Products & Services: Epoxy Cladding for Tubesheets
Examples
of Deteriorated Tubesheets
Examples of tube-to-tubesheet Configurations
The Tubesheet Cladding can be applied
to any tube-to-tubesheet configuration experiencing any level of
deterioration providing structural integrity
is not threatened. The diagrams below show the cross-section
of three examples. Each configuration is shown as it would appear
with a new or slightly corroded tubesheet (upper half) as well
as with a more severely corroded tubesheet (lower half).
Epoxy Cladding for Tubesheets
A leak-tight joint between tube and tubesheet
is critical to the proper operation of steam surface condensers
and other heat exchange equipment.
Loss of tube-to-tubesheet joint integrity can be
generally traced to three root causes: corrosion and/or erosion of
the tubesheet material, improper rolling of the tubes during installation,
and mechanical stresses during operation.
Tubesheet corrosion is generally caused by dissimilarities
with higher alloy, more noble tube material. This situation is becoming
more and more prevalent as stainless steel and titanium tubes are
being retrofitted into older condensers and heat exchangers. Loss
of tubesheet metal due to corrosion leads to the compromise of tube-to-tubesheet
joint integrity.
The alternatives for tubesheet protection are generally
cathodic protection or the use of coatings.
Cathodic protection of tubesheets is difficult
due to variations in water quality, turbulence, and the inability
to space anodes and reference cells effectively. Also, since cathodic
protection systems do not have high visibility, they receive little
attention from operation and maintenance personnel.
Thin film coating systems of 25 to 80 mils have
failed due to improper application, and because a thin film thickness
is insufficient to withstand the long-term abuse of cooling water
systems.
The Plastocor® Process for tubesheets entails
the precise molded application of an ultra durable protective Cladding.
The tubesheet and tubes are completely encapsulated and locked in
by a thick, 100% solids epoxy shield of 200 +/- 40 mils. This polymeric
shield is in addition to the thickness of material required to rebuild
lost tubesheet metal.
This patented process fashions a radially flared,
high gloss, inlet and outlet tube opening, serving to dramatically
reduce flow resistance and fouling. For on-line tube cleaning systems,
a reduction of sponge ball wear is also realized.
The substantial nature of the System adds strength
and integrity to the tube-to-tubesheet joint. Tube push-out strength
enhancement of 2000 lbs has been documented simply due to the application
of the System.
The Plastocor® Cladding withstands physical
abuse, impact, and other physical/chemical stresses associated with
the operation of a cooling water system. The System is designed to
endure these rigors over the very long-term. Case histories date
flawless performance back to 1963.
The Plastocor® System is engineered as the
permanent solution to tubesheet corrosion problems.
