Aluminium and Dangerous Thermite Action?

The use of iron or steel and Alluminium is a bad idea at the best of times if it is at sea it is even worse! The ther-mite reaction is fairly unlikely but not impossible. Ther-mite is an intimate mixture of iron oxide and alluminim powder normally ignited by either a ribbon of magnesium or an oxyacetylene torch, it is extremely exothermic and reduces the iron oxide to molten iron. The possibility of having the exact conditions of the precise gas concentration and the right circumstances for a dangerous spark at the same time while never totaly impossible are how ever rather unlikely. It would be best if the points of contact were illiminated where ever possible by a plastic insulator or suitable air gap. In normal circumstances the alluminium will form a good layer of oxide coating by its self and this will have to be sraped away by the impact and it will have to be warm if not hot and dry for a spark to be made between the two metals. These conditions are most unlikely in the north sea areas. Having your hands freeze to a hand rail in winter is much more of a risk. The reaction between salt and the two metals producing an electric current is a very minor risk. (Electrolylitic action) If you are really concerned consult a safety advisor.

why mention it in the Ex guidelines?

EINSTEIN SAID THAT IMPOSSIBLE WAS A WORD USED ONLY IN THE DICTIONARY OF FOOLS!

A few other problems

The combination that you suggest will create an RF re-transmitter. Any radio-frequency transmissions in the area will be accumulated by the rail amplified and retransmitted at the railing. This will make it unsafe and expose workers to high levels of radiation. To prevent this ground cables are required at every post.

Aluminum makes great antennas,.... and will attract lightning

Yes they can be bonded by a seperated means.

The thermit process is used to weld railway rails together in the field. The reaction is very spectacular, and for quality control purposes it has to be carried out by appropriately trained personnel.

A skilled crew of 2 persons can prepare the alignment, weld the rails and dress a joint ready for use in under 2 hours.

Powdered aluminium is used in the mix, as only in powdered form does the aluminium have enough surface area to complete the reaction. The materials are supplied pre-mixed in plastic bags as there is a risk of moisture getting in and reducing the quality of the weld. The reaction crucible needs to be pre-heated by using a gas jet, probably propane, so as to drive off moisture. Initiating the reaction itself is an art and a wonder to behold: a 'fuse' of magnesium metal is used to start it in anger, partly to generate enough heat to get it to go, and partly to give the unfortunate operators a chance to run away upwind!

In comparison, the use of solid aluminium structures close to steel ones is a relatively safe thing to do.

Aluminum is weird stuff, though we take it for granted in everyday life. You know those safety matches that won't light on anything except the striker pad... Try dragging one quickly along an aluminum rail and see what happens.

As for thermite reactions, though, I think this might be highly unlikely. While thermite consists of three parts aluminum powder and 11 parts iron oxide, it takes 3,000 degrees to get the thermite reaction going. Hence the reason why burning magnesium is used to get it started. If this sound dangerous to you, so be it. But, again, the operative word here is "powered" aluminum.

Hi vermin, When I was younger we used to mix aluminium powder and sodium chlorate together to make an explosive. Spencer.

Yeah, that's pretty close to the flash powder that they use in barrel bombs and cherry bombs. Burns fast, doesn't it. Still got your eyebrows?

"Has anyone out there got any concerns regarding the use of aluminum handrails and aluminum ladders on a new gas plant?" In a word, NO!

Calling Chicken Little. Calling Chicken Little.

"The sky is falling, the sky is falling!"

The "Thermit" reaction is high temperature and spectacular BUT it is not going to happen with aluminum hand rails and structural element without some very unusual circumstances and coincidences, e.g. special additional chemicals and intense ignition source.

Caustic Soda (NaOH) solutions and powdered aluminium react strongly exothermically to form sodium aluminate.

Manufacturers of aluminium saucepans advise their customers not to use Caustic Soda near them on safety grounds, though with solid aluminium the risk is small. The user is usually unaware of the above reaction, which is an important demonstration item in school inorganic chemistry classes. Aluminium, like many other metals, forms a protective layer of oxide fairly quickly when a fresh surface is exposed to air.

Yep. Yep. Yep.

The possibility of a spark from aluminium and rusty steel is taken into account in breathing apparatus design to reduce the risk of a spark from impact of any external exposed part of the apparatus striking other exposed metal. Either an aluminium cylinder striking a rusty steel object, or a rusty steel cylinder striking an aluminium object.

This might cause a spark (but I even doubt that), but the "thermite" reaction is really hard to get started. The two reactants need to be powdered, and it takes a hell of a lot of heat to get it going - 3,000°. I think that's a lot hotter than any house fire.

The only place I could see being concerned about rusty iron and aluminum smacking together would be in an explosive atmosphere.

IF YOU HAD TAKEN THE TIME TO ACTUALLY READ MY POST THEN YOU WOULD HAVE SEEN THAT THIS WAS REGARDING A NEW GAS PLANT!!!!!!!!!!!!! IF THIS AINT A HAZARDOUS ATMOSPHERE THEN WHAT IS????????????????????????????????????????

AFTER ALL THIS PLACE IS GOING TO PROVIDE BRITAIN WITH 20 % OF ITS FUTURE GAS NEEDS FOR THE NEXT 40 TO 50 YEARS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!11

Don't holler!!!

OK. If it's that much of an extreme environment, you're talking a whole bunch of exotic materials that won't spark. Any steel-to-steel blow can cause a spark, that's why in flammable environments they often use brass tools.

Even within a power plant such as this, I assuming you're not walking around in methane all day, considering you'd be dead, and if there's a sudden catastrophic leak, I'm guessing a point of ignition will be found way before you can clear the area, much less get your emergency equipment on.

My only point here is I'm not certain a "thermite reaction" is any worry. But, try it for yourself... Go find a really rusty piece of steel out there, and drag a piece of aluminum across it and see what happens. I'm guessing even a strong impact can't generate enough heat of friction (or whatever) to even make a spark.

One last thing, by rereading your original question, I'd say you're pretty much screwed. If there's that much aluminium around and a "thermite reaction" can occur, how does one control a working environment like that?! Better make everyone leave their car key at the door. That's not counting the rusty, old, high carbon drill bit a worker left in the back three years ago.

It is a mystery as to why Zone 1 areas are so large in some hazardous area assessments: they usually indicate a serious material containment problem or a perception of same.

It sounds as though this particular plant would do well to sort out its containment problems first, for safety as well as economic reasons. In comparison, the risk caused by the presence of aluminium is way down the list. "The only free thing is a source of ignition".

Another question worth asking is why the poster is taking up this issue on CR4 with no indication that it has been passed through the operating organisation's safety specialists for local review and assessment? Surely that is the correct priority? With anonymity assured in most cases, and little incentive to take action, CR4 contributors aren't going to correct the perceived problem, even if they could stop typing long enough to do so....

PLEASE READ MY FIRST POST AND YOU WILL DISCOVER THAT IT WAS THE SPARK CAUSED BY THE IMPACT THAT I WAS INDEED REFERRING TOO AND NOT THE WELDING OR SOME OTHER CREATION OF A HIGH TEMPERATURE. iT IS THE SPARK CAUSED BY THE THERMITE ACTION UPON IMPACT WHICH HAS ENOUGH POTENTIAL ENERGY TO CAUSEE AN EXPLOSIVE GAS IN THE RIGHT CONCENTRATIONS TO IGNITE.

SOME PEOPLE DO NOT READ EVERYTHING BEFORE COMMENTING IT IS ALWAYS BETTER TO DO THIS AS IT PREVENTS YOU MAKING MOUNTAINS OUT OF MOLEHILLS!!

It was my understanding that dragging aluminum across rusty steel that was dangerous. Not the other way round.