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ASTM A690 steel sheet piles

In lots of marine projects in Latin America, clients nominate marine sheet piles. and lots of clients ask for ASTM A690 sheet piles. And we have products many steel profiles in such steel grade.
What is A690 steel grade. Below you can find the mechanical properties and chemical compositions of it.

Mechanical Characteristics
Material Yield Strength Tensile Strength Elongation
A690 ≥345 Mpa ≥485Mpa ≥21


Chemical Composition
C Si Mn P S
≤0.22 ≤0.4 0.6-0.9 0.08-0.15 ≤0.04

After half a century, there are many varieties of steel can be selected. The United States Army Corps of engineers do not recommend the use of A690 in any of its engineering. Steel corrosion is related to neutral water and oxygen, and its reaction formula is Fe+H2O+1/2O2→Fe (OH)2; the produced Fe(OH)2 continues to react with oxygen and turns into "iron rust" composed of FeOOH, Fe3O4 and non-crystalline substances after the combination with or separation from H2O.They recommend light steel material in the low tide zone and splash zone with paint.

Note that although the A690 is a high model steel sheet piles, but its strength is medium level. The reaction through which steel is turned into "iron rust" proceeds under the effect of galvanic action. If your building is not in the water or the marine environment, more than 50 of the materials can replace ASTM A690 and ASTM A572 If you are building in seawater, but the steel sheet pile immersed in seawater, the ASTM A690 statement does not have the advantage.

If you are not familiar with the corrosion calculation, you may need to read some articles about rust and corrosion. For various reasons, there are innumerable ultra-fine anodes (positive poles) and cathodes (negative poles) on the surface of steel that forms a local cell. Just using the A690 steel does not necessarily extend the service life of the steel sheet piles. When you understand this point, you will find other solutions for engineers to save a lot of time and money for their customers. If you work in the marine environment, you should read the following truth: A690 does not necessarily increase the steel sheet piles in your life, and not the best choice. And it has high price and low availability.

The ASTM statement says only in seawater splash zone, A690 has better corrosion resistant ability. than A36 and A328. Fe at anode of local cell is dissolved, and reduction reaction of oxygen occurs at cathode; therefore, corrosion reaction could continue.
Whether or not containing copper, A690's atmospheric corrosion resistance ability is essentially a lot better than ordinary carbon steel.This kind of steel is especially in the "splash zone" which reflects ordinary carbon steel (specifications for A36/A36M and A328/A328M) .In the splash zone,it is exposed to rain and wind or solar or both with the drying process.

USA Army Corps use the EM-CR-1.6:A690 statement in the seaman steel sheet pile.
Unless the building is in salt water (sea water) or alkaline water with high yield strength of steel, or in the splash zone and atmosphere,A328 should be used with protective layer of the steel sheet piles.