Leaks in an ETP (Effluent Tank ) 1

[eski1]

Hi
We are having trouble with a couple of Effluent Tanks where holes are appearing in the Large Mild steel Tanks as per picture below.
These tanks are 5m high and are 4 panels high and its only the top panel that seems to be a problem and only in certain areas around the tank.
We are trying to understand the reason for the issue only appearing in certain areas and any steer on this would be appreciated.

Also apart from a complete panel replacement does anyone have any ideas on how to best overcome the issue even in the short term until a longer term panel replacement can happen

 

[bimr]

It looks like typical corrosion of steel at the air/water interface. The higher concentration of oxygen at the interface contributes to corrosion.

Bolted steel tanks also have thinner walls than welded tanks which makes for a shorter service life.

Microbial action has been identified as a contributor to rapid corrosion of metals:

MIC

Without a lining, the steel will rust through quickly. Does this tank have a lining? Is there any turbulence in the tank? Tanks where the water is quiescent have more corrosion.

 

[eski1]

Hi Bimr

Many thanks for the answer , that makes perfect sense from what you have said.

 

[JedClampett]

Short term, hang a 40 mil HDPE liner in front of the holes. the water pressure will hold it in place.
Bolted tanks are supposed to have a lifetime warranty. They should provide you a replacement plate gratis.

 

[bimr]

Never seen a lifetime warranty.

Some steel tank companies offer warranties up to 20 years which sounds exceptional; until you read the fine print. Warranties which include only a single element of the bolted tank and do not cover the cost to have the part removed, shipping costs or the labor to re-install are really not much of a warranty. The cost of a new seal is minuscule compared to the downtime or labor required to replace the seal. In addition, it is tough to trust a company which is only a few years old or a new startup to be around long enough to honor the warranty when it is needed most.

Many of manufacturers have a “tail light warranties”. The warranty is good as long as you can still see the tail lights of the tank erectors.