Corrosion at a Concrete Plant

[waterguyMN]

I have a corrosion issue that you may be able to help me solve. I work for a water treatment company and I work with a concrete plant that uses a humidification chamber (75'x75'x25') to cure concrete blocks. While curing, these blocks are stored on "pallets" that are 3'x3'x1" steel plates. These plates are corroding at an alarming rate (days). The cost to replace these plates is considerable so we have been looking for a way to retard the corrosion to get prolonged life from the pallets. We have concluded that the cause of the corrosion is the availability of oxygen and the humidity in the chamber. We looked into the VCI technology but the size onf the chamber makes this solution unfeasible.

Any suggestions?

Thank you

 

[StephenA]

Have you tried the corrosion forum? I was wondering if you could use Cathodic Protection.

 

[BigH]

Why use steel? Have you considered other materials for the plate?

 

[dbuzz]

Cathodic protection may be the way to go if you don't want to replace the plates en masse. That said, CP is not necessarily inexpensive.

Suggest through that as you do replace the pallets you consider alternative materials of construction such as stainless steel or fibre-reinforced plastic? Presumably wood would be no good in a humidification chamber.

 

[waterguyMN]

Thank you for the suggestions.

dbuzz Please explain how cathodic protection would work as the plates are racked up separately and there shouldn't be any electrical conductance???

We contemplated alternative materials but we "need" steel to support the weight of the blocks...

Any additional suggestions are appreciated.

Thank you

Brad

 

[dbuzz]

I'm no CP expert, however I expect that you would protect your plates by connecting cabling to the plates and applying a current, changing their electro-potential and reducing the rate of metal dissolution. Probably not a cheap solution.

For an alternative material of construction you might consider fibre-reinforced grating, which is often used as flooring in minerals processing and industrial plants where corrosion is a significant issue
(

http://www.webforge.com.au/access_products/frp_grating.php).

However, I don't know whether it would be suitable for your application.
- What are the plan dimensions and thickness of the plates?
- Do the plates span one or two ways?
- What loads are the plates subject to?

 

[StephenA]

My original thought was either an anode fixed to each plate to save on the linking problem, or hot dip galvanising or zinc spraying.

I suggested the corrosion forum because with fresh water there may be better materials than ordinary zinc.

Have you thought of fusion bonded epoxy and then a rubber/ PE mat to protect from abrasion?

 

[bimr]

This was posted several weeks ago in a different forum but seems to have disappeared. Now, you have it posted in multiple forums.

You need to have these chemicals in your water treatment water treatment arsenal:

http://www.na.graceconstruction.com/product.cfm?mode=c&did=6&id=52

If you do not want to use the chemicals, consider switching to aluminum or stainless steel pallets. Galvanizing would probably work, but as the panels are scraped, you would get a higher level of corrosion at those scraped points.

Catodic protection is not going to be feasible because you would have to wire moving pallets.

 

[StephenA]

Individual anodes clamped to each pallet would obviate the need for an impressed current. Submarine pipelines do this all the time.