Veolia uses Knovel
Corrosion to pinpointcause of valve failure
In their words

Key insights

About Knovel Corrosion“Knovel Corrosion quickly gave
us rankings for plastics in manydifferent environments ... It also
provided supporting case studies tohelp explain our conclusions. I had
never seen all this within a single
reference source before.”• Polyvinylidene fluoride (PVDF)
should not be used with strong
alkalis, fuming acids, polar solvents,
amines, ketones and esters.

Knovel Corrosion is a solution ofsmart tools, case studies and highquality content that help engineers
mitigate the impact of corrosion.
Its unique coverage spans:

Mel Esmacher, P.E.
Veolia WaterTechnologies& Solutions• A plastic compatibility guide within
Knovel Corrosion confirmed
variance in cracking performance
depending on the manufacturer.

• A case history of stress cracking in
PVDF was traced to high alkalinity
and high temperature.

• Metals• Plastics• Coatings

Customer profile

Case study overview

With operations in 130 countries and over 10,000 employees
worldwide, Veolia Water Technologies & Solutions leverages acomprehensive set of chemical, equipment and digital enabled
services and products to solve the toughest water, wastewaterand process challenges around the globe. It serves customers
across all industries, including food and beverage, metals
and mining, power, pharmaceutical, oil and gas, chemicals,
petrochemicals, pulp and paper, and utilities.

Leaks were detected and brittle cracking was observed in various
parts of a unique type of check valve. As part of the water
treatment process, it had been exposed to a caustic chemical
mixture containing 20% to 40% sodium hydroxide.

To provide these customers with best-in-class solutions anddistinguish itself from its competitors, Veolia invests significantly
in its research, development and customer support capabilities.
Employing over 1,000 researchers and engineers across multiple
lab facilities around the globe, it is at the forefront of water andprocess treatment technologies.

Using Knovel Corrosion, the Veolia team uncovered how muchvariability could be present in PVDF depending on the vendor
and the process environment. They delved into the database forplastic compatibility. This revealed that it was possible, depending
upon the type of PVDF used, for environmental stress cracking
to develop.
Downtime at some plants can cost more than $100,000 a day.
The authoritative information sources found in Knovel Corrosion
enabled the Veolia engineers to provide a clear direction andadvise on better material for applications.

Read the full case study on the following pages. →Figure 1: Knovel Corrosion
provides detailed data onPlastics Design Library (PDL)
values at various temperatures.

ChallengeSolution

Mel Esmacher, P.E., is a senior materials and metallurgicalengineer at Veolia’s R&D and Customer Analytical Services
Laboratory in Tomball, Texas. A big part of the job for Esmacher
and his team is helping customers solve corrosion problems.
Customers send water samples and damaged components
to the lab for analysis and recommendations on alternative
materials or treatment programs.

Esmacher and his team turned to Elsevier’s Knovel Corrosion
solution to investigate the issue. Research using the databaseprovided several insights. One reference that turned up in thesearch indicated that PVDF should not be used with strong
alkalis, fuming acids, polar solvents, amines, ketones and esters.
The document added that when used with strong alkalis, PVDF
can suffer from brittle Environmental Stress Cracking (ESC).

“We look for strategies to mitigate corrosion,” said Esmacher.
“Many times, the wrong type of metal alloy, plastic or othermaterial is being used in an application.”“Knovel Corrosion helped us to discover that the cracking
resistance of PVDF in caustic solutions varies markedly
depending upon the testing protocols used by the manufacturer
and the method used to manufacture the material,” said
Esmacher. “We also discovered that certain manufacturers notedthe appearance of cracking damage when NaOH was present inthe water.” (Figure 1)

A recent case involved the failure of a unique type of check valve.
As part of the water treatment process, it had been exposed
to a caustic chemical mixture containing 20% to 40% sodiumhydroxide (NaOH). Leaks were detected and brittle cracking wasobserved in various parts of the valve, such as the housing anddiaphragm seals, although it had been in operation for only a
few months.
Examination in the lab revealed that the valve used a plastic
known as polyvinylidene fluoride (PVDF), which is a semicrystalline thermoplastic fluoropolymer. PVDF is chemicallyresistant to most acids, bases and organic solvents. It is also
resistant to wet and dry chlorine, bromine and other halogens.
“Initial testing of this type of plastic showed a good rating andperformance for this water treatment product,” said Esmacher,“so it should have been able to withstand these conditions.”
Clearly, a deeper investigation was required.

Once he understood how much variability could be present
in PVDF depending on the vendor as well as the processenvironment, Esmacher delved into the Knovel Corrosion
database for plastic compatibility. This revealed that it
was possible, depending upon the type of PVDF used, forenvironmental stress cracking to develop, as test samples
showed cracking within 35 days in 100% of samples when
exposed to a 10% NaOH solution. Another document thatcame up using a search within Knovel was a case history ofstress cracking in PVDF (Figure 2). It highlighted embrittlement
in a PVDF pipe section after one month in a 20-30% NaOH
concentration at 80oC. Cracking was traced to high alkalinity
and high temperature. The remedy in that case was to reduce thetemperature and alkalinity by improved process control.

Figure 2: Knovel Corrosion case study showing ahistory of stress cracking in PVDF.

Solution, continued
Additional work in the Veolia lab confirmed that the type ofPVDF used in the valve was reinforced with fiberglass. This
increased cracking susceptibility by altering the material’s
chemical resistance.
“The plastic compatibility guide within Knovel Corrosion
confirmed variance in cracking performance depending on thePVDF manufacturer. It also identified specific data confirming
cracking problems in caustic test solutions,” said Esmacher.
“Several different sources within Knovel Corrosion made it
clear that the PVDF used in the valve housing was not crackresistant to the chemical properties of the fluid it contacted.”
As several experts within Veolia had access to Knovel Corrosion,
Esmacher could share findings with his collaborators, answer
questions and agree on the best course of action.

ImpactAt Veolia, about 50% of the lab work is routine, such as typicalwater analysis test grids and corrosion monitoring. But in theother 50% of cases, challenges appear that call for in-depth
study of the manufacturing variance and potential failings ofmaterials in certain environments or processes. This PVDF casefell into the latter group.

“Use of the internet typically offers fewer specifics for the client.
This means we would not be able to provide a clear-cut direction,”
he said. “Knovel Corrosion, on the other hand, gives targeted
literature references to support a probable cause of failure, whichsets the stage for engineers to make correct decisions and advise
the client on better material for applications.”
As Veolia has been involved in this challenging field for decades,
its engineers possess reference books and handbooks that help
them understand many of the problems their clients face. In
some cases, it is a race against time to solve a pressing problem.
Downtime at some plants can cost more than $100,000 a day.
That’s another reason why Esmacher appreciates the digitizationof the search process within Knovel and the speed at which his
team can cross reference various sources.
“Knovel Corrosion quickly gave us rankings for plastics inmany different environments, as material compatibility is notalways a simple yes/no answer. It also provided supporting casestudies to help explain our conclusions. I had never seen all
this within a single reference source before,” he said.

Esmacher explained that without the authoritative information
sources found in Knovel Corrosion, he would have had to rely
on internet searches. As well as generating too many hits —many from questionable sources — internet searches inevitably
end up on manufacturers’ websites which can be ambiguous,
added Esmacher.

Veolia uses Knovel Corrosion to pinpoint cause of valve failure3For more information about Knovel Corrosion,
visit elsevier.com/solutions/knovel-engineering-information/knovel-corrosion
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