Note: Descriptions are shown in the official language in which they were submitted.
CA 02775502 2012-04-30
HIGH STRENGTH PIPE THREAD PROTECTOR
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Application No.
61/552,783 filed
October 28, 2011, which is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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
[0006] 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
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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
[0007] 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:
[0008] Figure 1 is a top view of a protection
device according to an embodiment of the
invention;
[0009] Figure 2 is a section view of a
protection device according to an embodiment of the
invention;
[0010] Figure 3 is a section view of a
protection device according to an embodiment of the
invention;
[0011] Figure 4 is a top view of a protection
device according to an embodiment of the
invention; and
[0012] Figure 5 is a section view of a
protection device according to an embodiment of the
invention;
DETAILED DESCRIPTION OF THE INVENTION
[0013] 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.
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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.
[00141 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.
[0015] 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
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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.
[0016] 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.
[0017] 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.
[0018] 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
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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.
[0019] 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.
[0020] 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.
[0021] 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.
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[0022] 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.
[0023] 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.
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[0024] 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.
[00251 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.
[0026] 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
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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. .
[0027] 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.
100281 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 14 of the ridge
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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.
[0029] 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.
[0030] 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.
[0031] 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 DragoniteTM
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.
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[0032] 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.
[0033] 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.
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