Rust patches or microbial / MIC?

[Jamesl9]

Evening, this boat has been out of the water for 24 hours. Wondering if these are normal rust patches or microbial/biological corrosion.

[Alan de Enfield]

 

It looks very much like MIC.

Knock off the rust and see if the pits are 'silver' in the bottom.

 

MICROBIOLOGICAL-CORROSION.pdf

 

 

 

 

 

 

[Jamesl9]

7 minutes ago, Alan de Enfield said:

 

It looks very much like MIC.

Knock off the rust and see if the pits are 'silver' in the bottom.

 

MICROBIOLOGICAL-CORROSION.pdf

 

 

 

 

 

 

Thanks. That's what I suspected, the pits although very shallow are silver. I've been told it can be treated easily by high pressure blasting the hull, then spraying with isopropyl alcohol, then reblacking. I can't find anything about this online, have you ever heard of treating MIC this way before?

[Tracy D'arth]

11 minutes ago, Jamesl9 said:

Thanks. That's what I suspected, the pits although very shallow are silver. I've been told it can be treated easily by high pressure blasting the hull, then spraying with isopropyl alcohol, then reblacking. I can't find anything about this online, have you ever heard of treating MIC this way before?

Bleach wash is said to work. Small pits do look like microbial.

[Alan de Enfield]

42 minutes ago, Jamesl9 said:

Thanks. That's what I suspected, the pits although very shallow are silver. I've been told it can be treated easily by high pressure blasting the hull, then spraying with isopropyl alcohol, then reblacking. I can't find anything about this online, have you ever heard of treating MIC this way before?

 

The link I attached explained the 'normal' way of killing it off - the problem can be if you don't get it all, it continues to live beneath the 'good paint' and just spreads.

 

Treat it whilst you can - in the early days of MIC (the 1960s) it was found in a ships bilge where it pentrated 8mm of steel in under 2 years.

It is only recently that the UK Inland waterways industry has started to accept that MIC is a 'thing', those discussing it have always been accused of 'crying wolf' and saying the 'sky is falling in' but, finally they are beginning to be proven correct.

 

If a hull is found with evidence of microbial attack, it is necessary to deal with it to try to prevent it recurring. A simple solution is for the whole area to be washed with copious amounts of high pressure fresh water. When dry the area affected should be coated with a strong bleaching agent (sodium hypochlorite) diluted 1:4 with water and left for twenty four hours. Afterwards a second high pressure fresh water wash is necessary followed by recoating. This will probably remove around 90% of the microbes but the only real solution is to blast back to bare steel and to treat any inaccessible areas such as tack-welded rubbing strakes as best one can with the bleach solution before applying the next stage of the coating process. The main problem is that the microbes can continue to live beneath the existing paint coatings and once sealed in with a fresh blacking, the lack of oxygen and light is the perfect environment for them to thrive leading to a risk of corrosion from the inside out. No coatings are entirely proof against a microbial attack from the exterior. Minute pinpricks, mechanical damage below the waterline are all opportunities for the microbes to penetrate the steel and commence the process from the outside in.. WARNING SODIUM HYPERCHLORITE IS HIGHLY CAUSTIC AND TOXIC. IT MUST BE TREATED WITH GREAT CARE AND RUBBER GLOVES, WELLINGTON BOOTS AND EYE SHIELDS ARE ESSENTIAL.

Edited November 9, 2023 by Alan de Enfield

[system 4-50]

HYPERCHLORITE?  hypochlorite?  We need to panic about bleach? I would recommend keeping it in bottles, not wellington boots.

[Peanut]

Using a flame gun to raise the pit temperature to something above 200°C would most likely kill all of the microbes. Most Ikely denature their organic structure or turn them completely to ashes. 🙂

[blackrose]

9 hours ago, Alan de Enfield said:

It looks very much like MIC.

Knock off the rust and see if the pits are 'silver' in the bottom

 

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.

Edited November 10, 2023 by blackrose

[system 4-50]

There must be somebody on the forum with the time and facilities to set up an experimental galvanic corrosion test on a piece of boat-type steel with several different standard coatings and report back in a year's time?  Any volunteers?

A MIC test might be a bit hard to set up.

[MtB]

2 minutes ago, system 4-50 said:

There must be somebody on the forum with the time and facilities to set up an experimental galvanic corrosion test on a piece of boat-type steel with several different standard coatings and report back in a year's time?  Any volunteers?

A MIC test might be a bit hard to set up.

 

Very droll!! 

 

[Alan de Enfield]

4 hours ago, 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.

 

Yes, I'm sure that after "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."

 

The difference is that MIC forms a sort of scab - 'pick the scab off' and you have 'a silver pit', no wire wheels, no needle gun and no welder's hammer.

 

Type 2 (read previous link) actually deposits a silvery coating, it is not the actual boat steel.

 

Often closely associated with the gallionella species, thiobascillus ferro-oxidans is a sulphur oxidizing bug (SOB). This leaves a similar pit to the gallionella species but with vertical stepped sides and the flat bottom covered with a hard silver-white substance. The latter is tetra hydrated ferrous sulphide and is non-toxic. It appears not to rust but will eventually start to discolour.

Edited November 10, 2023 by Alan de Enfield

[Slim]

13 hours ago, Jamesl9 said:

Thanks. That's what I suspected, the pits although very shallow are silver. I've been told it can be treated easily by high pressure blasting the hull, then spraying with isopropyl alcohol, then reblacking. I can't find anything about this online, have you ever heard of treating MIC this way before?

That is exactly what I was told by a surveyor last year. Isopropyl Alcohol.  It isn't that expensive either.

[Mike Tee]

If you are a smoker, don’t while using IPA unless you want to do a Joan of Arc impression 

[Jamesl9]

12 minutes ago, Slim said:

That is exactly what I was told by a surveyor last year. Isopropyl Alcohol.  It isn't that expensive either.

No, it's only £20 per gallon online and 2 to 3 gallons is enough for the entire hull. Does it permanently get rid of the MIC thought or at least stop it for 3 years until it can be sprayed again during the next blacking?

[Alan de Enfield]

8 minutes ago, Jamesl9 said:

No, it's only £20 per gallon online and 2 to 3 gallons is enough for the entire hull. Does it permanently get rid of the MIC thought or at least stop it for 3 years until it can be sprayed again during the next blacking?

 

Surely if it is active underneath the existing coating, spraying it with IPA will do nothing.

[Jamesl9]

9 minutes ago, Alan de Enfield said:

Surely if it is active underneath the existing coating, spraying it with IPA will do nothing.

That is one of my concerns. The recommendation is to first clean with an ultra high power pressure wash then spray with IPA, then apply new blacking. I'm not sure if IPA can get/absorb through any left over bitumen blacking or not, it may be able to.

[Alan de Enfield]

4 minutes ago, Jamesl9 said:

That is one of my concerns. The recommendation is to first clean with an ultra high power pressure wash then spray with IPA, then apply new blacking. I'm not sure if IPA can get/absorb through any left over bitumen blacking or not, it may be able to.

 

I think if I had MIC, I'd be doing the job properly (to ensure it was all removed) and having the hull 'sand blasted'

Knowing how quickly it can perforate a hull ** I wouldn't want to wait 3 years to see of it had, or hadn't killed it.

 

I was reading a scientific article last night and it showed examples of how destructive MIC can be, the worst case they came across was that MIC caused pits 22mm deep in 1 year.

 

 

 

[john.k]

IPA can only kill whats in situ when its sprayed on .......it has no residual effect ............High pressure water blasting (30,000-60,000psi) will clean steel to white metal....( the clean metal will flash rust) .....however ,it produces no profile ,so doesnt aid coating adhesion.

[Mike Adams]

All this stuff about MIC  is interesting. Is there any scientific test for presence of the microbes? What I have failed to find out if hot zinc spraying works as a preventive? My hull was shotblasted, hot zinc sprayed aand epoxy coated a few years ago. I assume if will kill them off but will it prevent future action?

[Alan de Enfield]

14 minutes ago, Mike Adams said:

All this stuff about MIC  is interesting. Is there any scientific test for presence of the microbes?

 

Yes, Microorganisms are present & it produces 'by-products'. Whilst you may not 100% of the time find the 'by-products', if you do find the 'by-products' then you do have MIC

 

In the table I posted above 

 

 

You can see that there were 3 examples of MIC where no by-products were detected, but it was confirmed by finding the Microorganisms present.

 

 

 

14 minutes ago, Mike Adams said:

What I have failed to find out if hot zinc spraying works as a preventive?

 

 

From my readings, if it has been totally removed, pretty much any coating prevents re-infestation, BUT, the slightest scratch or chip down to 'bare steel' can result in re-infestation (assuming MIC is in the water where the boat is) and it then works itself along the steel and under the coating.

Edited November 10, 2023 by Alan de Enfield

[Cheshire cat]

Have a look at any of the locks between colwich and Stoke on the Trent and Mersey. There seems to be plenty of mic on the steelwork. It seems to me any boat navigating the canals is going to catch a dose at some point.

 

Presumably when moored up you unknowingly pass it on.

[Mike Tee]

social distancing might work

[IanD]

2 minutes ago, Mike Tee said:

social distancing might work

Is a vaccine being developed?

[Alan de Enfield]

4 minutes ago, IanD said:

Is a vaccine being developed?

 

Yes -  Its called 'Bleach' & Trump has already undertaken the testing phase, he didn't get MIC so its 100% successful.

[magnetman]

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

 

I assume from the description that this may have been the interior of a boat with vegetation growing in it. 

 

Keep oily bilges I say. 

 

Mad news. 

Edited November 10, 2023 by magnetman