Method and device for forming a branch connection in a pipe

In a method of forming a branch connection in a fluid carrying pipe (3) by attaching to the pipe (3) a saddle unit (1) incorporating a cutting member (11) capable of being operated to cut a hole in the pipe wall, the cut is effected so that it extends only partly around the circumference of a circle so as to form a tongue (18), and the tongue is bent into the pipe while remaining connected to the adjoining part of the pipe wall.

This invention relates to a method of and a device for forming branch 
connections in fluid carrying pipes, more especially, though not 
exclusively, domestic water pipes. 
One method of forming a branch connection in such a pipe involves shutting 
off the water supply and draining the system, drilling a hole in the wall 
of the pipe, and clamping a saddle unit to the pipe over the hole so 
formed with a resilient gasket interposed between the surfaces of the 
saddle unit and pipe to form a fluid-tight seal, the saddle unit being 
provided with means for connecting a branch pipe thereto, and having a 
passage for the flow of water between the hole in the main pipe and the 
branch pipe. 
However it is not always convenient or desirable to cut off the water or 
drain the system and in an alternative method which has been proposed the 
saddle unit is itself provided with a cutting member which can be 
operated, once the unit has been clamped to an undrilled pipe, to cut a 
circular hole in the wall of the pipe for the passage of water from the 
pipe to the branch connection; such a method as carried out hitherto, 
whilst it can be carried out without cutting off the water supply, also 
suffers from a drawback in that the circular slug cut from the wall of the 
pipe is deposited within the interior of the pipe, and could in some cases 
be carried into a position in which it seriously interferes with the flow 
of water. 
An object of the present invention is to provide a method and apparatus for 
forming a branch connection in a pipe which avoids the above 
disadvantages, and whilst it is mainly concerned with the formation of 
branch connections in domestic water pipes it could also have other 
applications. 
According to one aspect of the invention, in a method of forming a branch 
connection in a fluid carrying pipe by attaching to the pipe a saddle unit 
incorporating a cutting member capable of being operated to cut into the 
pipe wall, the cut is effected so that it extends only partly around the 
circumference of a circle so as to form a tongue, and the tongue is bent 
into the pipe whilst remaining connected to the adjoining part of the pipe 
wall. 
Preferably the cutting member is simultaneously rotated and driven inwards 
through the pipe wall, with its cutting edge or edges spaced from its axis 
of rotation, and is prevented from cutting a completely circular hole in 
the pipe wall, either by initially forming a depression in the part of the 
pipe wall traversed by the cutting edge or edges or by offsetting the axis 
of rotation of the cutting member from the axis of the pipe. By this means 
a web of material is left when the remaining part-circular section of the 
wall is cut through and continued inward movement of the cutting member 
urges the tongue so formed into the pipe. 
The invention has the advantage that the connection can be formed 
automatically on attachment of the saddle unit to the pipe, without the 
need for cutting off the water supply, and without a loose slug of metal 
passing into the interior of the pipe. 
The saddle unit can have any convenient construction capable of being 
secured to the pipe to which the branch connection is to be made and such 
that a fluid-tight seal can be formed between the adjacent pipe and saddle 
unit surfaces, with or without the need for an intervening gasket. 
The invention also relates to devices for carrying out such a method. 
According, therefore, to another aspect of the invention, a device for 
forming a branch connection in a pipe comprises a saddle unit having a 
fluid passage in it and arranged to be secured to the surface of the pipe 
with an end of said passage closed by said pipe surface when the unit is 
attached thereto, sealing means for forming a fluid-tight seal between the 
surface of the pipe and the adjacent surface of the unit around said end 
of the passage, a cutting member capable of rotation about an axis 
transverse to the pipe and of simultaneous movement inwards towards the 
pipe axis for progressively cutting through the wall of the pipe around a 
circular path, with a relatively small part of the wall around said path 
spaced further from the cutting edge of the tool than the remainder such 
that operation of the cutting tool results in the formation of a 
part-circular tongue joined to the remainder of the pipe wall by a 
narrower web, and such that further movement of the cutting tool depresses 
the tongue inwards while leaving it attached to the pipe wall by said web. 
Preferably the device includes a backing member securable to the saddle 
unit by means of screws, bolts or the like such that the pipe can be 
clamped between them. Both the saddle unit and backing member are 
conveniently formed of a relatively rigid moulded plastics material. 
Alternatively, die-cast components may be used. 
The backing member may comprise a bracket securable to a wall or other 
support, the bracket and saddle unit preferably being formed with 
semi-cylindrical grooves for accommodating the pipe. 
The saddle unit may incorporate a spigot within said groove such that when 
the unit is clamped to the pipe it forms a depression in the pipe wall 
under the path of the cutting edge or edges of the cutting member, the 
depression preferably being disposed under part of the path near to the 
side of the pipe. The spigot in such a case can be formed of any 
convenient material carried by the saddle unit, although where the latter 
is formed of a suitable material it may be provided by a projection 
integral with the unit. 
Preferably, however, the cutting member is disposed with its axis of 
rotation offset from the axis of the pipe. 
In each case the cutting through of the pipe wall leaves a narrow web 
within the depression on the one hand, and at the side of the pipe towards 
which the cutting tool is offset on the other hand, unsevered, and this 
allows the tongue of metal subsequently to be pressed into the pipe 
without being parted completely from the pipe. 
The saddle unit may incorporate a manually adjustable valve for controlling 
the flow of fluid from the pipe into the branch connection in use, the 
valve body in such a case preferably being securable to the saddle unit by 
screw threads, and the valve body carrying the cutting member such that as 
it is screwed into the saddle unit it produces the rotational and inward 
movement of the cutting member.

Referring first to FIGS. 1 to 4, the 35 device illustrated therein 
comprises a saddle unit 1 and a bracket member 2 each formed with a 
semi-circular groove appropriate to the dimensions of the pipe 3 to which 
the branch connection is to be made, and arranged to be clamped to each 
other around the required region of the pipe by means of a pair of screws 
4, a gasket 5 of rubber or other suitable resilient material being 
provided between the surface of the pipe and the groove in the saddle to 
form a fluid-tight seal between them. 
The saddle unit 1 is formed with a passage which extends radially with 
respect to the pipe axis, the inner and outer ends of the passage being of 
smaller and larger diameter respectively, the outer end 8 being internally 
threaded, and carrying an externally threaded valve unit 9. This carries 
coaxially at its inner end a hardened steel tubular cutting member 11 
which projects into the narrower part 7 of the passage, and whose cutting 
end can be caused to extend through the passage and engage and 
progressively cut through the wall of the pipe as the valve body 9 is 
screwed into the saddle unit. 
In use, the bracket member 2 is first attached to a wall or other support 
by means of screws (not shown) passing through holes 12 in the bracket, in 
order to provide a firm foundation for the pipe 3, a packing piece being 
utilised if necessary in order to ensure that the pipe seats centrally in 
the groove. 
The saddle unit 1 is then secured to the bracket 2, with the valve and 
cutter assembly retracted as in FIG. 1, by the tightening of the screws 4 
into captive nuts 13. During this process a relatively narrow, hardened 
metal projection 14 located within the groove of the saddle unit 1 to one 
side of the passage 7 engages the wall of the pipe 3 and forms a 
depression as at 15 (FIG. 2) as the screws 4 are tightened. 
The valve unit 9 is then screwed firmly into the saddle unit 1, during 
which process the resultant rotation and simultaneous inward movement of 
the cutter 11 causes it to cut through the pipe wall. Because of the 
depression 15 formed in the pipe 3 by the projection 14 the cutter does 
not initially make contact with the pipe wall at this position and 
accordingly, although it makes an almost completely circular cut in the 
position as indicated by the broken line 16 in FIG. 4 and the enlarged 
view of the pipe in FIG. 4A, it leaves a narrow web 17 uncut. Further 
screwing-in of the valve unit 9 causes the almost circular tongue 18 
formed by the cutter to be bent inwards as shown in FIG. 3 but it still 
remains joined to the remainder of the pipe by the web 17. The tongue 18 
protrudes into the pipe 3 without significantly interfering with the water 
flow, and the introduction of a loose slug of metal into the pipe is 
avoided. A compressible washer 20 ensures an adequate fluid seal between 
the valve unit 9 and the saddle unit 1 before the penetration of the pipe 
wall by the cutting tool 11. 
A locknut 28 is provided in the main threaded stem of the valve unit to 
lock it in a required position relative to the saddle unit following the 
penetration of the pipe 3. 
The valve unit 9, which can have any convenient construction, is shown 
provided with a threaded outlet 19 to which a branch pipe may be coupled, 
and a manually operable control knob 21 which can be rotated in known 
manner to adjust the position of the valve washer 22 relative to its 
seating 23. 
The second device illustrated in FIGS. 5 and 6 is similar to that described 
with reference to FIGS. 1 to 4, except that the projection 14 is omitted, 
and instead of the passages 7, 8 in the valve unit 9 being disposed with 
its axis 24 cutting the pipe axis 25 it is offset therefrom by a small 
distance 26 (FIG. 5). 
Then in use when the valve unit 9 is screwed into the saddle unit 1 causing 
the tubular cutting tool 11 to cut into the pipe, it again cuts only a 
part of a complete circle to leave a tongue 18 joined to the remainder of 
the pipe wall by a narrow web 17 (see also FIG. 6A). Further screwing-in 
of the valve unit 9 causes the cutting tool to depress the tongue 18 so 
formed into the pipe without severing it from the pipe as in the 
embodiment previously described. 
Although in each of the embodiments described the device incorporates a 
manual control valve for controlling the flow of water from the main pipe 
3 to a branch pipe, it will be understood that the invention may be 
utilised to form branch connections which do not require such valves. 
Moreover apart from forming branch connections in domestic water pipes it 
can be utilised for forming connections in other pipes capable of being 
penetrated by a rotating cutter, where it is undesirable to cut-off the 
supply of fluid within the pipes when making the connection. 
Whilst the cutter 11 in both embodiments has been shown as cylindrical its 
cutting end could, in some cases be slightly tapered, as this could 
facilitate the depression of the formed tongue 18 by the cutter.