Tube plug

A bore plug comprises a deformable sleeve to fit inside a bore to be plugged, two tapered members interfitting with the sleeve to engage opposite ends thereof, and an intercoupling of the tapered members actuatable to draw the latter together and deform the sleeve into circumferential engagement with the interior of the bore at or near each end of the sleeve. Provision of bored channels in one of the tapered members and the sleeve allows introduction of flowable sealing material after deformation of the sleeve.

The invention relates to tube or bore plugging and has particular, but not 
exclusive, application to isolating defective heat exchanger tubes. 
Heat exchangers are widely used in many processes and applications in the 
chemical and power supply industries. A conventional construction for heat 
exchangers may make use of a housing vessel having, or fitted with, 
flanging to which a plurality of U-shaped tubes are fitted to carry a heat 
exchanger fluid. These tubes may have to withstand substantial pressures, 
say up to 2,000 psi. Where such tubes develop leaks, whether due to 
corrosion or for other reasons, it has been a common practice to plug them 
with a wedge driven into an end of the defective tube, but with only 
moderate success. 
It is an object of the invention to provide an alternative way of plugging 
tubes or bores with an improved likelihood of success. 
According to the invention there is provided a tube or bore plug comprising 
a deformable sleeve to fit inside a tube to be plugged, two tapered 
members interfitting with the sleeve to engage opposite ends thereof, and 
an intercoupling of the tapered members whereby they are drawn together to 
deform the sleeve into circumferential engagement with the interior of the 
tube at each end of the sleeve. 
Preferably the tapered members have their tapers fit into and engage the 
internal edges of the sleeve which may be formed with an external ridge at 
or near each of its ends. Such ridges may be shaped to coact with the tube 
wall on spreading thereof by the tapers in order to assist the deformable 
sleeve to buckle inwardly at its mid region rather than outwardly. 
In one particular application an elongated member, say of tube or rod-like 
form, has a head or end that is relatively enlarged and tapered to 
constitue one of said tapered members, and a sleeve-like collar with one 
tapered end which fits over the elongated rod or tube-like member to 
constitute the other of said tapered members, the other end of the rod or 
tube-like member is adapted to cooperate in drawing the tapered members 
together, preferably by being threaded so that a nut may coact with the 
other end of the tapered sleeve or collar to draw said tapered members 
together. 
Preferably, at least after deformation of the sleeve, there will be a space 
between the sleeve and the bore, and the plug has a passageway for the 
introduction into that space of a sealing material. For a tube-like member 
cross-bores or ports may be formed at the position of the deformable 
sleeve, that is between the tapered head or end and the tapered sleeve or 
collar, for the injection of sealing compound after, before, or during 
deformation, the deformable sleeve advantageously being ported to pass 
such sealing compound to both sides thereof.

In the drawings, a deformable sleeve 10 is shown capable of sliding inside 
a tube 11 to be plugged. The deformable sleeve 10 is shown with external 
ribs 12 close to each of its ends and formed with tapered external 
surfaces 13 converging towards the ends of the sleeve 10. 
Two tapered members 14 and 15 are shown fitting into and engaging at their 
tapers, 16 and 17 respectively, the internal edges 18 at the ends of the 
deformable sleeve 10. The member 14 comprises an enlarged head or end of a 
generally tubular part 20 about which the sleeve-like tapered member 15 
makes a sliding fit. At its other end the tube-like part 20 is threaded at 
21 to take a nut 22 which can bear against the free end 23 of the 
sleeve-like tapered member 15 to coact therewith in forcing or drawing the 
members 14 and 15 together to deform the sleeve 10 as shown in FIG. 2, 
where it can be seen that the tapers 13 on the end ridges 12 
advantageously take a position substantially parallel to the tube walls as 
the sleeve 10 deforms. In this way such tapers 13 help predispose the 
mid-part of the deformable sleeve 10 collapse inwardly rather than buckle 
outwardly due to pivoting action at the inner corners of the ridges. 
The tube-like member 20 has an internal bore 25 that is intersected 
adjacent to the head part 14 by one or more cross-bores 26 so as to 
communicate to the exterior of the member 20 at a position or positions 
within the extent of the deformable sleeve 10. Apertures 27 at about the 
mid-point of the sleeve 10 allow sealing compound 28 to be driven under 
pressure through the bores 25, 26 and apertures or ports 27 during or 
after, or even before, the nut is tightened to make a seal. It can be seen 
that the unthreaded tubular part 20 will support the tapered part of the 
sleeve 15, and the combined action and the position of the cross bore or 
bores 26 is such that the latter, after deformation of the sleeve 10, will 
still communicate with the apertures or ports 27. 
A suitable sealing compound is that marketed by ourselves under the name 
FURMANITE COMPOUND. 
It should be understood that although the invention and its embodiments 
have been referred to specifically for the purposes of tube plugging to 
prevent access via the tube end, it is equally applicable to sealing an 
access pipe or channel-way into a tube end or a bore. All that is 
necessary is for the head part 14 itself to have a bore which, if it 
communicates with the bore 25, will require separate cross bores 26 and 
communicating sealant feed bores if a sealant compound is to be introduced 
into the area of the deformed sleeve 10 independently of the bore 25.