be determined based on the loads to be experienced and/or based on tooling or manufacturing requirements. Each rib 106 has a length L and a width w₂. In this embodiment, the length L is the same for each rib. In other embodiments, the length L may be varied from rib to rib, depending on the desired impact-load bearing and distribution characteristics of the thread protector. The width w₂ may similarly be varied from rib to rib. Furthermore, in this embodiment, for each rib 106, the width w₂ is uniform along the length L of each rib. In other embodiments, the width w₂ may be greater at the end of the rib 106 that is adjacent the inner ridge surface 104b, with a gradual taper to a smaller width at the end of the rib that is closer to the base axis 108. This width w₂ may be varied based on the desired load-bearing characteristics of the thread protector. Each rib also has a height that may be the same as or different from the height h of the ridge 104.

Referring now to FIG. 3, an embodiment of a thread protector 200 configured for protecting the threads on the box end of a pipe is shown. The thread protector 200 has a disk-shaped base 202, a circumferential ridge 204 and radially oriented ribs 206 that may be substantially similar to the base 102, ridge 104 and ribs 106 of the thread protector 100. The thread protector 200 also has an annular connector portion 203 that projects proximally from the proximal base surface 202a of the base 202. The annular connector portion 203 has an interior connector surface 203a and an exterior connector surface 203b that includes a threaded portion 203c configured to threadably engage the pipe threads of the box end of a pipe.

The thread protector 200 FIG. 3 also includes an additional support feature that could be applied to either a box end protector or a pin end protector. This feature comprises a plurality of support members 207 in contact with the interior connector surface 203a and the proximal base surface 202a. The support members 207 extend proximally from the proximal base surface 202a and radially inward from the interior connector surface towards the base axis 208. The support members 207 may be equally spaced with respect to each other and may be distributed around all or a portion of the circumference of the interior connector surface. In the illustrated embodiment, the support members 207 have a curved, buttress-like shape. It will be understood, however, that the shape of the support members may be varied depending on the desired load bearing characteristics and the material used to form the thread protector.

Again, the base 202, the ridge 204, the ribs 206, and the annular connector portion 203 may collectively or individually be formed from any suitable material. In particular embodiments, the base 202, ridge 204, ribs 206, and connector portion 203 are integrally formed from a thermoplastic material into a single monolithic body.

Referring now to FIGS. 4 and 5, a thread protector 300 according to another illustrative embodiment is shown. The thread protector 300 has a disk-shaped base 302, a circumferential ridge 304, radially oriented ribs 306, connector portion 303 and support members 307 that may be substantially similar to those of the previous embodiments. The thread protector 300 also has a number of additional features that may be added individually or collectively to the previously described embodiments. One such feature is a center hole 312 through the base 302, which is configured for receiving an engagement portion of a tool that may be used to assist in handling or installing the thread protector 300. An annular hole extension member 310 has a center bore matching and aligned with the center hole 312 and extends proximally from the base 302. The annular extension member 310 has an inner extension wall 310a and an outer extension wall 310b. The center cylindrical hole 312 is positioned coaxially with the base axis 308 so that a cylindrical tool portion can be inserted therein and the tool simultaneously rotated about the axis of the thread protector 300 and the axis of a pipe to which the thread protector 300 is to be mounted. The thread protector 300 may have, in addition to or instead of the center hole 312, one or more off-center holes 311 through the distal base surface 302b. These additional holes 311 may extend through a portion of or all the way through the thickness of the base 302 and may be configured for receiving engagement members of a tool for that may be used to assist in handling or installing the thread protector 300. In a particular embodiment, the thread protector 300 has both the center hole 312 and two or more off-center holes 311, which are collectively configured for receiving rotation members of a tool designed to engage the thread protector, position it at the end of a pipe and rotate it to thread it onto the pipe.

Another optional feature of the thread protector 300 is the provision of one or more tool engagement slots 314 in the circumferential ridge 304. These slots 314 may be provided and configured for application of a rotational force on the thread protector 300 to install or remove the thread protector 300 from a pipe. In particular, these slots may be configured so that, in the field, any of a variety of tools not specifically designed for use in conjunction with the thread protectors of the invention may be used to provide torque to install or remove them.

In a particular embodiment, the ridge 304 of the thread protector 300 is bisected by a pair of tool engagement slots 314. The tool engagement slots 214 are positioned on a diameter through the base axis 208 on opposing sides of the ridge 204 to allow for the insertion of a bar or other tool found in a typical oil field environment. To facilitate the ability to torque the thread protector by placement of a tool member in the tool-receiving slots 314, the height h₁ of the ridge 304 may be increased adjacent the tool-receiving slots 314 to h₂. This serves to increase the bearing surface and the strength of the ridge 304 in these locations.

It will be understood that any of the above optional features may be applied to any of the embodiments described herein. Any of the embodiments described herein may be produced as a single integrally formed monolithic structure. In particular, any embodiment may be formed by molding of a thermoplastic material. Features such as threads, holes and slots may be formed by molding or by machining of the molded part.

It will also be understood that the thread protectors of the invention may be scaled to any size as required for the protection of various pipe diameters and thicknesses. The specific configuration and features of the thread protectors may be driven by the loads expected in use and desired manufactured economies.

As has been discussed, the protection devices of the present invention may be formed from any suitable material. Particularly suitable materials include various thermoplastic materials such as HDPE, LDPE, polypropylene, nylon, polyurethane, and acetal. Such materials may be provided with any of various additives selected to enhance processing characteristics or to tailor the physical characteristics of the final protector device. Physical characteristics that may be tailored include material stability, coefficient of thermal expansion (CTE), strength and stiffness, and toughness. In some exemplary embodiments, an inorganic, halloysite-based, polymer additive marketed by Applied Minerals Inc. under the name Dragonite™ is added to an HDPE and molded to form thread protector devices of the invention. In exemplary embodiments, LDPE. Filler materials or foaming agents may also be incorporated in some or all of the device components.

Exemplary thread protectors have been produced for a variety of pipe sizes using HDPE. These protectors have been shown to withstand the axial and angled load requirements of API 5CT/ISO 11960 Annex I under test conditions ranging from −50° F. to 150° F. with no damage to the pipe to which they were attached. Thread protectors successfully met these impact standards for pipe diameters ranging from 2.375 to 13.375 in.

It will be apparent to those skilled in the art that various modifications and variations can be made in the method, manufacture, configuration, and/or use of the present invention without departing from the scope or spirit of the invention.

Claims

1. A device for protecting a portion of a pipe having a pipe end, a pipe axis and a series of pipe threads adjacent the pipe end, the device comprising:

a disk-shaped base having a proximal base surface that faces the pipe end when the device is installed on the pipe and a distal base surface, the base being a body of revolution about a base axis that is coaxial with the pipe axis when the device is installed on the pipe;

an annular connector extending proximally from the base, the annular connector having an interior connector surface and an exterior connector surface and a threaded engagement portion configured for threadably engaging the series of pipe threads for securing the device to the pipe;

a ridge extending distally from at least a portion of an outer edge of the distal base surface, the ridge having a ridge height, an outer ridge surface and an inner ridge surface; and

a plurality of ribs extending distally from the distal base surface and radially inward toward the base axis from the inner ridge surface.

2. A device according to claim 1 wherein the threaded engagement portion is a part of the exterior connector surface for threadable engagement with a box end of the pipe.

3. A device according to claim 1 further comprising:

a plurality of support members extending proximally from the proximal base surface and radially inward toward the base axis from the interior connector surface.

4. A device according to claim 1 further comprising:

means for receiving an engagement portion of a tool configured for threading the device onto the pipe end.

5. A device according to claim 1 further comprising:

a plurality of cylindrical holes through the distal base surface, said holes configured for receiving an engagement portion of a tool configured for threading the device onto or removing the device from the pipe end.

6. A device according to claim 5 wherein the base has a base thickness and at least one of the plurality of holes through the distal base surface extends through less than the base thickness.

7. A device according to claim 5 wherein one of the plurality of holes through the distal base surface is coaxial with the base axis.

8. A device according to claim 7 further comprising an annular hole extension member extending proximally from the proximal base surface, the annular extension wall having an interior aligned with and in communication with the one of the plurality of holes that is coaxial with the base axis.

9. A device according to claim 1 further comprising:

a pair of tool engagement slots in the ridge, the pair of tool engagement slots being positioned on a diameter through the base axis on opposing sides of the ridge.

10. A device according to claim 9 wherein the ridge height is greater in areas adjacent the tool engagement slots.

11. A device according to claim 1 wherein each rib has a rib height that is the same as the ridge height where the rib extends radially inward from the ridge.

12. A device according to claim 1 wherein said base, said annular connector, said ridge, and said ribs are a single integrally formed body.

13. A device according to claim 12 where in the integrally formed body is formed from a thermoplastic material.

14. A device according to claim 13 wherein the thermoplastic material is selected from the group consisting of high-density polyethylene, polypropylene, nylon, and acetal.

15. A device according to claim 13 wherein the thermoplastic material includes at least one polymer additive.

16. A device according to claim 1, wherein said device meets the impact loading requirements of API 5CT Annex I at temperatures ranging from −50° F. to 150° F.