Huck® BobTail® Coatings

Huck BobTail large diameter LockBolts have gained the prestigious Allgemeine bauaufsichtliche Zulassungen (German national technical approval) from the world renowned DIBt (Deutsches Institut für Bautechnik) for use in both static and dynamic applications in civil engineering.

Joints fastened together by BobTail large diameter Huck LockBolts, within the range specified [DIBt Approval Newsletter], are maintenance free. Furthermore, the approval concludes that re-torque/ re-tension of an installed Huck BobTail LockBolt is not possible and also not necessary and connections do not require maintenance regarding preload.

Whilst Alcoa Fastening Systems do not offer a specific corrosion guarantee for each of these coatings, we are able to show through extensive testing that the following figures can be expected. All testing was carried out by an independent 3rd party testing facility at Institut für Korrosionsschutz (Institute for Corrosion Protection) Dresden.

SuffixPartCoating Thickness
(minimum total)
ColourCorrosion Resistance UninstalledDIBt Approved
J43Pin12 umRaSilver/Grey720 hours without base metal corrosion 
J44 Collar10 umRaSilver/Grey720 hours without ferrous corrosion 
J45Pin15 umRaSilver/Grey1440 hours without base metal corrosion Yes
J46Collar15 umRaSilver/Grey1140 hours without ferrous corrosionYes
J57Pin16 umRaSilver/Grey2000 hours without base metal corrosionYes
J58Collar14 umRaSilver/Grey2000 hours without ferrous corrosionYes
J64Pin20 umRaBlack1008 hours without ferrous corrosion 
J65Collar12 umRaBlack1008 hours without ferrous corrosion 

All finishes are free from hexavalent chrome and compliant with European directive EU 2000/53 Annex 2 in materials and components of vehicles.

For more information visit [BobTail Webpage] or contact:

Alcoa Fastening Systems

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