TPi January 2016

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January 2016 Tube Products International 55
Pipe rehabi l i tat ion & repai r
Freeze sealing for pipe repairs
Contractors and maintenance personnel
involved in repairing pipework in
buildings and other constructions have
long faced the problem of making repairs
on tubes and pipes when they are full
of fluid and may not be economically
viable to drain.
The Accu-Freeze® pipe freezing system
is able to freeze a plug in fluid either side
of a repair zone, isolating it, to allow
work to be carried out without draining
the whole system.
Luke Keane, technical support at
Huntingdon Fusion Techniques (HFT),
said, “Accu-Freeze utilises liquid
nitrogen (LN2) in a controlled way to
freeze stationary liquids in a selected
section of pipe or tube.
“By controlling the surface temperature
of the pipe or tube, Accu-Freeze can
accurately and safely form an in-line ice
plug, capable of withstanding 136 bar in
diameters up to 12" (300mm).”
To form an ice plug, the water or liquid
inside the pipe or tube is brought to a
static condition and a specially designed
insulated jacket is placed around the
section to be frozen, upstream from the
repair zone. Once the plug is formed,
maintenance and repair can take place
without draining or shutting off the entire
system.
The controlled ice plug only forms
beneath the Accu-Freeze jacket. It does
not expand outside of this area and
does not create enough pressure to
affect the integrity of the pipe.
The primary advan-
tages of the patented
Accu-Freeze system
include the increased
freezing capability of
LN2 and the ability
to control the pipe
wall temperature
throughout the freeze
process.
The LN2 injections
are automated, which
reduces the operator’s
workload and reduces
the amount of LN2 that
is consumed.
Accu-Freeze can
also be operated
remotely, which makes
it suitable for use
inside ‘hot’ nuclear
areas where personal
exposure must be
kept below certain limits. The Accu-
Freeze technique is able to freeze large
diameters and control the entire freeze
process.
Huntingdon Fusion Techniques – UK
Accu-Freeze uses liquid nitrogen to freeze stationary liquids,
to form an ice plug inside the tube
Clamps vs composites
Composite repair specialist IMG
Composites has published a new white
paper on the subject of composite pipe
repairs versus the more traditional repair
technique of utilising clamps.
The paper, which was published on a
free-to-view online platform accessed
via the IMG Composites website,
provides detail on the benefits and
disadvantages of using each method.
The technical department at IMG
Composites works on studies of
many aspects of the composite repair
business, often writing technical service
reports for the information of clients
and internal development. The paper
is primarily the work of technical
support engineer Stuart McKay,
whose background is in mechanical
engineering, and who previously worked
on designs for steel fabrication before
joining the technical team behind the
award-winning CompoSol® repair
technology in 2013.
The white paper looks at the definition
of the two different repair types before
exploring the selection process,
operation aspects, technical aspects
and commercial aspects, and then
drawing conclusions. This is followed
by an examination of case studies for
both the traditional and new techniques.
MG Composites commercial manager
Ian Taylor stated, “The article is an
excellent addition to our technical
database, which serves as an invaluable
information resource for our personnel.
We chose to publish this in order for our
clients and partners to better understand
the issue.
“It is not a matter of pretending com-
posite pipe repairs are a panacea for all
problems; instead the article is designed
to help clarify areas where composite
pipe repairs are more advantageous
than clamps and vice versa.”
The subject of clamps vs composites
is also briefly explored at www.
, an IMG
Composites website dedicated to
composite pipe repairs.
IMG Composites Ltd – UK