Strange Hole in steel roof

[swift1894]

I came across a strange hole in my 12 year old 6mm steel roof today. There has been a rust bubble under the paint work for a while, so I decided to rub it down. When I scraped off the paint I was amazed to find a hole all the way through the steel about 4mm in diameter. The steel wasn't actually rusty, there was a sooty black powder surrounding the hole! Anyone got any ideas what could have caused this?

[Scholar Gypsy]

That sounds a bit small for a radio aerial.

 

Whereabouts is it, and is there anything unusual on the inside?

[The Bagdad Boatman (waits)]

I would suggest that it is rust. Rust is not always red.

[MtB]

I came across a strange hole in my 12 year old 6mm steel roof today. There has been a rust bubble under the paint work for a while, so I decided to rub it down. When I scraped off the paint I was amazed to find a hole all the way through the steel about 4mm in diameter. The steel wasn't actually rusty, there was a sooty black powder surrounding the hole! Anyone got any ideas what could have caused this?

Yes. A 4mm drill.

 

[Keeping Up]

Where in the roof is it? Front, back, left, right, or what? Could it have been to feed a wire through, for an aerial or a solar panel?

[Nickhlx]

Good thing it wasn't in the baseplate !

[Loafer]

Yes. A 4mm drill.

 

 

Very witty Oscar! I shall award you a Greenie.

Strange though, for it to have been under his paintwork. Sounds like a bullet hole!

Edited March 10, 2015 by Loafer

[blackrose]

Perhaps someone filled it with something before painting over it and the filler has degraded.

[MtB]

Perhaps someone filled it with something before painting over it and the filler has degraded.

 

 

Yes. Probably made the filler from some spare sooty black powder they had lying around...

 

[swift1894]

I would suggest that it is rust. Rust is not always red.

The hole isn't exactly circular like a drill hole, and it wasn't put there for any cabling etc. I was there helping the welder when the roof was put on and he did a great job. I wondered if it could have been caused by a welding flash. Can't see how 6 mm steel could rust through in 12 years. The rest of the roof Is is excellent nick. It's a mystery.

[swift1894]

The hole is 1 inch in from the gutter but water doesn't gather there.

Edited March 11, 2015 by swift1894

[MtB]

The hole isn't exactly circular like a drill hole, and it wasn't put there for any cabling etc. I was there helping the welder when the roof was put on and he did a great job. I wondered if it could have been caused by a welding flash. Can't see how 6 mm steel could rust through in 12 years. The rest of the roof Is is excellent nick. It's a mystery.

 

 

There are deeper mysteries. Meaning of life? Is there a god? What makes women happy? Etc etc...

[swift1894]

There are deeper mysteries. Meaning of life? Is there a god? What makes women happy? Etc etc...

Agreed but this a canal orientated forum

[Loafer]

Lighting strike? Not sure it would do 6mm tho. Most cabin tops are 4mm. Are you sure it's 6?

[swift1894]

Lighting strike? Not sure it would do 6mm tho. Most cabin tops are 4mm. Are you sure it's 6?

Yes it's 6mm. I was there when it was delivered

[WotEver]

I would suggest that it is rust. Rust is not always red.

This ?

[swift1894]

This

 

???

[WotEver]

I was agreeing with Bagdad

[Mike Jordan]

I had a similar experience some years back with a new shell built from best quality german made steel.

A very small leak came from the centre of a roof plate with had been blasted and epoxy primed, only the windows and doors having been fitted.

On grinding away the paint in a small area I found that a ball shaped piece of some sort of slag ( 4mm Dia) had been rolled into the plate presumably during the making process. I was able to drill out the marble shaped piece and weld up the hole.

Only ever seen this once, but as mentioned above it could have been in the keel plate.

Mike.

[WotEver]

That sounds logical

[swift1894]

I had a similar experience some years back with a new shell built from best quality german made steel.A very small leak came from the centre of a roof plate with had been blasted and epoxy primed, only the windows and doors having been fitted.On grinding away the paint in a small area I found that a ball shaped piece of some sort of slag ( 4mm Dia) had been rolled into the plate presumably during the making process. I was able to drill out the marble shaped piece and weld up the hole.Only ever seen this once, but as mentioned above it could have been in the keel plate.Mike.

That sounds like what I've got. Can't think of any other explanation. I'm still puzzled by the sooty black powder though.

[kris88]

Carbon I would imagine

Regards kris

[onionbargee]

Black iron oxide. The skin that forms on steel plate after rolling, ie slag.

[PaulG]

That sounds like what I've got. Can't think of any other explanation. I'm still puzzled by the sooty black powder though.

Perhaps it was a rubber grommet that was used to plug the hole, then painted over.

12 or so years later it has perished away under the paint, leaving a black residue.

[Murflynn]

I had a similar experience some years back with a new shell built from best quality german made steel.

A very small leak came from the centre of a roof plate with had been blasted and epoxy primed, only the windows and doors having been fitted.

On grinding away the paint in a small area I found that a ball shaped piece of some sort of slag ( 4mm Dia) had been rolled into the plate presumably during the making process. I was able to drill out the marble shaped piece and weld up the hole.

Only ever seen this once, but as mentioned above it could have been in the keel plate.

Mike.

it may have been marketed as best quality but clearly it wasn't. Good quality control would include a scan to confirm no significant inclusions which clearly didn't happen.