Tubing protector

A device for protecting and securing small diameter tubular members along a pipe string in a wellbore is disclosed. The protector is designed to fit about the joints of connecting pipe sections and comprises a sleeve assembly capable of being arranged and locked about a pipe joint. The sleeve assembly preferably comprises a plurality of symmetrical, most preferably semi-cylindrical, sleeve members having interfitting longitudinal end portions, preferably held by hinge pins in circular arrangement about a pipe joint. At least one longitudinal channel is formed, preferably with a pair of parallel, longitudinal ridges on the interior surface of the sleeve assembly to receive and hold therein a small diameter tubular member. The sleeve assembly is further characterized by shoulder members spaced sufficiently far apart to bracket the greater diameter pipe joint to prevent longitudinal displacement of the sleeve assembly with relation to the pipe string and joint. Preferably, the channel includes a biasing device, most preferably a resilient or elastomeric material, to bias the tubular member against the pipe joint to prevent longitudinal and transverse movement relative thereto. Preferably, the ends of the sleeve members are formed to project inwardly, most preferably at 45 degrees, to provide both annular shoulder members and a smoother transition between the end of the sleeve assembly and the adjacent pipe section to prevent hanging in the borehole.

BACKGROUND OF THE INVENTION 
This invention pertains to a tubing protector and more particularly to an 
apparatus for protecting small diameter tubular members secured along the 
outside of the joints in a pipe string to be used in a borehole. 
It is often desirable to pass a small diameter tubing, capillary conduit, 
wire or the like (hereinafter collectively referred to as "tubular 
member") into a borehole to provide communication between the surface and 
the bottom of the borehole. For example, it may be useful to communicate 
downhole pressure data to the surface by transmitting the fluid pressure 
via a small diameter capillary tubing. Such a system is illustrated in 
U.S. Pat. No. 3,895,527. 
Capillary tubing systems were initially developed for surface recording of 
bottom hole pressures. Typically, these systems were used in wells up to 
ten thousand feed deep and on land rather than offshore, where holes, 
while not straight, do not have extreme deviations. 
Capillary tubing systems have also been used for the transportation of 
chemicals to wellbore bottoms to treat the fluids and/or formation from 
which such fluids are being produced. Chemical injection has been used to 
control corrosion in wells by continuous injection of a chemical 
inhibitor. The advantages gained by applying the continuous injection 
procedure in oil and gas wells is well known and many procedures and 
equipment configurations have been field tested. The two methods most 
widely used are kill string tubing and the injection of inhibitor packer 
fluid through a bottom hole valve providing a port between the casing 
annulus and tubing. 
While capillary systems have not been used for the transmission of 
inhibitors or used in deep, highly deviated holes, they have been 
successfully used both pneumatically for surface recording of bottom hole 
pressures and hydraulically for injection of single component, low 
viscosity liquids in straight holes at relatively shallow depths. 
In relatively straight holes, standard types of tubing protectors can be 
modified for positioning and protecting the tubular member. However, 
standard protectors are not suitable for use in deep, high angle, high 
temperature wells. 
The foregoing background information is set forth in greater detail in a 
paper entitled, "Corrosion Protection By Downhole Continuous Inhibitor 
Transmission Via External Capillary," Paper No. 268 presented at Chicago, 
Ill. to the National Association of Corrosion Engineers on Mar. 3-7, 1980. 
When the above-described tubular communication is used in a borehole, the 
small diameter tubular member is typically passed along the outside of the 
pipe string and attached thereto as the tubing or pipe string is 
introduced into the borehole as illustrated in U.S. Pat. No. 3,757,387. 
The pipe string is normally comprised of pipe sections which are coupled 
together with threaded connectors formed integrally on each end of the 
pipe sections to form a pipe joint. These pipe joints typically are of a 
greater diameter than the remaining portions of the pipe string. When 
small diameter tubing is passed along the pipe string, it must necessarily 
pass over each pipe joint. 
As the pipe is introduced into the borehole, the large diameter joints tend 
to press the small diameter tubing against the wall of the borehole 
causing wear and damage to the tubular member. Performation or rupture may 
also result from twisting of an unsecured and unprotected tubular member 
as the drill string turns, particularly at a pipe joint where the tubular 
member may be pressed against the borehole wall. Additionally, an 
unsecured tubular member, as a result of its length and weight, may 
stretch and thereby deform its interior bore. Such stretching may also 
cause the tubular member to rupture. Therefore, it is desirable to provide 
a tubing protector capable of protecting and securing the tubular member 
at the pipe joints. 
In order to provide a fit that will not slip on the pipe and which will 
hold the tubular member in place, it is necessary to utilize a protector 
that will fit the dimensions of the pipe joint. There are many types and 
sizes of pipe joints. Accordingly, tubing protectors in a large variety of 
sizes are required. The manufacture and cost of this variety of tubing 
protectors has been a major problem. Therefore, it is desirable to provide 
a protector capable of being easily and inexpensively manufactured in a 
wide variety of sizes. 
Additionally, protectors which are oval or have outwardly projecting 
portions tend to hang on the borehole wall. In deviated holes, when the 
protector hangs, the pipe rotates within the protector thus causing the 
tubular member to twist and distort. Accordingly, it is desirable to 
provide a protector having a circular outer surface with no outwardly 
projecting portions and a smooth transition area from pipe string to 
protector to minimize hang in the borehole. 
The above problems have created the need for a special type of tubing 
protector for use with small diameter tubular members. The present 
invention provides a new and improved tubing protector device which will 
not slip on the pipe, which will prevent wear and damage to a tubular 
member passing along the outside of a pipe string, which closely fits the 
dimension of the pipe joint connection, which performs satisfactorily in a 
highly deviated borehole and which is easily and inexpensively 
manufactured in a variety of sizes. 
SUMMARY OF THE INVENTION 
The tubing protector of the present invention overcomes the foregoing 
disadvantages and provides an easily and inexpensively manufactured 
apparatus for protecting the passage of small diameter tubular members 
along a pipe joint in a pipe string. The present invention includes a 
sleeve assembly capable of being arranged and locked about a joint between 
pipe sections. The sleeve assembly is characterized by one or more means 
on the inner surface thereof for receiving and holding the small diameter 
tubular members in a fixed relation to the pipe string and joint. The 
sleeve assembly is further characterized by means for preventing 
longitudinal displacement thereof with relation to the pipe joint. 
The sleeve assembly preferably comprises a plurality of separable sleeve 
members capable of being arranged and locked, generally with interfitting 
hinge means, about a pipe joint to form a sleeve assembly. Most 
preferably, the separable sleeve members are semi-cylindrical with 
interfitting male and female hinge means located along both longitudinal 
edges to produce a cylindrical sleeve assembly having a circular cross 
section. 
Means for receiving and holding the same diameter tubular members are 
preferably provided by one or more longitudinal channels formed on the 
inner surface of the sleeve assembly. In a preferred embodiment, each 
channel is formed between embossed, longitudinal, parallel ridges. Another 
feature of the invention includes the use of biasing means, preferably, a 
resilient or elastomeric biasing material, within the longitudinal 
channels for biasing the small diameter tubular member against the pipe 
joint to prevent longitudinal and transverse movement of the tubular 
member relative to the joint. 
Another feature of the present invention is a means for preventing 
longitudinal displacement of the sleeve assembly with relation to a pipe 
joint. This means is provided by a plurality of inwardly projecting 
shoulder members formed on at least some of the sleeve members. An 
adjacent pair of shoulder members on each sleeve member is formed 
sufficiently far apart longitudinally along the sleeve member to bracket 
the greater diameter pipe joint when the sleeve assembly is placed about 
that joint. Most preferably, the displacement prevention means is provided 
by a pair of inwardly projecting annular shoulder members, one located at 
each end of the cylindrical sleeve assembly. 
A further feature of the present invention includes the formation of the 
sleeve assembly ends or annular shoulder members thereon with radially 
inwardly projecting outer surfaces, preferably at approximately 45 degrees 
to the side wall of the sleeve assembly, to provide a smooth transition 
between the pipe string and protector to help prevent hang in the 
borehole. 
The tubing protector of the present invention has many advantages. It is 
easily manufactured and used. It provides a device for reliably and 
securely receiving, retaining, and protecting small diameter tubular 
members about a pipe joint. The present invention provides a device 
capable of performing these functions at a pipe joint and of being secured 
from relative longitudinal movement therewith. The protectors of the 
present invention, having been run in holes with deviations as high as 50 
degrees from vertical with excellent results, would be ideal for any 
deviated hole. These and other meritorious features and advantages of the 
present invention will be more fully appreciated from the following 
detailed description and claims.

While the invention will be described in connection with the preferred 
embodiment, it will be understood that it is not intended to limit the 
invention to that embodiment. On the contrary, it is intended to cover all 
alternatives, modifications and equivalents as may be included within the 
spirit of the invention as defined in the appended claims. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring first to FIGS. 1, 3 and 5 of the drawings, a section of pipe 11 
is shown having pipe joint 12 extending through a protector or sleeve 
assembly 16 capable of being arranged and locked about a connection 
between pipe sections, the joint 12 having a diameter greater than that of 
the pipe sections. 
The protector is preferably comprised of a plurality of sleeve members 18, 
more preferably symmetrical sleeve members, and most preferably 
semi-cylindrical sleeve members, each member having hinge means 20 formed 
along its longitudinal edges. However, in an alternative embodiment (not 
illustrated), sleeve assembly 16 may be comprised of a single sleeve 
member 18 having hinge means 20 along a single pair of interfitting 
longitudinal edges and being sufficiently flexible to permit installation 
about pipe 11 and joint 12. 
Hinge means 20 is preferably comprised of interfitting alternate male and 
female edge portions, respectively 22 and 23. The male portions 22 have 
rolled over segments 21 on their end edges. See FIGS. 2 and 3. Male 
portions 22 interfit with female portions 23 on the abutting longitudinal 
edges of sleeve members 18. The rolled over segments 21 form a 
longitudinal circular channel 24 which is arranged to receive hinge pin 26 
extending through interfitting male portions 22 to hold sleeve members 18 
in assembly about a pipe joint 12. Although this hinge means is preferred 
because of its simplicity, those skilled in the art will know of many 
hinge means which may be used. For example, other hinge means may employ 
tapered hinge pins. 
At least one sleeve member 18 includes on its inner surface one or more 
means for receiving and holding the small diameter tubular members 34 in a 
fixed relation to the pipe string. In a preferred embodiment, the exterior 
walls of sleeve members 18 are embossed, preferably midway between their 
longitudinal edges to form parallel, longitudinal, concave ridges 28. In 
another feature of the present invention, concave ridges 28 are 
interrupted with strengthening means along their length to improve the 
longitudinal bending properties of sleeve members 18. The strengthening 
means include braces 30 and the like. 
In a preferred embodiment, concave channel 32 (FIG. 3) formed between 
embossed ridges 28 on the inner surface of sleeve member 18 provides the 
means for receiving and holding the small diameter tubular members 34 in a 
fixed relation to the pipe string. Channel 32 is uninterrupted throughout 
its length and serves as a protective groove in which a small diameter 
tubular member 34 such as a capillary tubing, may be housed. Channel 32 
preferably extends as far as practical along the longitudinal length of 
sleeve member 18. One or more channels 32 may be formed in each sleeve 
member 18. Preferably, each member 18 includes one channel 32 formed 
midway between the longitudinal edges of member 18. 
Preferably, the ridges and hinges are arranged so that they form 
symmetrical contact points about the circumference of pipe joint 12 when 
sleeve members 18 are assembled on pipe 11. These contact points serve as 
spacers to maintain the preferred circular configuration of sleeve 
assembly 16 when assembled on pipe 11 about joint 12 and also serve as 
fulcrum points when sleeve members 18 are compressed about pipe joint 12 
to facilitate assembly thereon. 
Sleeve assembly 16 further comprises a means for preventing longitudinal 
displacement of the protector with relation to pipe joint 12. This means 
comprises a plurality of inwardly projecting shoulder members 36 formed on 
at least some of sleeve members 18. An adjacent pair of shoulder members 
36 on each sleeve member 18 is formed sufficiently far apart 
longitudinally along sleeve member 18 to bracket the greater diameter 
joint 12 of pipe 11 when sleeve assembly 16 is placed about the joint. In 
a preferred embodiment, this means is provided by a pair of annular 
shoulder members 36 formed at each end of cylindrical sleeve assembly 16. 
Shoulder members 36 must project inwardly at least within the 
circumference of joint 12. 
In a presently preferred embodiment, shoulder members 36 extend inwardly 
from the ends of sleeve assembly 16, most preferably at an angle of 
approximately 45 degrees from the outer wall of the sleeve assembly as 
shown at 37, to provide a smooth transition region between the protector 
and the pipe string by forming a smooth radius at 38. This configuration 
minimizes or eliminates the hanging up of the protector on the sides of 
the borehole. 
Most preferably, shoulder members 36 are spaced slightly from or in contact 
with pipe joint 12 along cylindrical pipe wall 41 adjacent the conical 
transition region 42. Shoulder members 36 include stops or tabs 51 
projecting radially inwardly from the inner surface of sleeve members 18. 
The inside surfaces of stops 51 are spaced slightly from cylindrical outer 
wall 41 of pipe 11. Movement of sleeve assembly 18 along the axis of pipe 
11 brings the inner edges of tabs 51 into contact with conical transition 
region 42., directing a portion of the force of abutment therebetween into 
a radially outward component. Sleeve assembly 16 has its strongest 
resistance to deformation in this direction, enhancing the resistance of 
the protector to longitudinal movement. 
Another type of pipe joint, an API external upset joint, is illustrated in 
FIG. 6. The API external upset joint has a more accentuated shoulder 46 
formed on outer portion 48 of the pipe joint. With this joint, stops or 
tabs 51 contact shoulder 46 directly to prevent longitudinal and axial 
movement of the protector with relation to the pipe joint. 
Sleeve assembly 16 further includes in a presently preferred embodiment a 
means within channel 32 for biasing tubular member 34 against joint 12 to 
prevent longitudinal and transverse movement relative thereto. Referring 
now to FIGS. 2 and 4 of the drawings, a strip of resilient or elastomeric 
material 52 is positioned in channel 32 on the inner surface of sleeve 
member 18. In assembly with pipe 11, resilient material 52 serves to bias 
tubular member 34 against the outer wall of pipe joint 12. This biasing 
action maintains the tubing in place against pipe joint 12, preventing 
longitudinal and transverse movement of tubular member 34. The total 
weight of tubular member 34 in a deep well is substantial and may deform 
or separate the tubing if it is allowed to hang unsupported. Therefore, it 
is important to maintain both longitudinal and transverse support of 
tubular member 34. 
Referring again to FIGS. 2 and 3 of the drawings, particular attention is 
drawn to the preferred symmetrical configuration of semi-cylindrical 
sleeve member 18, which when assembled with another identical sleeve 
member provides sleeve assembly 16 for protecting tubular member 34. In a 
preferred embodiment, sleeve member 18 is formed so that male and female 
hinge portions, respectively 22 and 23, are equidistant from the center of 
channel 32 formed by ridges 28. This symmetrical configuration lends 
itself to the manufacture of sleeve members 18 of various diameters in an 
adjustable die with the edges of sleeve members 18 being dimensioned away 
from the central channel 32. Thus, the edges of the forming die are 
adjusted either laterally or longitudinally away from the center of the 
die respectively to provide for a larger diameter or a longer sleeve 
member. Due to the wide variety of pipe sizes and joint configurations 
which are used in borehole operations, this becomes an important feature 
in minimizing the cost of the protector. 
FIG. 2 illustrates the use of shorter hinges near the ends of sleeve 
members 18. The interfitting edge portions of sleeve members 18 have 
smaller lengthwise dimensions (FIGS. 1 and 2) near the ends of the sleeves 
to strengthen the sleeves against bending. This arrangement prevents a 
large female portion 23 from being positioned near and weakening the end 
of sleeve member 18. The ends of sleeve member 18 are thus strengthened 
against deformation about the corner formed by the longitudinal and end 
edges of sleeve members 18. Deformation in this area would tend to expand 
sleeve assembly 16 over pipe joint 12. 
Further, the protector is subjected to significant longitudinal forces when 
being lowered into the borehole. Shown in FIGS. 2, 3 and 5 are reinforcing 
stops or tabs 51, positioned on the inner ends of sleeve members 18 to 
contact pipe 11 when assembled thereon and focus any bending moment 
applied to the sleeve ends at a point on the interfitting edge portions 
between interfitting mating edges. The edges 53 of stops or tabs 51 and 
their abutment with pipe joint 12 become an important feature to redirect 
a portion of these forces radially. 
Tabs 51, preferably formed of metal, are attached to the inner wall of 
sleeve members 18 inward of shoulder members 36 and between the hinge 
means and embossed ridges 28. Tabs 51 direct a portion of the force of 
abutment between pipe joint 12 and sleeve assembly 16 in a radially 
outward direction where the cylindrical sleeve assembly has its strongest 
resistance to deformation. This provides greater resistance against the 
ends of the sleeve assembly 16 being peeled back over pipe joint 12 when a 
longitudinal force tries to displace the assembly along the axis of pipe 
11 and over pipe joint 12. Stops or tabs 51 are preferably arranged so 
that their inner lateral edges 53 are longitudinally aligned with a point 
between, and most preferably midway between, the lateral edges, 
respectively 55 and 56, of the second hinge portion from the ends of 
sleeve members 18. Tabs 51 tend to engage the outside of the pipe 
transition region 42 before other parts of the protector and thus, if 
relative motion occurs between pipe 11 and sleeve assembly 16, inner edges 
53 of tabs 51 tend to serve as fulcrums for any bending moment applied to 
the protector. Since inner edge 53 is aligned with a point somewhere 
between the ends 55 and 56 of the second hinge portion from the ends of 
sleeve members 18, the bending moment is not applied to the less strong 
edge portions 55 and 56 of the hinges. 
FIG. 3 illustrates another feature of the invention pertaining to the 
contact points formed by the hinges at 56 and ridges 28. These inward 
projections space the sleeves about the joint 12 when assembled to form 
and maintain a circular cross section for the outer surface of sleeve 
assembly 16. In deviated boreholes there is a tendency for the pipe to 
twist as it is run into the hole. When the protector does not have an 
outer surface with a circular cross section or when the outer surface has 
projections outside its circular surface, such projections or out of round 
surfaces tend to hang up on the wall of the borehole and cause the pipe 
string to rotate in the protector. This rotation fouls tubular member 34 
in the hole, possibly causing the tubing to deform or sever. 
The protector of the present invention is held about pipe joint 12 by an 
interference type fit, attained by using a special installation tool 
during mounting to the pipe to clamp or squeeze the protector. This level 
of interference is maintained by the retaining hinge pin configuration. 
The protector units are specifically sized to various pipe and joint sizes 
to assure the interference type make-up. Installation of the protectors is 
a simple process requiring 20 to 30 seconds per joint. 
FIG. 3 also aids in understanding assembly of sleeve members 18 about pipe 
joint 12. In the presently preferred embodiment having symmetrical, 
semi-cylindrical sleeve members 18, pin 26 is initially inserted into 
openings 24 in one of the mated edges of a pair of sleeve members 18. 
Sleeve members 18 are then hinged closed in a swinging motion about pipe 
joint 12 with shoulder members 36 arranged near the transition portion 42 
(shown in FIG. 5) of joint 12. In the most preferred embodiment, the free 
edges of sleeve members 18 will not meet of their own accord to be clamped 
about pipe 11. Therefore, a clamping force is applied simultaneously to 
the points "A" as shown in FIG. 3 along the longitudinal face of the 
sleeves with a special tool (not shown). This force compresses sleeve 
members 18 against pipe joint 12 at bearing points formed by embossed 
ridges 28 and the inner edge 56 of the hinges. This compression of sleeve 
members 18 at points "A" between the bearing points causes the 
longitudinal edges of sleeve members 18 to move in the direction of arrows 
B. Since the already hinged edges on one side of assembly 16 are fixed 
relative to one another, the free edges close toward one another. When the 
free edges have closed to the extent that openings 24 in overlapping male 
portions 22 are aligned, another pin 26 is inserted in openings 24, 
clamping sleeve assembly 16 about pipe joint 12. The force at points "A" 
is then removed and the assembly is lowered into the borehole until a 
subsequent pipe joint 12 is ready to be interconnected into the drill 
string and the procedure outlined above is repeated. 
The foregoing description of the invention has been directed in primary 
part to a particular preferred embodiment in accordance with the 
requirements of the patent statutes and for purposes of explanation and 
illustration. It will be apparent, however, to those skilled in the art 
that many modifications and changes in this specific apparatus may be made 
without departing from the scope and spirit of the invention. For example, 
hinge means employing taper, hinge pins may be substituted for the hinge 
means described and illustrated. Many means of receiving, holding and 
biasing the tubular members on the inner surface of the protector may be 
formulated by those skilled in the art. Therefore, the invention is not 
restricted to the particular form of construction illustrated and 
described, but covers all modifications which may fall within the scope of 
the following claims. 
It is Applicant'intention in the following claims to cover such 
modifications and variations as fall within the true spirit and scope of 
the invention.