Pipeline systems

A cable entry or exit pipe is formed on a fluid transportation pipeline while in normal operation full of and transporting a fluid under a positive pressure, by a method which comprises the steps: (a) producing two semi-cylindrical shells, one of which carries an oblique branch pipe and has an aperture aligned with the bore of the branch pipe; (b) securing in a fluid tight manner around the pipeline the two shells so as to form a reinforcing collar carrying an oblique branch pipe lying at an acute angle suitable for the entry into and exit from the pipeline of a cable; (c) securing in a fluid tight manner to the free end of the branch pipe an isolating valve; (d) securing in a fluid tight manner to the free side of the isolating valve a fluid tight drilling apparatus equipped with a drilling bit; (e) opening the valve and introducing the drill bit through the opened valve into the branch pipe; (f) rotating and progressively advancing the drill bit into contact with and through the wall of the pipeline section; (g) withdrawing the drill bit and closing the valve; and (h) removing the drilling apparatus. Preferably, a liner inserted into the branch pipe between steps (g) and (h) serves as a cable guide.

This invention relates to fluid transportation pipeline systems for 
transporting bulk liquids or gases over substantial distances, and to a 
means for and a method of modifying such a pipeline system whilst it is in 
normal operation, whereby to effect a permanent change in such a system. 
In our concurrently-filed, co-pending patent application titled `Pipeline 
Systems` filed in the name of Geoffrey J. Grocott and Ralph E. J. Baskett 
filed on even date herewith 07/201,691, filed June 2, 1988 there is 
disclosed the concept of, and a method of, deploying within (instead of 
alongside) a fluid transportation pipeline for transporting bulk liquids 
or gases an electrical or other cable or line for transmitting data, 
control or other signals which need to be transmitted from one location on 
a pipeline system to another such location. 
In the case of a new pipeline, suitable branch pipes for the entry and exit 
of such a cable or line can be readily provided, by design, from the 
outset, that is during the construction of the pipes from which the system 
will eventually be assembled on site. 
However, there is also a need to provide such branch pipes permanently on 
existing pipelines, even whilst they are in normal operation, full of a 
liquid or gas flowing under a high positive pressure. 
According to one aspect of the present invention, a branch pipe for 
enabling the entry or exit of a cable to or from an existing pipeline is 
provided at a preferably straight section of the pipeline, the branch pipe 
being disposed relative to the pipeline section in that case at an acute 
angle of approximately 30 degrees, and having a bore diameter which is 
substantially less than that of the pipeline. 
Preferably, such a branch pipe is secured to the pipeline section 
indirectly by means of a cylindrical reinforcing collar or sleeve which is 
itself secured in a fluid tight manner around the pipeline section. 
Preferably, such a cylindrical collar comprises two half-shells, to one of 
which the branch pipe has been secured in a fluid tight manner. In that 
case, the half-shells are secured in a fluid tight manner around the 
pipeline section, being joined longitudinally together and 
circumferentially to the pipeline section, and the bore of the branch pipe 
opens on to the external surface of the existing pipeline through an 
aperture formed in the associated half-shell. 
In order to connect the bore of the branch pipe with the bore of the 
pipeline, the present invention preferably provides in the branch pipe 
guide and support surfaces through which a rotating drill may be 
introduced for the purpose of drilling an oblique or skewed aperture 
through the wall of the pipeline section, the guide and support surfaces 
providing both guidance and sideways support for the drill during the 
course of drilling the pipeline aperture. 
According to another preferred feature of the invention, a tubular cable 
guide or liner is secured in the branch pipe with one end thereof 
protruding through the oblique aperture in the pipeline wall, which end is 
smoothly shaped for the passage therethrough, or disposition therein, of a 
said cable or line without suffering damage. 
Preferably, the cable guide is supported in the branch pipe by at least one 
of the said guide and support surfaces. 
According to a further aspect of the present invention, a preferred method 
of securing such an angled branch pipe to a pipeline section through which 
bulk fluid is being transported at a high positive pressure includes the 
following steps: 
(a) securing in a fluid tight manner around a selected pipeline section 
such a split collar carrying an angled branch pipe; 
(b) securing in a fluid tight manner to the free end of the branch pipe an 
isolating valve (preferably, of the slide valve type); 
(c) securing in a fluid tight manner to the free side of the isolating 
valve a fluid tight drilling apparatus equipped with a drilling bit; 
(d) opening the valve and introducing the drill bit through the opened 
valve into the branch pipe, preferably through guide and support surfaces 
formed in the branched pipe; 
(e) rotating and progressively advancing the drill bit into contact with 
and through the wall of the pipeline section; 
(f) withdrawing the drill bit and closing the valve; and 
(g) removing the drilling apparatus. 
Preferably, the step (g) is preceded by the following additional steps: 
(i) replacing the drill bit by a driving tool carrying temporarily thereon 
a branch pipe liner; 
(ii) opening the isolating valve and advancing the driving tool so as to 
engage the liner in said guide and support surfaces formed in the branch 
pipe; 
(iii) securing the liner in position in the branch pipe with its shaped 
nozzle properly oriented for the passage therethrough of a said cable; 
(iv) withdrawing the driving tool; and 
(v) closing the isolating valve. 
Other features of the present invention will become apparent from a reading 
of the description that follows hereafter, and of the claims appended at 
the end of that description. 
One straight pipeline section having secured thereon a branch pipe, and a 
method of providing that branch pipe, all according to the present 
invention, will now be described by way of example and with reference to 
the accompanying diagrammatic drawings.

Referring now to the drawings, a straight section of a steel pipeline 10 
carries externally thereon a cylindrical steel collar 121 comprising upper 
and lower half-shells 14, 16 which have been welded together along opposed 
longitudinal margins 18, 20 over enclosed backing strips 22, 24, and which 
have then been welded to the pipeline 10 at their respective 
circumferential margins 26, 28. 
The upper half-shell 14 has welded thereto an oblique branch pipe 30 which 
is inclined to the pipeline an an angle of approximately thirty degrees. 
The branch pipe carries a circular flange 32 at its upper, free end, and 
communicates at the lower end with an aperture 34 formed in the upper 
half-shell 14, and with an aligned aperture 36 drilled in the pipeline 
wall 38. 
The branch pipe has secured therein a cable guiding sleeve or liner 40. 
That liner defines a longitudinal cylindrical bore 42 which communicates 
at its lower end with the bore 44 of the pipeline 10. The lower end of the 
liner constitutes an obliquely shaped nozzle 46 which projects only a 
short way into the pipeline bore 44, and which has smoothly rounded 
surfaces 48 over, or against, which an electric or other cable may pass, 
or lie, without suffering damage. 
The liner is supported in position in the branch pipe by a screw-threaded 
upper portion 50 which is engaged in a screwthreaded throat 52 of the 
branch pipe 30, and is secured against rotation by a locking screw 54 
which locates in a longitudinal keyway 56 formed in the upper end of the 
liner. 
The longitudinal bore 42 of the liner opens out at its upper end from a 
circular into a square cross section, for the purpose of receiving therein 
a driving tool (not shown) of square transverse cross section. Arcuate 
gouges 58 are formed in that upper part of the liner bore, for the purpose 
of receiving temporarily spring-biased location balls (not shown) provided 
on the said driving tool. 
The liner is guided and supported near its lower end by a cylindrical 
support surface 60 formed within the branch pipe 30. 
To the branch pipe flange 32 is secured an isolating valve unit 62 
preferably of the slide valve type, by bolts 64, and to the free side of 
that valve unit is bolted a fluid sealing means 66. 
An electrical or other cable 68 is enclosed within the pipeline bore, being 
there submerged in the fluid being transported in the pipeline (from left 
to right in the FIG. 1) at a high positive pressure of the order of 1440 
pounds per square inch (approximately 99.6 bar) or more, and a flow rate 
of the order of two meters per second. 
The cable exits from the pipeline via the nozzle 46 and longitudinal bore 
42 of the liner 40, the isolating valve unit 62, and the fluid sealing 
means 66. The cable enters the pipeline at an upstream location (not 
shown) through a similar assembly of branch pipe (secured in like manner 
to the pipeline), branch pipe liner, isolating valve unit, and fluid 
sealing means, but in this case the assembly is inclined to the pipeline 
from the opposite direction, i.e. at an acute angle relative to the part 
of the pipeline that lies upstream of the branch pipe. 
To make possible the deployment of that cable in the existing pipeline 10, 
and whilst it is in normal operation transporting bulk liquid under a high 
positive pressure, a branch pipe 12, 30 is first secured externally on the 
pipeline at each of the selected upstream and downstream locations. 
This is achieved by assembling around the pipeline at each such location 
the two half-shells 14, 16 which constitute a said collar 12 with attached 
branch pipe 30. After inserting the said backing strips 22, 24 between the 
pipeline and the respective pairs of opposed longitudinal margins 18, 20 
of those half-shells, the longitudinal edges of the half-shells are welded 
together. Thereafter, the collar so formed has its two ends welded to the 
pipeline among circumferential paths 26, 28. In each case, the welds so 
made are fluid-tight welds. 
The isolating valve unit 62 is then bolted to the branch pipe flange 32, 
and to the free side of that valve unit is bolted, in a fluid tight 
manner, a fluid tight drilling machine 70 having a drill bit in position. 
That drilling machine is indicated in FIG. 1 by chain-dotted lines. 
With the isolating valve in the open condition, the drill bit is advanced 
into the bore of the branch pipe 30, through the cylindrical support 
surface 60 and into contact with the outer surface of the pipeline 10. 
With the drill bit rotating, it is advanced still further so as to cut an 
oblique aperture 36 in the pipeline wall. 
The drill bit is then retracted into the drilling machine, the valve is 
shut, and the drill bit is replaced by a said driving tool carrying on its 
square free end a branch pipe liner 40. The liner is located axially on 
the driving tool by spring-loaded balls which engage in the arcuate gouges 
58 formed in the liner bore. 
The isolating valve 62 is opened, and the liner 40 advanced into the branch 
pipe so as to bring the screw-threaded portion 50 thereof into engagement 
with the screw-threaded throat 52 of the branch pipe bore, whereupon the 
liner is rotated to screw it firmly into its working position in the 
branch pipe, with the nozzle thereof projecting a short way into the 
pipeline bore 44. 
The driving tool is then withdrawn from the end of the liner (against the 
resistance offered by the spring-loaded balls), and from the isolating 
valve unit, whereupon the isolating valve is closed, and the drilling 
machine removed. 
The fluid sealing means 66 is then secured to the isolating valve unit in 
place of the drilling machine, and a cable 68 is deployed in the pipeline 
in the manner described in the afore-mentioned co-pending patent 
application, to which the reader's attention is hereby directed for 
further information concerning the method of deployment of the cable. 
The screw-threaded engagement of the liner in its socket 52 enables the 
subsequent removal of the liner from the branch pipe at any time, in the 
event, for example, that it is necessary to seal the branch pipe 
temporarily by means of a screw-threaded sealing plug (inserted in place 
of the liner) as a preliminary to removing the slide valve for replacement 
or repair. 
In such a case, the cable would be removed from the pipeline first so as to 
enable the slide valve to be closed temporarily as a preliminary to the 
withdrawal of the liner. 
If desired, the screw-threaded portion 50 of the liner 40 may be shortened, 
so as to permit the use in association with such a shortened liner of a 
screwed annular retention plug. Such a modified construction would permit 
the temporary sealing of the branch pipe without the need to remove the 
liner itself, since the temporary screwed sealing plug could be inserted 
in place of the annular retention plug alone. 
Alternatively and more advantageously, the liner 40 may be shortened by 
omitting the screw-threaded portion 50, and be provided instead with a 
radial flange for effecting axial location of the liner in the branch 
pipe, and an axial keyway for effecting rotational location in the branch 
pipe. In that case, the liner would be secured against axial movement by 
an annular retention plug screwed into the screw-threaded throat 52 of the 
branch pipe. Such an arrangement has the two advantages: (a) that the 
liner 40 once inserted need never be removed, and (b) that it ensures 
correct and easy positioning of the obliquely-shaped nozzle end 46 of the 
liner relative to the bore 44 of the pipeline into which it protrudes. 
For a pipeline having a nominal bore of approximately 8 inches (203 mm) 
diameter, the branch pipe has had an internal diameter of approximately 2 
inches (51 mm). 
The branch pipes, and method of securing them to a pipeline, described 
above make it possible to deploy a cable or other line in an existing 
pipeline whilst it is in normal operation transporting fluid under a high 
operating pressure, and with the minimum of difficulty. 
Whereas the branch pipe has been described as being inclined at angle of 
approximately thirty degrees to the pipeline, any other angle of 
inclination may be selected instead, provided that it will ensure for a 
cable to be deployed in the pipeline a smooth passage into/out of the 
pipeline, and at the same time not present any insuperable difficulties in 
constructing and securing the branch pipe and drilling the aperture in the 
pipeline wall. 
Whereas, it is preferred to provide around the pipeline section 10 the 
reinforcing collar 12 (14,16) for carrying the branch pipe 30, that collar 
may be omitted and the branch pipe secured directly to the pipeline 
section. 
If desired, additional guide and support surfaces may be provided for 
supporting and guiding the drill bit and the liner 40.