Corrosion Control in the Wine Industry Mr Les Boulton WEA 2012 NZ
CORROSION CONTROL IN THE WINE INDUSTRY Les Boulton Nickel Institute New Zealand Consultant
WEA Conference Blenheim 6-7 September 2012
Winemaking materials – old and new • • • • • • • • •
Ceramics – over centuries Oak wood – over centuries Concrete with lining – 1920 Copper alloys – 1930 Cast iron – 1930 Galvanised steel – 1940 Aluminium alloy – 1950 Stainless steel – 1950 on Plastics – 1960 on
Stainless steel winery plant …
SS wine tanks
Stainless steel walkways, galleries and stairways
Stainless steel winery equipment …
Membrane press Stack vats Wine filter
Pumps for the wine industry …
Manufactured from cast and pressed grade 304 SS or grade 316 SS
What are the grades of stainless steel used in the wine industry ? • Define the service requirements • Evaluate the environment • Identify and select the right grade • 304 and 316 are the workhorse SS grades, but other grades may be used
Corrosion of metals in wineries … • Corrosion on a minute scale can result in contamination of wine • Bacterial sterility – chemicals employed for plant hygiene may be corrosive • Corrosion of winemaking equipment affects plant integrity and wine production
Contamination of wine due to corrosion … • Corrosion of steel – gives wine a metal haze – affects the taste, colour, aroma • Sulphur dioxide preservative – SO2 can be corrosive to metals - care needed in handling • Organic acids present in wine – tartaric, citric, malic, tannic, acetic acids - may be corrosive
Corrosion issues in wine industry… • Tartaric, tannic and citric acids are not corrosive at levels in grape juice and wine • Levels of sulphur dioxide may be problem in vapour space of wine tanks (ullage zone) 304 SS up to 75 ppm SO2 316 SS >75 ppm SO2 • Use of duplex tanks: 316 SS for tank ullage zone and 304 SS elsewhere on tank
316 SS
304 SS
Sterility and cleanability … o Product purity is critical in winemaking o Contact surfaces must be sterile and easily cleaned o Sterilising chemicals used can be corrosive, e.g. chlorine (Cl2)
Pitting corrosion due to poor CIP
o Clean-in-place (CIP) regime offers potential for corrosion
o Avoid extended residence time for cleaning chemicals
Stress corrosion cracking due to poor CIP
Corrosion and winery plant integrity… • Localised corrosion is the most common problem • Pitting corrosion and crevice corrosion can occur on SS • Stress corrosion cracking (SCC) is rare but can occur • Microbiologically influenced corrosion (MIC) during hydrotesting • Downstream consequences – possible contamination of wine
MIC in stainless steel tank due to contaminated water
Corrosion under insulation …
Stress corrosion cracking of 304 SS
SS hot water pipes leaked under insulation
Corrosion of forced air chiller in barrel room corrosion of copper due to sulphur dioxide - SO2
Fan Coil Unit
Barrel Room - sulphur dioxide gas used to sterilize oak barrels
Pinhole corrosion
Winery bottling plant … - Localised corrosion in 316 SS PLC valve - CIP cleaning introduced chlorides - Crevice corrosion in SS valve flange
Maintenance of winemaking plant … • Inspection – early detection of corrosion is critical • Review any previous failure records • Shutdown is time for inspection
• Inspect critical plant components first • Samples removed for further examination ? • Record inspection results
Weld decay in 304 SS vessel - detected during plant inspection
Repair of winery plant … • Permanent or temporary repair ? • Revert to original welding procedure • Pickle-passivate the weld repairs • Temporary repair - fill pits with epoxy filler • Polish surface after repairs • Avoid over-polishing repairs
Fatigue crack in SS weld due to over-polishing
Alternative materials usage in wineries… • Low-cost materials are used to replace 304 SS and 316 SS • Alternative materials include lower grade SS, plastics, and composites • Each material has its place in a winery • Winemakers must be satisfied that using an alternative material does not lead to corrosion problems
CONCLUSIONS … • Corrosion of equipment on minute scale can contaminate wine
• Sterility and cleanability of winery equipment are important • Contact with aggressive chemical cleaners can cause corrosion • Plant integrity affected by corrosion assess condition during shutdown • Corrosion damage to SS plant and equipment can be repaired
• Alternative material usage can present risks
CHEERS !
WEA Conference Blenheim 6-7 September 2012
Winemaking materials – old and new • • • • • • • • •
Ceramics – over centuries Oak wood – over centuries Concrete with lining – 1920 Copper alloys – 1930 Cast iron – 1930 Galvanised steel – 1940 Aluminium alloy – 1950 Stainless steel – 1950 on Plastics – 1960 on
Stainless steel winery plant …
SS wine tanks
Stainless steel walkways, galleries and stairways
Stainless steel winery equipment …
Membrane press Stack vats Wine filter
Pumps for the wine industry …
Manufactured from cast and pressed grade 304 SS or grade 316 SS
What are the grades of stainless steel used in the wine industry ? • Define the service requirements • Evaluate the environment • Identify and select the right grade • 304 and 316 are the workhorse SS grades, but other grades may be used
Corrosion of metals in wineries … • Corrosion on a minute scale can result in contamination of wine • Bacterial sterility – chemicals employed for plant hygiene may be corrosive • Corrosion of winemaking equipment affects plant integrity and wine production
Contamination of wine due to corrosion … • Corrosion of steel – gives wine a metal haze – affects the taste, colour, aroma • Sulphur dioxide preservative – SO2 can be corrosive to metals - care needed in handling • Organic acids present in wine – tartaric, citric, malic, tannic, acetic acids - may be corrosive
Corrosion issues in wine industry… • Tartaric, tannic and citric acids are not corrosive at levels in grape juice and wine • Levels of sulphur dioxide may be problem in vapour space of wine tanks (ullage zone) 304 SS up to 75 ppm SO2 316 SS >75 ppm SO2 • Use of duplex tanks: 316 SS for tank ullage zone and 304 SS elsewhere on tank
316 SS
304 SS
Sterility and cleanability … o Product purity is critical in winemaking o Contact surfaces must be sterile and easily cleaned o Sterilising chemicals used can be corrosive, e.g. chlorine (Cl2)
Pitting corrosion due to poor CIP
o Clean-in-place (CIP) regime offers potential for corrosion
o Avoid extended residence time for cleaning chemicals
Stress corrosion cracking due to poor CIP
Corrosion and winery plant integrity… • Localised corrosion is the most common problem • Pitting corrosion and crevice corrosion can occur on SS • Stress corrosion cracking (SCC) is rare but can occur • Microbiologically influenced corrosion (MIC) during hydrotesting • Downstream consequences – possible contamination of wine
MIC in stainless steel tank due to contaminated water
Corrosion under insulation …
Stress corrosion cracking of 304 SS
SS hot water pipes leaked under insulation
Corrosion of forced air chiller in barrel room corrosion of copper due to sulphur dioxide - SO2
Fan Coil Unit
Barrel Room - sulphur dioxide gas used to sterilize oak barrels
Pinhole corrosion
Winery bottling plant … - Localised corrosion in 316 SS PLC valve - CIP cleaning introduced chlorides - Crevice corrosion in SS valve flange
Maintenance of winemaking plant … • Inspection – early detection of corrosion is critical • Review any previous failure records • Shutdown is time for inspection
• Inspect critical plant components first • Samples removed for further examination ? • Record inspection results
Weld decay in 304 SS vessel - detected during plant inspection
Repair of winery plant … • Permanent or temporary repair ? • Revert to original welding procedure • Pickle-passivate the weld repairs • Temporary repair - fill pits with epoxy filler • Polish surface after repairs • Avoid over-polishing repairs
Fatigue crack in SS weld due to over-polishing
Alternative materials usage in wineries… • Low-cost materials are used to replace 304 SS and 316 SS • Alternative materials include lower grade SS, plastics, and composites • Each material has its place in a winery • Winemakers must be satisfied that using an alternative material does not lead to corrosion problems
CONCLUSIONS … • Corrosion of equipment on minute scale can contaminate wine
• Sterility and cleanability of winery equipment are important • Contact with aggressive chemical cleaners can cause corrosion • Plant integrity affected by corrosion assess condition during shutdown • Corrosion damage to SS plant and equipment can be repaired
• Alternative material usage can present risks
CHEERS !
