corrosion of buried steel 1

[fattdad]

different soils, different position of the water table, different codes (IBC, AASHTO, etc.). What are the critical soil properties to document the extent to which buried steel will corrode? I know that folks claim 1/4 in! Sure, but. . .

Is it just pH and conductivity? I'm okay getting those values for soil. Am I missing anything?

Kind regards,

f-d

ípapß gordo ainÆt no madre flaca!

 

[SlideRuleEra]

See National Bureau of Standards (NBS) Monograph 58 "Corrosion of Steel Pilings in Soils".
The above quote comes from the Summary on pages numbered 21 & 22.

http://www.SlideRuleEra.net

 

[BridgeSmith]

I think the availability of oxygen is also a factor. Black steel gas lines are direct buried all the time, but they're buried deep enough there's not enough oxygen for rust to form.

Edit: Ah, beat me to it SRE.

 

[SlideRuleEra]

HotRod - Posts 1 minute apart, I'd say that is simultaneous. You are right about piping, such a problem that the Ductile Iron Pipe Research Institute (DIPRA) has a procedure to deal with it... polyethylene encasement: Link

http://www.SlideRuleEra.net

 

[MTNClimber]

Water municipalities have us test the soil for moisture content, chlorides, resistivity, pH, and redox potential. I couldn't tell you how each one affects the corrosivity of the soil. I know the lower the resistivty, the higher the corrosivity (see below). Typically there are special consultants (not us) that take those values and recommend a corrosion protection system for the water systems, if warrented.

Other than that, I may have seen the oxygen concentration affect steel H-piles on a highway project. We wanted to re-use the piles which where driven in the 1960's. We exposed the upper portion of the piles and they were more corroded in the fill layer (higher oxygen concentration) versus the natural glacial out wash layer (supposedly less oxygen concentration vs. fill)... or the fill just had a lower resistivty. Either way, there isn't a great way to test for oxygen concentration.... is there?

 

[fattdad]

The oxygen aspect makes perfect sense. Hadn't thought of chloride or redox as discrete tests. So, thanks for that! I'll have to further google.

I'm also curious if layering has any effect. Like layers of peat, organic silt, sand, fat clay, etc. Do these act battery-like and generate current flow through the steel element?

I'm in the midst of a thought process. Thanks to all!

f-d

ípapß gordo ainÆt no madre flaca!

 

[BUGGAR]

zinc rich soil?

 

[Settingsun]

The images below are from Australian Standard AS 2159 "Piling - Design and Installation". Beyond these parameters, I'd suggest specialist advice rather than trying to self-educate unless the risk is low.

 

[fattdad]

So. . . there's a microb test?

f-d

ípapß gordo ainÆt no madre flaca!