Case Studies

Case Number 1: Chemical Water Treatment Tank Exchange

Problem: Chemical Water Treatment Tank Exchange

A leading nuclear facility needed to replace their older chemical water treatment tanks, have new ones installed and utilize a PA DEP certified provider to validate the installation.  They also needed a proven general contractor to manage the process due to the importance and sensitivity of the project. These chemical water treatment tanks are vital components of a process that controls water chemistry and biological pathogens for the facility’s cooling water system.

Solution: Exchanging, Installing and Certifying New Chemical Water Treatment Tanks  

The nuclear facility selected Electro Chemical Engineering and Manufacturing Company as the general contractor and installation certification resource due to their experience and high quality reputation for managing critical condition projects.Chemical Water Treatment Tank Exchange

Electro Chemical has overseen the following parts of the process:

The removal of three existing polyethylene tanks. These tanks were cut up inside the treatment room and placed into dumpsters.

The removal of one steel tank and associated injection skid.

The installation of three new polyethylene tanks

The replacement of four Pulsafeeder chemical injection pumps.

Refurbished pump bases were taken off-site for rework and pump installation

The removal and reinstallation of existing mechanical utilities to facilitate tank rigging

The replacement of all CPVC piping from the new tanks to the new injection pumps.

The removal of one containment wall.

The removal of existing coatings on the containment floor and walls.

The application of HD257 primer and HD253 epoxy top coat system for the floor and inside walls of the containment area.

Inspection and PA DEP certification records for all installed components and pump motors were completed and submitted to PA DEP.

Benefits: Long Term and Effective Solution Completed On Time and Within Budget

Electro Chemical took on a very challenging project within a sensitive environment as the general contractor leading a team of providers to remove the old chemical water treatment tanks, install new ones and PA DEP certify those installations along with coating the containment walls and floor to ensure sealing.

By selecting Electro Chemical as the general contractor for these critical PA DEP regulated activities, the customer was assured the project was completed correctly, on time and within budget.  The nuclear facility now has a long term and effective solution.

Case Number 2: ECTFE (Halar) Lined Tank Trailer Container

Problem: Small Container Loading

A prominent company’s agricultural chemical division had struggled, for years, with the difficult handling process utilized for loading and unloading a highly corrosive material into small containers. Their process required filling 100 plastic drums with this acidic material which normally took 8-10 hours of time to complete and tied up more resources than desired.  The issues with this process of small container loading caused the project engineers to re-evaluate the situation and consider alternative solutions.Lined Tank Trailer Container

Solution: ECTFE (Halar) Lined Tank Trailer Container

Their search led to the fluoropolymer lining of a larger container. The container finally selected was a 4000 gallon tank trailer lined with Ethylene Chlorotrifluoroethylene (ECTFE), otherwise known as Halar, sheet material that resists corrosion from a wide range of strong acids, alkalies, metal etchants, liquid oxygen and organic solvents.

ECTFE (Halar) was selected for this application not only for the excellent permeation resistance and durability, but also for the significant cost and time savings provided in comparison to the small container process. The tank trailer, 48’ long and 4’ in diameter and designed for operation at 50 psig and 220°F, was sent to Electro Chemical for installation of the ECTFE lining.

The ¼” thick carbon steel surface was sandblasted to facilitate a strong bonding base, primed, and multiple coats of a specially formulated elastomeric adhesive was applied to both the tank trailer surface and the knit glass backing of the 90 mil thick ECTFE tank lining.

The ECTFE sheets were supplied in 48” wide by 50’ long rolls and custom shapes were cut to minimize the number of joints.  Instead of abutting or overlapping the sheets, a 1/16” to 1/8” segment was left between the adjacent edges which allowed the sheets to be heated and rolled against the tank trailer wall and the adhesive to set to maximize bonding and eliminate any trapped air. Electro Chemical also ensured a pin-hole free lining by using a gas welding process including 1/8” diameter ECTFE weld rods. Once this was completed, all excess ECTFE was ground away leaving a flush and smooth surface.

In addition, joints were never made at corners to mitigate excessive stress in the welds. The ECTFE sheet was rolled over all corners and joints were developed several inches away on the flat surfaces. Then the entire application was inspected visually for surface defects, the dimensions and tolerances inspected and all lined areas tested with a dielectric spark tester adjusted to 10,000 volts AC.

Benefits: Lower Cost, Less Time and Long Service Life

The client gained great benefits from this ECTFE lined tank trailer solution. After a process that required 8-10 hours of time, filling the ECTFE lined tank trailer was complete within 30 minutes. This provided significant cost savings and the project engineers involved have reported no issues after more than 18 months of usage.

Due to the precise and reinforcing measures taken in installing the strong corrosion protection lining, the service life should extend for years to come. If repairs are ever needed from damage done during service, all that is required is to cut out the damaged area, apply another ECTFE sheet of the same dimensions and repeat the welding process described above. The ECTFE lining meets all the requirements of the ICC and Department of Transportation.

Case Number 3: Hydrofluoric Acid

Problem: Chemical attack of HF

A large specialty chemical company had experienced multiple equipment failures over a period of several years in a reaction process involving an aqueous hydrogen fluoride (HF) solution. The reactor vessel and internal components were constructed of nonferrous high-nickel alloy. The alloy welds were being chemically attacked, and certain components, such as the agitator experienced life cycles as short as 3 weeks. The extremely high cost of downtime and maintenance over a sustained period drove the process engineers to seek alternative solutions.

Solution: E-CTFE lining system

The search led to fluoropolymer coating and lining systems. The application required a system that could withstand temperatures to 230°F (110°C) operate in a moderately abrasive aqueous HF slurry, and be chemically resistant to the non-HF components of the solution. Initial immersion tests in the chemical solution demonstrated that ethylene chlorotrifluoroethylene (ECTFE), a partially fluorinated fluoropolymer was resistant to the chemical attack. ASTM C 868 laboratory cell tests further confirmed that ECTFE in a bonded sheet lining system was resistant to both chemical attack and permeation in this environment.

As a result of these tests, the customer ordered a new reactor system consisting of ¼ in. (6-mm) carbon steel shell with a 90-mil (2-mm) ECTFE fabric-backed sheet lining. The lining was bonded to the shell with an elastomeric adhesive. The agitator shaft and blades were made of type 316 stainless steel, with a 40-mil ECTFE coating applied using a special primer and electrostatic powder spray process. The reactor system was purchased at a fraction of the cost paid for the corrosion-resistant alloy system that it replaced.

Benefit: Lower cost and longer life cycle

The new fluoropolymer-lined reactor ran continuously for 6 months before being shut down for normal preventive maintenance. Inspection of the reactor interior revealed no perceptible degree of chemical attack, blistering, discoloration, cracking, or abrasion damage. The agitator was removed and thoroughly inspected. The results showed it likewise was in a “like new” condition, with no chemical attack, delamination, discoloration, or abrasion damage. The system was put back into service and has continued to operate without failure. The customer subsequently purchased an identical fluoropolymer-lined reactor system for another plant.

Case Number 4: Hydrochloric Acid

Problem: HCL chemical attack of glass lined reactor and high maintenance costs

A  chemical manufacturer had (6) 300-gal glass lined reactors containing mixtures of hydrochloric acid (HCl), acetic acid (CH³COOH), and various other reactants.  Operating temperatures were in the 200 to 275°F (93 to 135°C) range, and the system periodically was subjected to full vacuum conditions.  Physical shocks frequently caused minor damage in the form of small chips in the glass lining.  These chips routinely were repaired with tantalum alloy plugs.  Concurrent with the repairs, production engineers often experienced unacceptable variations in the purity of the finished product.  The tantalum alloy plugs were ultimately determined to be the contamination source.

A decision was made by the production management to keep spare glass-lined vessels on site and to completely replace damaged vessels, rather than repair them with tantalum plugs.  The heavy expense of changing out and relining the reactors each time the glass chipped eventually made this option unacceptable to management.

Solution: PVDF high performance coating

In search for a cost-effective alternative, fluoropolymer coating and linings were evaluated.  The combination of aggressive chemicals, full vacuum conditions, temperatures >200°F and heavy physical stresses made this particularly challenging problem.

One option with a history of success in similar environments was a high-build polyvinylidene fluoride (PVDF) dispersion laminate system.  Rather than run an ASTM C868 cell test in the laboratory to test for chemical attack and permeation, the customer decided to test a system in actual operations.  The glass lining was stripped from a reactor and agitator, and they were coated with a 40-mil PVDF dispersion laminate reinforced with carbon fiber cloth.

Benefit: Lower overall costs, less downtime for repairs and increased production

The PVDF laminate system was placed in service and ran for 4 months without chemical attack, permeation, or failure caused by mechanical damage of the lining.  Based upon these results, the customer converted the remaining five glass-lined reactors and agitators to the carbon cloth-reinforced PVDF dispersion laminate.  The cost of the PVDF coating system was significantly less than that of the equivalent glass-lined system, but the real payback has been from increased production and elimination of unscheduled downtime to change out reactors.

Case Number 5: High Purity Sulfuric Acid

Problem: Impurities caused by permeation of metallic ions

A manufacturer of high-purity sulfuric acid used as a cleaning solution by several large producers of semiconductor devices required a lined tank container for international shipments and long haul shipments within the U.S.  The lining material would have to be resistant to 98% sulfuric acid and most importantly maintain the stringent purity requirements needed by the semiconductor industry.

A  68” I.D. x 198” straight side “tank container” had been previously coated internally with another manufacturers spray applied system which had failed to prevent metallic ion contamination of the load. The chosen lining system would not only have to acid resistant but also not impose capacity restrictions because of it’s weight, and be extremely resistant to both the thermal and mechanical shock associated with the container transportation.

Solution: PFA bonded sheet lining system

Electro Chemical forces stripped the internal areas of the container, neutralized the carbon steel substrate and grit blasted the surface to white metal.  All internal areas of the container were then lined with a 90 mil thick PFA knit glass backed sheet lining.  The lining was carried through all nozzles and out over all flange faces.  All seams were welded using a hot gas process which incorporates a 1/8” diameter PFA weld rod and PFA cap strip.  All internal areas were inspected and tested using a dielectric spark tester and helium leak tested to guarantee that the lining was pinhole free.

Benefit: Increased purity by reducing permeation of metallic ions

The PFA lining system has been successfully preserving the purity of the sulfuric acid product- with no fillers or plasticizers to leach out and contaminate the sulfuric acid. PFA has proved to be an excellent choice for handling of high purity corrosive chemicals.

Case Number 6: Field Installation of PVDF Fluoropolymer Sheet Lining

Problem: Damaged liner needed field repair completed in 2 weeks and extend life of liner to minimize downtime in production.

Lining of a spent sulfuric acid storage tank required repairs to be completed on site within 2 weeks to avert a plant shutdown.  The plant engineers were provided with three options 1) install spray-on epoxy liner; 2) remove the tank and have it recoated with a spray-on fluoropolymer or 3) have the failed lining stripped and a new sheet lining installed in the field.

Research indicated an epoxy lining would not withstand the process chemistry.  The time and money required to uninstall and ship the tank to be coated or lined at a contractor’s facility were deemed unacceptable to meet the 2 week schedule.

Solution: Field installed PVDF liner

Field installation of a fluoropolymer PVDF lining was the choice to provide the quickest turn around and longest life cycle.  The client already had two other vessels in the same application performing very well with PVDF sheet linings so they were confident they would get the desired life cycle with the PVDF lining.

Within a few days of the initial phone call Electro Chemical was onsite with eight confined space trained field technicians and the necessary equipment and materials to complete the job within 2 weeks.  The vessel was stripped, repaired and grit-blasted to a white metal finish in preparation for the lining installation.  Our crews then began working around the clock until the PVDF sheet was installed inside the vessel.

Upon completion of the interior blast the tank’s inner surface was primed and coated with an adhesive before installing the polyvinylidene fluoride (PVDF) sheet lining.  The 90 mil- thick fabric backed sheet lining system was bonded in place using Electro Chemical’s proprietary elastomeric adhesive system which provides a flexible, tenacious bond capable of withstanding stresses from the differences in thermal expansion between the fluoropolymer lining and the carbon steel shell.

The lining was applied continuously to all wetted surfaces, including through the nozzles and out over the flange faces to provide a pinhole-free corrosion barrier.  The bond between the PVDF fluoropolymer and the substrate surface was tested in accordance with ASTM D-903.We provided client with documented installation procedures, plastic welders well-trained on American Welding Society (AWS) standards, and plastic welds tested in accordance with ASTM C-1147 to ensure a quality installation. Once the lining was installed, internal areas were visually inspected and tested for pinhole leaks using a dielectric spark test.

Benefit: Reduced overall life cycle costs and field relining completed on time to eliminate down time.

The installation was provided at the customer’s location which eliminated the need to decouple the tank pipe connections, hire a crane to remove the tank and shipping costs for the oversized load. The field installation was completed within 2 weeks working 24/7 which avoided shutting down the plant and the PVDF liner will provide a longer life cycle than traditional epoxy coatings.