Hydrocarbon Processing - October 2022 - 58

Maintenance and Reliability
stantly looking for ways to reduce labor
or implementation costs by using other
non-conventional, cost-efficient alternatives.
One of these alternatives, which
seems to be of growing interest, is the use
of thermal insulating coating systems that
can also provide corrosion resistance.
This article details the development
of a novel epoxy closed-cell foam insulating
and corrosion protection barrier
by a coating manufacturer. Design considerations
of such a material, fitnessfor-service
testing and results will be
presented, as well. Potential application
areas and benefits, including worksite
personnel and CUI protection, will also
be discussed.
Background. Polymer foaming, simply
defined, is the technology that allows the
generation and stabilization of bubbles
TABLE 2. Proprietary epoxy foama
Excellent corrosion
protection
Cool-to-touch properties
Excellent thermal
insulation
No primer or topcoat
required
Solvent-free
Durability/aging
Tolerance to minimal
surface preparation
Ease of application
Short overcoat times
Fewer layers (coats)
required
Quick return to service
within a polymeric matrix.2
When a system
is excited into an unstable foaming
state, a stabilization mechanism must be
established in time to transform the foaming
into a stable foamed product. In theory,
it sounds very simple to accomplish;
in reality, it is not. Produced foams can be
categorized in accordance with different
perspectives,2
as detailed in TABLE 1.
Epoxy foams are becoming a more attractive
alternative to the more prevalent
urethane foams used as thermal insulators.
Reasons for this include the mechanical
strength of epoxy matrices and
the elimination of toxic or sensitizing
isocyanates, typically used in the polyurethane
formulations.3
Additionally,
some literature has cited the rigidity and
dielectric properties (volume resistivity,
dielectric constant and dissipation
factor) of epoxies over polyurethanes.
design considerations
A system that would show no signs of failure or damage after exposure to simulated corrosion under insulation
scenarios, salt spray and water immersion.
A system that could off er safe touch by reducing the surface temperature of the industrial equipment
to less than 140°F, allowing direct hand contact.
A system with reduced heat transfer across its volume.
A system with adequate adhesion to mechanically prepared and clean substrates without any conditioning,
and robust enough to provide corrosion protection by itself.
Solvent-free epoxy systems show greater mechanical properties when compared to solvented formulations.
Experimental work has shown that solvent remaining within the epoxy can hinder the cross-linking process,
resulting in lower exotherm, initial curing rate, reaction order and glass transition temperatures.6
A foaming system that would show no cracking or sign of deterioration when subjected to thermal cycling.
A foam that could be applied onto substrates cleaned to the requirements of both SSPC-SP 107 and SSPC-SP 118
and profi led to at least 1 mil and successfully off ers corrosion protection.
A system that could be conveniently applied by brush, cartridge spray or heated plural component airless spray.
A system that could be overcoated with additional coats, if needed, as soon as possible.
A foaming system that would need fewer layers (coats) than most typical coating systems to achieve insulative
properties through a controlled catalytic process.
A foaming system with shorter drying times to provide a defi nite appeal for asset owners.
Whether epoxies or polyurethanes, polymeric
foaming requires the presence of a
blowing agent, herein defined as a substance
that produces a cellular structure
in a polymer mass by releasing a gaseous
phase due to thermal decomposition or a
chemical reaction.4
The blowing agent plays a significant
role in both the manufacture and
performance of the polymeric foam. In
the case of foaming of high molecular
weight polymers [e.g., polystyrene (PS),
polyolefins, polyamides, polyester], the
blowing agent modifies the rheology of
the polymer during foam formation and
shaping. In cases where polymerization,
foaming and shaping all happen in one
step, [e.g., during the formation of typical
polyurethane (PU), epoxy or phenolic
foams], the blowing agent not only affects
the liquid viscosity and thermal hisFIG.
1. The proprietary epoxy foama
as applied inside a beaker and allowed to cure until achieving growth of up to three times its original thickness.
58 OCTOBER 2022 | HydrocarbonProcessing.com
Practical
Technical

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Hydrocarbon Processing - October 2022

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