Hydrocarbon Processing - November 2022 - 50

Maintenance and Reliability
cured, both in accordance with the manufacturer's
best practices. The epoxy foam
applied on each panel was further pulled
off and the results compared.
Testing results and discussion.
The range for the epoxy foam was measured
to be within 0.03 Btu/ft. h. °F-
0.05 Btu/ft. h. °F. Such range of thermal
conductivity is comparable to that of vermiculite
and silicon dioxide foams, materials
used for refractory and insulation
purposes in several industries and fireproofing
of structural steel and cementitious
products. TABLE 5 shows the results
at various mean temperatures.
After 1,000 hr of simulated CUI-1 regime
testing, coated multi-layer sections
on grit-blasted and power tool-cleaned
substrates exhibited no failure, as shown
in FIG. 13. Neither cracking nor delamination
of the epoxy foam were detected.
When the insulation was removed by mechanical
means, no corrosion was found
in the bondline between the substrate
and the epoxy foam. After 1,000 hr of
simulated CUI-2 regime testing, coated
multi-layer sections on grit-blasted and
power tool-cleaned substrates exhibited
neither cracking nor delamination of the
epoxy foam (FIG. 14). The insulation was
mechanically removed. No corrosion was
found on the substrate protected with a
2- or 3-layer epoxy foam (FIG. 15). Rust
was spotted on the substrate onto which
the epoxy foam was applied in 1 layer.
This result indicates that the epoxy foam
as a 1-layer system should not be recommended
for wet service at 248°F.
After subjecting both samples (ambient-cured
and post-cured) to 4,500 hr of
spray testing, no delamination or cracking
were observed (FIG. 16). Rust developed in
the vicinity of the scribed lines, as it can be
seen once the foam was removed (FIG. 17).
The thickness of a 3-coat system of the
proprietary epoxy foama
was enough to
reduce the surface temperature of 302°F
to <140°F. Due to the reduction in surface
temperature, hand contact can be maintained
for longer than 5 sec without burn
injuries. Neither cracking nor delamination
were observed in any of the panels, as
shown in FIG. 18.
The results can be seen in TABLE 6.
In all cases, the epoxy foam resulted in
cohesive failure, which implies that the
foam was still tightly adhered to the profile
when pulled. The surface cleanliness
method did not affect the results in any
way, which confirms that the epoxy foam
is tolerant to minimal surface preparation.
Takeaways. Several conclusions can be
drawn from the development of the epoxy
foam. First, the foam uses a solvent-free
phenol formaldehyde Novolac epoxy as a
base and a polyamine as a solidifier-they
react following a typical mechanism of
nucleophilic addition to yield a thermosetting
polymer. The functionality and
chain length of the epoxy resin, solidifier
and modified polysiloxane blowing agent
are proprietary, but they are used to determine
the crosslink density of the foam,
and therefore influence its nature, rigidity,
closed-cell structure, strength and thermal
insulation properties.
Next, the epoxy offers both excellent
FIG. 16. Salt spray after 4,500 hr of testing:
the ambient-cured sample after testing (A),
and the post-cured sample after testing (B).
TABLE 5. Thermal conductivity of the
epoxy foama
Sample mean
temperature, °F
-40
-4
32
68
140
248
302
TABLE 6. Pull-off adhesion
Pull-off adhesion, psi
SSPC SP 10
Ambient-cured
Post-cured
650
530
50 NOVEMBER 2022 | HydrocarbonProcessing.com
SSPC SP 11
Ambient-cured
Post-cured
620
680
2
Thermal conductivity λ
(Btu/ft. h. °F)
0.0373
0.039
0.0403
0.0418
0.0445
0.0488
0.0505
FIG. 17. The ambient-cured sample after testing
and foam removal (A), and the post-cured
sample after testing and foam removal (B).
proven corrosion protection in CUI and
water immersion scenarios and thermal
insulation, which renders it as an ideal solution
for equipment operating at elevated
temperatures. It offers safe touch for
operators working in hot environments
by reducing the surface temperature of
industrial assets below 140°F for longer
than 5 sec of direct hand contact.
Finally, the epoxy foam offers an array
of additional practical features, including
ease of application, short-over coat times,
durability, tolerance to minimal surface
preparation, and quick return to service,
among others.
ACKNOWLEDGEMENT
This paper was presented by the author or assigned
speakers at the Coatings+ 2021 conference.
NOTE
a
FIGS. 18. Panels after exposure to thermal
cycling.
1
BZ5871-EF epoxy foam
LITERATURE CITED
NACE SP0198, " Control of corrosion under thermal
insulation and fireproofing materials-A system's
approach, " NACE International, Houston,
Texas, July 2017.
Lee, S.-T. and N. S. Ramesh, Polymeric foams:
Mechanisms and materials, CRC Press LLC, Boca
Raton, Florida, May 2004.
Complete literature cited available online at
www.HydrocarbonProcessing.com.
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