Note: Descriptions are shown in the official language in which they were submitted.
107~;979
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
having applications in the chemical and power supply
industries. A conventional construction of 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 heat exchanger fluid. These tubes may have to
withstand substantial pressures, say up to 2000 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 a defective tube, but with only
moderate success.
I have worked on solving these problems of providing
satisfactory plugging by way of a 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
engagemeht with the interior of the tube at each end of the
sleeve. Specifically, the sleeve has an external ridge at
or near each of its ends shaped to co-act with the tube or
bore wall on spreading of the sleeve by the tapers and assist
in deforming the sleeve by buckling inwardly a-t i-ts mid-region.
A substantially central carrier member may have bores so
as to allow injection of a flowable sealing compound therethrough
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and through apertures in the sleeve.
'I`he present invention arises from my development of this
plug using corrosion resistant materials, such as stainless
steel, and I have found that, such materials tending to be
relatively hard, tooth-like formations of the sleeve ridges
have themselves bitten into the material of the bore to be
plugged and usually resulted in the achievement of a
satisfactory seal without sealant introduction. Furthermore,
only the sleeve-end furthest into the bore need be so formed
and advantages!larise, by way of resistance to vibration-
loosening, if a flange, which may be integral with the other
end part of the sleeve, is provided to bear against the end
of the bore to be plugged.
One preferred embodiment of this invention therefore
: 15 comprises an inner member carrying or integral with a tapered
: member for entering and spreading a tooth-section ridged end
; part of a surrounding sleeve having, preferably integral
therewith, a flange at a spaced position, typically its other
end. Then, means for acting between the inner member and the
~: 20 flange, such as a nut on a threaded end of the inner member
where it protrudes through the flange on the non-sleeve side
to bear against such flange, serves in drawing the tapered
part into the sleeve. In such a structure, especially
where the flange is integral with the sleeve, further
protection against vibration loosening is provided where
the nut enters a neck-like extension from the
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flange which extension can be struck, say with a hammer,
to deform into locking engagement with flats of the nut.
Such, or analagous provision is, of course, equally,
applicable to other types of tube plug having relatively
movable parts, for example that of our above-mentioned
application.
One embofiment of the invention will now be specifically
described by way of example, with reference to the
accompanying drawings, in which:
Figure 1 is a sectional view of a tube plug;
Figure 2 is another sectional view similar to
Figure 1 but showing the tube plug operated to seal a
` bore; and
Figure 3 is an end view of the plug of Figure 1.
In the drawings, an end-spreadable sleeve 10 is, when
unspread, capable of sliding inside a tube or bore 11 to
be plugged. An inner member or spindle 12 has clearance
13 within the sleeve 10 except for a tapered head or end
, 14 for spreading the sleeve 10 at its end 15 where an
,~ 20 external rib 16 has external surfaces converging towards the
i end 15 from an edge 18. At its other endj the sleeve 10
has an exterior flange 20 beyond a sleeve part 21 exteriorly
thickened, usually to the same initial diameter as that
of the rib, but perhaps to the nominal diameter of the
25 tube or bore to be plugged, if different. The central,
;, thinner wall portion 22 of the sleeve materially assists
inward buckling thereof when the sleeve-end 15 is spread
and its rib-like rim 16 engages the bore 11 to be plugged.
The spindle 12 extends through the flange 20 and is
threaded at 24 to be engaged by a nut 25 which, on seating on
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the flange 20, will serve in drawing the spindle into the
sleeve and thus spreading end 15 thereof. The flange 20
provides ready seating against the end of the bore to be
plugged, typically against a flange of a heat exchanger
housing vessel, and is area of contact therewith ensures
good stability and resistance to vibrations effects.
About the position at which the nut 25 seats on the
flange the latter has a thin-walled neck or collar extension
28 that is deformable, say by hammer blows, to lock the
nut 25 in a tightened position.
In fitting, see Figure 3, the spreading of the sleeve
end 15 caused by tightening of the nut 25 causes, for a
sufficiently hard material of the sleeve, the edged rib or
rim 16 to bite into the interior surface of the material
defining the bore or tube to be plugged. Such action is
normally sufficient to provide a satisfactory seal. Where
this does not occur say due to the interior of the bore
being badly corroded, or the material defining itbeing too
hard, provision may be made for injection of sealing
compound such as one of the "Furmanite" Leak Sealing Compounds
via apertures in the sleeve, either from a blind longitudinal
bore of the inner member or spindle and intersecting
; cross-bores to the sleeve apertures as in our above-mentioned
application, or by injecting through a nipple or other
provision at the flange.
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