| Chlor-Alkali
Chlorine is a critical chemical building block, the single material
on which production of other chemicals most depends. Chlorine is
also widely used in drinking water purification and waste-
water disinfection. In the U.S.A alone, 98% of the drinking water
systems rely on chlorine for disinfection. Its use has virtually
eliminated the incidence of waterborne disease, such as cholera,
dysentery and typhoid.
The manufacturing of chlorine requires some of the world's most
corrosion-resistant materials found today. Often, the materials
of production are the vital components for cost-effectiveness
and environmental compliance.
Textiles Coated International (TCI) has engineered an array of
products for chlorine producers based on their novel all-PTFE
material called LFP
Industrial Product. LFP is a flexible but tough PTFE material,
which eliminates concern for chemical attack or the use for a
limiting reinforcement. LFP-based products are long-term solutions
as replacements for rubber products and other materials susceptible
to chemical attack and failure.
Case Study
 Why
LFP Cell Covers are helping solve chlorine production problems?
Over the last twenty years, chlorine cell cover problems have
posed a very serious challenge to the chemical industry in the
United States and abroad. Material shortcomings and environmental
restrictions have been the main issues in solving the cell cover
problems. For instance, the DeNora mercury cell process produces
chlorine gas in rectangular tanks that are called cells. Each
cell requires a flexible cover that confines the chlorine gas
within the cell. Installation of a cover is very difficult because
the cover must be secured to the rectangular frame and the numerous
rod riser assemblies that extend from the bottom to the top of
the cell.
The predominant materials chosen in the past for this application
include rubber and FEP. Rubber would not last long because of
chemical attack by the chlorine gas. The mercury-laden rubber
covers were also a serious and costly disposal problem for companies.
FEP covers solved the problem of chemical attack since FEP is
a perfluoroplastic. However, FEP, like most perfluoroplastics
materials, is a mechanical failure in this application because
of meager tear resistance, stress-crack resistance, and flexing
traits.
LFP Industrial Product is a natural fit as a chlorine cell cover
because it is the only perfluoroplastic with unique mechanical
attributes. The technology that circumvents inherent shortcomings
in conventional perfluoroplastic materials utilizes a cross-pattern
lamination process containing oriented PTFE film. The cross-pattern
will typically incorporate 3 mil or 4 mil film plies. On occasion,
thinner plies will be stacked to create thicker plies, such as
9 mil or 10 mil plies, for the laminate design.
Multidirectional strength and tear resistance enable LFP to survive
installation and movements in the application at thicknesses as
low as 0.012" (0.3 mm). The durability of LFP materials has
been further confirmed in flexing tests, where 0.060" (1.5
mm) LFP product has performed 1,275 times better than the same
thickness in FEP (4,500,500 cycles versus 3,500 cycles).
Today LFP material is successfully covering chlorine cells in
numerous chemical plants throughout the U.S., Mexico, South America,
Europe and the Middle East. TCI recently had the opportunity to
test the physical properties of an LFP cell cover that has been
in service for approximately five years. The strength properties
were exactly the same as the original properties when the cover
was put into service five years ago!
Products
TCI is constantly developing new products for the chlor-alkali
industry based on this technology. A listing of some of these
products can be found below. Please feel free to contact TCI to
discuss how their new PTFE technology can solve your corrosion
concerns.
LFP CC18 is a 100% PTFE laminate engineered specifically for
mercury cell cover service. Unique multidirectional strength
and stress crack resistance allow this flexible, 0.018"
(0.46 mm) PTFE product to be a self-supporting material. No
reinforcements which are susceptible to chemical attack, like
fiberglass, are needed. LFP CC18 has tremendous flexing capability,
easily outlasting fiberglass reinforced materials and other
perfluoroplastic products in demanding industrial applications.
LFP CC18 can be fabricated or molded into all shapes and sizes.
LFP CC18 Properties
- Upper Use Temperature: 500°F (260°C) Continuous Service
- Weight: 27.5 oz/yd (935 g/m)
- Thickness: 0.018" (0.46 mm)
- Tensile Strength: 79 lbs/in (703 N/50 mm)
- Tear Strength: 62 lbs (281 N)
- Standard Colors: Black, Natural and Blue
Download the LFP CC18 Brochure.
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LFP CC20 is a 100% PTFE laminate engineered specifically for
mercury cell cover service. Unique multidirectional strength
and stress crack resistance allow this flexible, 0.020"
(0.51 mm) PTFE product to be a self supporting material. No
reinforcements which are susceptible to chemical attack, like
fiberglass, are needed. LFP CC20 has tremendous flexing capability,
easily outlasting fiberglass reinforced materials and other
perfluoroplastic products in demanding industrial applications.
LFP CC20 can be fabricated or molded into all shapes and sizes.
LFP CC20 Properties
- Upper Use Temperature: 500°F (260°C) Continuous Service
- Weight: 30.3 oz/yd (1020 g/m)
- Thickness: 0.020" (0.51 mm)
- Tensile Strength: 86 lbs/in (765 N/50 mm)
- Tear Strength: 68 lbs (308 N)
- Standard Colors: Black, Natural and Blue
Download the LFP CC20 Brochure.
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| Other Chlor-Alkali
Products |
LFP Tank Liners
LFP Tank Liners have allowed many companies to eliminate corrosion
concerns of their existing tanks. LFP™ Industrial Product
is a flexible, 100% PTFE material that can be fabricated into
many shapes and sizes. The unique, multidirectional strength
of this material allows it to resist tearing and stress-cracking
while maintaining complete corrosion protection of the rigid
wall of the tank.
Many companies have avoided the cost of replacing old tanks
with new ones by using liners made of LFP in thicknesses ranging
from 0.020" to 0.060".
A drop-in tank liner made of LFP can be bolted at flange and
nozzle attachements. It can also be customized in terms of thickness,
color, and conductivity.
Download the LFP
Tank Liners brochure.
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LFP Cell Covers
The rubber cover on a mercury cell is chemically attacked by
chlorine gas produced in the cell. The chemical attack shortens
the cover life, contributes to product contamination, and creates
a serious disposal problem for the chlorine plant.
An LFP CC20 cell cover is installed on the amalgam cell. Because
LFP is inert, the chlorine gas cannot attack it. LFP cell covers
have been in service for more than 6 years, assisting chlor-alkali
producers in improving production and meeting environmental
standards.
LFP Industrial Product is the only perfluoroplastic cell cover
material capable of complex fabrications. The conventional perfluoroplastics
- FEP, PFA, PTFE - possess limited mechanical properties, typically
cracking when severely stressed.
LFP retains exceptional strength properties through the most
severe thermal, chemical, and mechanical conditions. As a result,
LFP covers can be found in use today around the world, setting
record performances in mercury cell production.
Download the LFP
Cell Covers brochure.
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LFP Anode Seals
During the 1960's, mercury cell plants were built around the
world for the purpose of producing chlorine, sodium hydroxide,
and potassium hydroxide. During the operation of the amalgam
process, the anodes in the cell are raised and lowered at various
times. To address this movement, it was necessary to use flexible
materials in the covers on the mercury cells. Some cell producers
developed special seals that extended from the anodes to the
metal covers on the cell. With the flexible seal in place, it
became possible to raise and lower an individual anode without
moving the metal covers on the cell.
For years, the industry used anode seals produced from rubber
materials, such as EPDM. While the rubber products offered the
required flexibility, their resistance to chemical attack by
chlorine was limited. For example, EPDM seals will typically
provide no more than 1 to 2 years in service on a mercury cell.
The limited life of the rubber products has become a serious
problem for mercury cell operators due to the increase in tougher
environmental standards relating to mercury emmisions.
Perfluoroplastics, such as PTFE, offer excellent resistance
to chemical attack by chlorine and most other chemicals found
in industry. However, conventional perfluoroplastics tend to
stress-crack over time in dynamic services, such as the application
involving the movement of the anodes in a mercury cell. For
this reason, LFP Industrial Product was selected as a candidate
for anode seals in a product development program started at
TCI. (In house tests at TCI have always shown that LFP materials
exhibit excellent resistance to stress cracking in even the
most severe fatiguing tests.) Various programs and extensive
product testing culminated in the development of a line of anode
post seals produced from a number of LFP materials. The seals
are very capably serving today's numerous mercury cell operations.
Download the LFP
Anode Seals brochure.
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Uhde Cell Covers
LFP Cell Covers for Uhde cells (pictured bottom
left)
Flexible materials are often required as perimeter seals between
metal covers and frames of Uhde cells. Rubber materials, such
as EPDM, have been replaced by the chemically-inert and tear-resistant
LFP Industrial Product.
Companies will typically still use EPDM as a gasket between
the LFP and the steel frame since corrosion is limited to the
edge of the rubber material.
LFP Cell Covers with tubes (pictured bottom
right)
Rubber-lined metal is commonly found in chlor-alkali production
equipment. Over time, the rubber is chemically attacked, and
often requiring significant expenditures in labor and materials
for maintenance. In mercury cell applications, maintaining rubber-lined
equipment becomes particularly serious due to environmental
and health factors. Today, LFP Industrial Product is improving
the productivity in the chlor-alkali industry by replacing many
of the rubber-lined components that have been traditionally
used for chlor-alkali production.
The photo shows an LFP cell cover with tubes, which has been
engineered to replace a rubber-lined steel cover in a mercury
cell system. The flexible tubes, also made with the LFP material,
are clamped to the anode risers, eliminating the need for separate
anode seals.
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Chemduit-P
Chemduit-P is a durable, high temperature, flexible duct consisting
of an LFP tube with LFP support rings for maximum chemical resistance.
This 100% PTFE flexible ducting has been engineered for low
pressure service for the evacuation or transfer of gases/vapors.
CHEMDUIT-P can handle a wide temperature range -100°F to
500°F (-73°C to 260°C). This duct is available in
a wide range of diameters and lengths.CHEMDUIT-P has positive
and negative pressure capability.
Many special features available: Flanges, cuffs, protective
cuff tails, internal diversion sleeve, colors, conductivity,
etc.
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TCI
Industries and Products