Whenusingrubber for gasketor seal purposes one should take into account
that corrosion problems can occurbecauseof the following reasons:
∑ Ingressof liquidscontainingchloridesundergasketsand sealscan lead to a high
chlorideconcentrationand lead to severecorrosionproblems(stainlesssteel).
∑ Degradationof the adhesive usedto locate the gaskets.
∑ Degradationof rubber by productor cleaningagents.
15.6.4 Adhesives and sealants
Whenthe use of adhesivesis required (e.g.for labelling),the recommended
choices are (in random order,the preferences willdependon the areaof
application)givenin Table15.5.Adhesives that are not in direct contactwith
product and not in the contactarea in principledo not requirespecialapproval.
They shouldbe easyto clean and resistantto the chemicalsand temperatures
occurring withintheirimmediate installedenvironment.
The use of sealants in electricaland controlinstallationsis generally to avoid
potentialsoil traps.For example, where the practicalsolutionrequires the wall
mounting of a cabinethavingseveral cablesterminated to it, the wall-cabinet
outer perimeter surfaces should be sealedwitha foodstandard siliconsealant to
prevent a soil trap beingcreatedat the rear of the cabinet.
15.6.5 Surfaceroughness of constructionmaterials
Froma hygienepointof view,the surface roughness or surfacefinishof
constructionmaterialsis veryimportant.Tests haveshownthat the cleaning
Table15.4 Elastomers
Preferredelastomers Commontrademark
Siliconrubber Silastic
Nitrilerubber Perbunan
*Naturalrubber
Nitrile/butylrubber NBR/H.NBR
Fluorelastomer Viton
Polychloroprene PerbunanC
- Mostfrequentlyused.
Table15.5 Adhesives
Preferredadhesives Commontrademark
Single-partepoxies(ESP108,ESP110) PermaBond
Anaerobicadhesive(A 131) PermaBond
Anaerobicadhesive 518 Loctite
Siliconesealant Common
260 Handbookof hygiene controlin the foodindustry