2.0 MODULAR SUPPORT TECHNOLOGY 2.4 CORROSION
Modular Support Systems Technical Guide, Edition 1
The following is an overview of typical finishes used on Hilti MT products. For more detailed information from Hilti on material finishes and corrosion protection, please consult the Hilti Corrosion Handbook which can be found under the Documents section for MT portfolio items on Hilti Online.
CORROSION HANDBOOK
12 / 2021
Outdoor Coating( OC)
The Hilti MT OC System for outdoor applications has been developed with various corrosion protection technologies and consists of two finishes: Hot-Dipped Galvanized( HDG) and Zinc Magnesium( ZM). The Hilti OC is intended primarily for use in environments considered Outdoor with low pollution. For more corrosive environments, additional protection may be required. The proper amount of corrosion protection for a given application should always be assessed by the Design professional to ensure products meet the project requirements.
Hot Dipped Galvanized( HDG)
Electro-Galvanized( EG)
Electro-Galvanized, or zinc plated, bonds a minimum 0.5 mil zinc coating to carbon steel through an electrolysis process. Most Hilti MT connectors and miscellaneous hardware are available with an electro-galvanized finish. This coating is in accordance with DIN EN ISO 2081.
Pre-Galvanized( PG)
Pre-Galvanized parts are manufactured by passing sheet steel through a molten zinc bath. Afterwards, the sheets are cold-formed into applicable shaped profiles and slots are punched, hence the name“ pre-galvanized ". PG refers to pre-galvanized parts with punches slots and PGS refers to solid strut. Surfaces of the punched and cut portions are partially protected by the adjacent zinc plating which acts as a sacrificial anode impeding corrosion of the raw edges. However, if corrosion remains a concern additional protection may be required. PG conforms to ISO EN 10346 galvanizing, with a Z275 thickness( 0.787 mils thick or 0.77 ounces zinc per square foot of steel).
Component parts such as base plates and system connectors have zinc coatings applied by the hot-dipped galvanizing( HDG) process in accordance with the ASTM A153M Standard. On hot dipped galvanized parts, the zinc coating process occurs after cold forming and punching. The parts are pretreated, pickled, and then dipped into tanks of molten zinc. HDG provides increased corrosion resistance compared to PG and EG finishes. HDG conforms to ASTM A153 / A153M galvanizing as stated on the product sheet for beams, connectors, bases, splices, and fasteners. Suitability of a HDG finish for a product must be assessed for each project.
Zinc Magnesium( ZM)
MT profiles such as strut, channels, and girders are coated with zinc-aluminum-magnesium alloy( ZM) by a continuous hot-dip galvanizing process during the steel coil phase in accordance with the EN 10346 Standard. On Zinc Magnesium parts, the process involves sheet metal coils that are drawn continuously through a bath of molten zinc after the surface has been cleaned and it is subjected to a special annealing process. In addition to zinc, the molten bath contains Magnesium( Mg) and Aluminum( Al). The Aluminum reacts with the steel surface to create a layer with a thickness of 0.984 mils per side( 1.02 ounces per square foot), which inhibits the formation of ZnFe phases. Hilti’ s OC ZM processing conforms to the EN 10346 Galvanizing Standard.
2023
20