Rigid Polyurethane foams are commonly used for the insulation of pipelines where hot or cold liquids are
being carried through, because they minimise the exchange of heat within the pipe and surrounding
environment. The main applications of rigid foam insulated pipes are chemical plant construction, District
Heating and oil and gas pipelines. Various technologies are used to apply foams to the pipes, according to their
sizes and applications. Cannon have developed suitable solutions for all the needs, providing high foam quality
and efficient methods of distribution.
Rigid Polyurethane foams, used for the insulation and protection of pipes for more than 30 years, are now more extensively used
than ever. Thanks to their outstanding performances and ease of application they are progressively replacing other insulating
media. The most popular areas of use are
• District Heating systems
• oil and gas pipelines
• heating services for power stations, chemical plants and refineries
Polyurethane foam's superior insulation properties prevent heat loss or maintain temperatures in cold environments to
prevent freezing. These energy saving performances improve the cost efficiency of customers' fluid distribution lines.
If we add their high mechanical strength, excellent adhesion, flexibility and good flow-ability, required to properly fill the
cavity around the pipe' section, we understand why this reliable, efficient and long lasting material quickly gained the
favour of so many contractors and end users.
Polyurethane foams can be efficient over an extremely wide range of temperatures, from the extreme cold of cryogenic
applications, where temperatures can be as low as -190°C, to an intense heat approaching 150°C.
According to the needs, insulated pipes' dimensions stand in a range from 10 mm in diameter of small plumbing pipes, up
to 2,000 mm diameters of the largest heating pipes. Insulation thickness vary accordingly, up to 200-250 mm for the most
severe working conditions.
Pipe manufacturing techniques In order to assure the most effective insulation to a vast array of pipes, different in diameter, length and type, various
application techniques have been developed and applied, and both discontinuous and continuous manufacturing processes
In continuous production methods – adapt to large pipes produced in huge quantities – foam is applied to the inner
pipe either by a moulding or a spray operation. Then an external protecting pipe is extruded or wound around a quasistable
foam. Cannon supplied recently complete plants for both pouring and spray techniques.
A major Austrian manufacturer of small pipes (the inner tubes having a diameter of 10 to 12 cm) installed a
continuous pouring system based on one high-pressure multicomponent dosing unit able to produce in rapid sequence
pipes insulated with foams of different densities and characterised by different reaction and rise profiles. Foam is
applied on the moving pipes, over a flexible protecting film which is unrolled under the steel tube and is immediately
“wrapped” around it when the foam starts rising.
The pressure exerted by the rising foam is contained using a lateral caterpillar system, which clamps from both sides the
running manufact (pipe, foam and protective film) accompanying it for a period of time sufficient to guarantee
the mechanical stabilisation of the foam and its even distribution in a precise annular circle between the inner pipe
and the outer lining film.
Closed-loop control of components output and ratio guarantee to this client a constant foam quality, even in
presence of a very wide range of ambient temperatures in their working place. The availability of multi-component
dosing permits a quick adjustment of the catalysis pack when required by the changing process parameters, and a very
intuitive MMI (Man Machine Interface) helps the operators in programming the various lots of pipes and in the following
statistical control of production.
For the manufacture of large pipes Cannon have supplied in the past year several large spray machines for the continuous
foaming plants of the leading manufacturers of oil and gas piping systems based in the Arab Emirates, India and Austria.
All these supplies are characterised by high-pressure metering machines, able to supply up to 40 kg per minute of rigid
foam, dedicated – and recently developed – L-shaped spray heads, their supports and all the ancillary equipment required
by an automatic foaming process. This includes the ReCo Air system, a pneumatic closed-loop controlled device acting in
real time on the head's nozzles position. The computerised flow control monitors the performance of the pumps every
few milliseconds, and immediately reacts to any deviation from the set values commanding a readjustment of the
relevant nozzle on the mixing chamber. This guarantees that the mixing operation, occurring just before the spray nozzle, is
performed at constant values of pressure, for a repeating and precise application of the foam.
In all cases, the winning factor to get the contracts was the availability of a spray head able to minimise the overspray
rate: this term refers to the amount of foam which gets lost around the pipe during the application of the spray patters.
The absence of air while forming the spray pattern helps in optimising the projection over the target and in obtaining a
very regular thickness of foam across the whole sprayed surface. Superior foam quality and reduced overspray –
compared with their existing foaming equipment – were immediately noticed by all the clients, when foaming trials
were executed in Cannon Afros R&D labs in Italy.
Thanks to the application methods, the continuous foaming technologies allow for consistent production and a relative
saving in materials: filling densities can be optimised, and foam overpacking is not necessary. Applying an external
casing over a stabilised foam also considerably reduces the thickness of the outer plastic layer, thus providing a further
On the other hand, the continuous system is more suitable for long runs of production of the same diameter, it involves a
certain loss of efficiency when setting up the size of the new pipe to be insulated, and requires a capital investment in
equipment superior to that needed for a discontinuous foaming plant.
Discontinuous production usually involves the injection of foam in the cavity between the steel inner pipe and the outer
high density polyethylene casing pipe. Standard steel pipe lengths for this process are 6, 12 and 16 m. Depending upon
the size of the pipes, the injection technique involves the manual or mechanically assisted insertion of the inner steel
pipe in an outer plastic casing, normally keeping them at regular distance using hollow plastic spacers with a annular
design. After this preparation, both the ends of the pipe are sealed with caps, the pipes are placed over an inclined support
and the injection of foam is performed inserting the nose of a mixing head in a pouring hole placed in one of the ends.
The foam flows throughout the entire cavity and fills it evenly.
To make sure that no air voids gets trapped in the rising foams, various techniques are employed to help venting the air
out of the cavity. Some foam overpacking is common, especially when the section to be filled is reduced and the
length of the pipes constitutes an obstacle to the flow of the liquid formulation.
Cannon have recently supplied various complete plants, for small and large diameter pipes, in France and Russia.
These orders are the fruit of a combination of factors that Cannon have been able to offer to their customers:
• a superior mixing technology for high quality foams.
• the capacity to handle entire projects, from the large storage tanks for the raw materials till the mixing head, including all
safeties and production planning & control protocols.
• the capacity to speak the customer's “language” technologywise, proposing solutions tailored on their actual needs and
not on “off-the-shelf ” equipment.
• a local presence with direct offices, offering qualified service technicians and stock of spare parts.
• an international experience upon the latest news and developments in several fields of the PUR technology, easily
and quickly transferable from one to another continent.
This allowed Cannon to gain significant contracts – even exceeding one million Euro value each – from customers that
were regularly buying from Cannon's most qualified competitors in the Polyurethane equipment field.
Piping business: small or large, few or many, talk to the local Cannon office. They can offer you some smart ideas!