S-BT Threaded Fastener Specification

Specifications page91
S-BT Screw-in threaded studs
Neutral salt spray test
S-BTstudswithduplex-coatingare
subjectedtoaneutralsaltspraytest
accordingtoDINENISO9227.
Underthistest,thecorrosionresistance
ofS-BTstudswithduplex-coatingis
signicantlyhigherascomparedtohot
dipgalvanized(HDG)systemswithat
least45µmcoatingthickness.Grade
A4stainlesssteelS-BTstudsremain
stableunderthistestandwithstand
corrosionduetopassivesurface.
Cyclic corrosion test
Thecycliccorrosiontestgivesamore
realistic assessment of corrosion
resistanceundernaturalenvironments.
Underthistest,thecorrosionresistance
ofS-BTstudswithduplex-coatingis
comparableandevenhitherthanHDG
systems.GradeA4stainlesssteelS-BT
studsalsoremainstableunderthis
cyclic corrosion test.
Test results
OntheS-BTstudswithaluminumsealingwashernocorrosionwasfound
after12weeksinthecycliccorrosiontest.Allaluminumsealingwashershave
adequatelysealedthedrilledholesoverthetestperiodoftime.Therewasno
visiblecorrosionintheboreholes.
Conclusions
•IntheISO16701test,thematerialcombinationofaluminumsealingwasherand
theduplex-coatingofthecarbonsteelS-BTstudshasbeenfoundtobeoptimal.
•After12weeksinthecyclicclimatechamberthecoatingsystemofthecarbon
steelS-BTstudsshowednotendenciestocontactcorrosion.Thecombinationis
suitableforuseinC1,C2andC3environmentacc.DINENISO9223:2012.
•Nocorrosionwasfoundinthedrilledholes.Thisisstrongevidencethatthe
sealingwasherprovidesaneffectiveseal.
5.10.4 StainlesssteelS-BTstuds
General comments
TheS-BTstainlessstudsaremadefromtheduplexstainlesssteeltype1.4462.
ThisgradeofstainlesssteelisclassiedascorrosionresistanceclassIVaccording
toDINEN1993-1-4:2015,whichmakesthematerialsuitableforaggressive
environmentslikeincoastalandoffshoreapplications.Themicrostructures
ofduplexstainlesssteelsconsistofamixtureofausteniteandferritephases.
Comparedtotheausteniticstainlesssteelgrades,duplexstainlesssteelsare
magnetic.ThesurfaceoftheS-BTstainlesssteelfastenersiszincplated(anti-
frictioncoating)inordertoreducethethreadformingtorquewhenthestudis
screwedinintothebasematerial.
TheHiltiX-BTsystemwasdevelopedbyHiltiCorporationespeciallyfor
applicationsonsteelstructuresthatformpartofoilandgasproductionfacilities,
inshipbuildingandingeneralsteelconstruction.Thereforecomprehensive
corrosiontests(electrochemcialtests,eldtest)havebeenperformedonthe