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Is overplating really that bad?


Dave_P
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Italian cars of the 70's and early 80's rusted because of poor rust protection, not because of inferior steel.

I bought a new Alfa Romeo in 1981, but had it professionally rustproofed. It didn't rust significantly in my 6 year ownership (except for stone chips left untreated) unlike others of its kind.

By the mid 80's all car manufactuers were taking rustproofing seriously and it was longer possible to find 3 year old cars with rust holes in the villa for wings.

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36 minutes ago, Captain Pegg said:

Or perhaps the steel specification, treatment, fabrication and protection was rubbish. Automotive steels are used in very thin sheets in a very aggressive environment so need to be well specified and built.

I find it hard to see that you could produce a naturally fast rusting steel even deliberately. At the end of the day it's a lump of purified iron. There is a limit to how quickly it can rust naturally. On the other hand if you use the wrong specification, pare down the quantity to the bare minimum, fabricate it badly and protect it badly for the environment it will work in then that's a different matter. So I suggest rather like narrowboats the steel gets the blame because that's where's the symptoms are visible; but it isn't the cause.

JP

 

Sorry, but steel is not purified iron.

phil

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10 minutes ago, Phil Ambrose said:

Sorry, but steel is not purified iron.

phil

As I am sure you know steel is purified (and alloyed) pig iron, and as pig iron is technically an alloy of iron then so is steel.

For the purposes of my post it was just easier to make the point that ultimately we are talking about lumps of ferrous material.

Am I excused?

JP

PS - I reckon there is one other error in my posts above. (Caused by reliance on the internet over what I thought I knew and in hindsight I think I was right in the first place). Can you spot it?

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polish steel was what the owner stated.... But you are right about unknown usage I have a VW camper in Australia. No rust on the body at all at 12 years old. However 2 years ago I was getting in and the drivers step went through the floor... Localised rust. Looking at it in the the first 18 months it had been a hire van, and while I hadn't driven it on wet sand clearly someone else had as when I removed the step underneath was full of damp sand. Not noticed during services and there is no mot in Victoria...

 

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On 16/09/2017 at 18:50, Captain Pegg said:

No, for a couple of reasons.

First is that the biggest single source for the UK steel market is UK produced steel. After the UK comes the rest of the EU and overall the vast majority of the UK steel market is produced in the EU. Russia, India and China all import a small amount but one that is growing. One day it's conceivable that all UK steel will come from China and India but their share today is still a small minority.

The other reason is that steel is produced to an international standard and traded as an international commodity and does not significantly vary in standard.

Technical standards have changed in name and nomenclature from British to European to International but the basic composition and quality of the steel you can buy is pretty much the same as it has been for the past 40 years.

And if you buy it from a stockholder it's all 'British sourced'.

JP

 

 I think not, if you don't ask for British steel, complete with test certs ,  Itl be from India or China and full of lamination ,I weld pressure vessels to lloyds ,Dnv,ici,cornhill,British engine,national Vulcan,and other insurance company rules and regs,not one of them will accept Chinese steel , any way, why doesn't any one with a dodgy water line get it overplated  in stainless,3 MM is plenty ,and weld it with a 29/9 rod   Itl be just the same in 100 years ,crow.(peppermint pig)

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3 hours ago, Crow said:

 I think not, if you don't ask for British steel, complete with test certs ,  Itl be from India or China and full of lamination ,I weld pressure vessels to lloyds ,Dnv,ici,cornhill,British engine,national Vulcan,and other insurance company rules and regs,not one of them will accept Chinese steel , any way, why doesn't any one with a dodgy water line get it overplated  in stainless,3 MM is plenty ,and weld it with a 29/9 rod   Itl be just the same in 100 years ,crow.(peppermint pig)

Steel - including that from China and India - is a globally traded commodity. That is only possible with products that conform to an international quality standard. Lloyds Register most definitely have many approved Chinese steel producers - probably more than any other country - and a smaller number from India. Things have moved pretty quickly over the past 10 years in global steel supply.

Each company is however only assured for certain products and sizes so if you work in a specialised industry then such products may not be approved or perhaps imported. In my industry that's the case as we buy approx 100,000 tonnes a year of long product direct from British Steel at Scunthorpe and specialised rollings and castings from other EU suppliers.

For that reason I don't know what happens when you buy steel from stock as would happen for a narrowboat fabricator. Does the buyer get to specify and get the certificate of conformity to prove it? It's generally illegal to directly specify supplier within the EU in any case. Plus the fact that UK home produced and Asian imports only amount to 50% of the UK market so where is all the stuff from the EU and elsewhere going?

Genuine questions BTW.

I still stand by my answer to the original question. The origin of UK steel doesn't change enough from year to year for the overall quality to vary markedly even if there were significant variation in quality from different sources.

JP

 

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Well if I was a steel river/ canal  boat fabricator I'd be buying the cheapest plate going,as will everyone else,, is there any weld tests or any other stipulations required ,and is there any test certs required,or welder quals and  weld procedures needed to make a boat for river work,I wouldn't think so,is there any radiographs or ndt required to make and sell a narrow boat,if not there all going to be built cheap and cheerful ,some a bit better than others ,some making more profit than others,now my old springer is made of 3 MM hardox it's 35 years old and still 2.8 MM so it is all about the steel ,we used to make boilers out of  corten  .its like everything ,you get what you pay for and that Chinese monkey metal is what your getting nowdays, 

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8 hours ago, Crow said:

Well if I was a steel river/ canal  boat fabricator I'd be buying the cheapest plate going,as will everyone else,, is there any weld tests or any other stipulations required ,and is there any test certs required,or welder quals and  weld procedures needed to make a boat for river work,I wouldn't think so,is there any radiographs or ndt required to make and sell a narrow boat,if not there all going to be built cheap and cheerful ,some a bit better than others ,some making more profit than others,now my old springer is made of 3 MM hardox it's 35 years old and still 2.8 MM so it is all about the steel ,we used to make boilers out of  corten  .its like everything ,you get what you pay for and that Chinese monkey metal is what your getting nowdays, 

Johnathon Wilson only uses steel from the UK, Sweden and Germany he gets the certs and files them for the future

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'Is overplated steel really that bad?' Even if you have some misgivings what is the alternative? on an old boat with a tired and dated interior you might feel like ripping out the fit out and cutting out the old plating but its a hell of a job. If the fit out is perfectly ok then its a huge amount of work and expense to get back to where you started. The great thing with steel as opposed to wood is that you can weld a bit on, if you reject that as a means of repair then some boats are going to have a very short life.

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19 hours ago, Crow said:

 I think not, if you don't ask for British steel, complete with test certs ,  Itl be from India or China and full of lamination ,I weld pressure vessels to lloyds ,Dnv,ici,cornhill,British engine,national Vulcan,and other insurance company rules and regs,not one of them will accept Chinese steel , any way, why doesn't any one with a dodgy water line get it overplated  in stainless,3 MM is plenty ,and weld it with a 29/9 rod   Itl be just the same in 100 years ,crow.(peppermint pig)

Lamination was the term I was searching for, and relevant to the type of corrosion on the vehicles mentioned earlier- sheets of rust similar to mill scale, but unlike mill scale the sheets keep coming. 

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Curious, this. 

We have practical people in this thread talking about personal experience of lamination and other well informed people saying the steel quality cannot vary. 

In the world of plumbing we get pinholes in copper pipe occasionally, and in copper cylinders after many years of use. Something that should not be happening as corrosion resistance is the whole point of using copper.

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J Wilson  is the one to get a boat built by,  Itl be cock on with that plate,   I've just done a quick calc it's a bit approx but 40 ft x 6 ft boat at 10 tonn ish is only going to make a pressure of    Less than 1 pound a sq inch when in    the water,   a bean tin would hold more pressure,I think the only reason boats are getting thicker is to allow for corrosion allowance  on inferior plate,and if I was getting some over plating done on a big expensive boat I'd want tell tale holes drilling and tapping to fit a  scraider valve to pressurise and leak test the welds ,as if there's any pin holes or porosity to the parent metal waters going to get between them plates and that's the last thing you want Itl bulge and rot worse than ever

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