Rust patches or microbial / MIC?

[Alan de Enfield]

15 minutes ago, magnetman said:

Its pretty mental that someone found 22mm (7/8 inch) pits in steel from this. 

 

It was in the Hull & Bilges.

 

"Fresh Water" tanks were found with 'greater than' 10mm's depth of corrosion

[magnetman]

Jesus H Christ on a Jesus H bike ! 

Buy FRP boats ! 

 

 

[Mike Tee]

44 minutes ago, IanD said:

Is a vaccine being developed?

A gallon of IPA apparently- Phipps best used to do the job nicely 

[IanD]

3 minutes ago, Mike Tee said:

A gallon of IPA apparently- Phipps best used to do the job nicely 

So long as it's not Greene King... 😞

[Jamesl9]

Today a marina said if the hull is blasted with a high powered hot water/steam pressure washer before blacking the heat kills the bacteria, at least until the next blacking is due. A number of hulls on the marina had the MIC rust appearance/pattern just below the waterline except for the ones that were recently blacked. 

[Alan de Enfield]

6 minutes ago, Jamesl9 said:

Today a marina said if the hull is blasted with a high powered hot water/steam pressure washer before blacking the heat kills the bacteria, at least until the next blacking is due. A number of hulls on the marina had the MIC rust appearance/pattern just below the waterline except for the ones that were recently blacked. 

 

And as soon as a boat in the marina gets a deep scratch, those boats still afflicted can 'infect' the other boat as the 'confined' marina waters will be hosting the MIC.

 

The MIC will not be seen as it lives below the 'new blacking' and until it breaks thru no one will know that newly painted boat has MIC.

[Jamesl9]

7 minutes ago, Alan de Enfield said:

The MIC will not be seen as it lives below the 'new blacking' and until it breaks thru no one will know that newly painted boat has MIC.

I'm hoping that if the heat from the steam kills all, or almost all of the bacteria before blacking and is then blacked again a minimum of every 2 years it would hopefully keep the bacteria at bay enough so it doesn't cause to much damage. Also a good treatment with IPA at the same time as blacking.

[Alan de Enfield]

18 minutes ago, Jamesl9 said:

I'm hoping that if the heat from the steam kills all, or almost all of the bacteria before blacking and is then blacked again a minimum of every 2 years it would hopefully keep the bacteria at bay enough so it doesn't cause to much damage. Also a good treatment with IPA at the same time as blacking.

 

I hope you are correct - but - remember that the corrosion figures quoted in the table (>10mm and 22mm) are the depth of corrosion within 12 months.

 

DYOR !

 

I no longer have 'skin in the game' as I've sold up my steel boats and now just have GRP.

 

 

[john.k]

These bacteria are always present in wet soil and water .....Used to get an interesting effect on oil storage tanks that were installed on pumped river sediment (mainly sand) .....anywhere that a seashell touched the steel bottom,it would corrode a cavity in the 1" thick base ,eventually penetrating.......If you are interested in the subject of corrosion,there is a monthly magazine called "Rust".with all the latest research on the subject.

[DandV]

On 10/11/2023 at 16:56, blackrose said:

 

Ok, but what other colour would one expect in the bottom of bare de-rusted pits in steel? I once worked in a boat yard scurfing off the pitted steel interior of an old hull, getting to the bottom of pits with an angle grinder with wire wheels, a needle gun and a welder's chipping hammer. I never saw any other colour at the bottom of pits apart from silver.

 

I think people get into a panic about MIC without really knowing what they're looking at. It's a bit like how some people think they know what galvanic corrosion looks like in comparison to ordinary corrosion. Very few really do.

When you have very active microbial corrosion you need nothing more aggressive then the pad of your thumb to wipe off the black scunge,

( an Australasian term, for dirty sludge),  to reveal, more intense white, then polished silver, metal, that would almost instantly start dulling and turning iron oxide orange. 

2 hours ago, john.k said:

These bacteria are always present in wet soil and water .....Used to get an interesting effect on oil storage tanks that were installed on pumped river sediment (mainly sand) .....anywhere that a seashell touched the steel bottom,it would corrode a cavity in the 1" thick base ,eventually penetrating.......If you are interested in the subject of corrosion,there is a monthly magazine called "Rust".with all the latest research on the subject.

You and I have seen the same stuff.

[Alan de Enfield]

1 hour ago, DandV said:

When you have very active microbial corrosion you need nothing more aggressive then the pad of your thumb to wipe off the black scunge,

( an Australasian term, for dirty sludge),  to reveal, more intense white, then polished silver, metal, that would almost instantly start dulling and turning iron oxide orange. 

 

Or similar if it has developed the crusty 'rusticle'.

[ditchcrawler]

When I cast off this morning I noticed this on the piling, I hope I haven't caught anything 

 

[magnetman]

Someone told me that the moss growing at the waterline is a sign of serious issues and my boat was going to sink within weeks.

 

I think they were taking the mic.

 

 

 

[Jamesl9]

The surveyor I was talking to said around 85% of the boats he survey's have MIC and it's almost unavoidable these days. He also said it's easy to keep it under control with isopropyl alcohol without having to shot blast the hull back to metal. When the hull is pressure washed before blacking it will remove all of the rusticles, once the hull has dried it needs to be sprayed with isopropyl alcohol all over and especially where the rusticles were and this will kill the existing bacteria instantly. The isopropyl alcohol evaporates/dries within 5 to 10 minutes and it can then be painted with bitumen blacking as normal. If this is repeated every 2 years when blacking it should stop any new rusticles that may form from causing to much damage.

[magnetman]

I like the word 'rusticle'.

 

 

Never seen one on a canal boat

 

https://en.wikipedia.org/wiki/Rusticle

Apparently there are also bacteria which eat Nylon !

 

Clever beasts

 

https://en.wikipedia.org/wiki/Nylon-eating_bacteria