Change in law for pressure treated lumber means that most
non-stainless fasteners will
degenerate very quickly
The EPA has set December 31, 2003 as the deadline for the last production of
pressure treated wood using copper chromated arsenic (CCA) for residential
use.
Newly developed Arsenic Free treatments including alkaline copper
quaternary (ACQ) and copper azole (CA) contain approximately 6 times more copper
than CCA. In long term corrosion testing conducted by the Forest Service
division of USDA on fasteners used in CCA treated wood, only stainless steel
nails and screws exhibited virtually no visual signs of corrosion and negligible
weight loss over a fourteen year period while fasteners made of galvanized steel
and aluminum showed significant degradation. These results illustrate that
stainless steel is your best fastener choice. A brief explanation of
galvanic corrosion reveals the reason why.
Galvanic Corrosion occurs when dissimilar metals are in contact with each
other in the presence of an electrolyte. In the galvanic series chart
shown below materials higher up on the list will corrode more rapidly when
paired with materials further down it. The degree of corrosion increases
as the separation of the metals in the list is increased. Thus, when
exposed to water, the electrolyte, stainless steel used to fasten copper
impregnated wood is far more resistant to corrosion than fasteners made of
steel, zinc coated steel or aluminum.
GALVANIC SERIES OF METALS AND ALLOYS
ZINC
ALUMINUM
MILD STEEL |
LEAD
BRASS
COPPER |
SILICONE BRONZE
MONEL 400
304 STAINLESS STEEL |
316 STAINLESS STEEL
SILVER
PLATINUM |
Conclusion: To be sure your fasteners will last as long as your (ACQ)
or (CA) PRESSURE TREATED lumber,
select your needs from one of our 4 stainless fastener web sites. All the sites
use the same shopping cart to enable you to buy all your needs during one
shopping trip.
Stainless nails,
screws etc - Stainless
collated fasteners - Stainless
Hinges - Stainless
Bolts
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