Dipping a chassis to remove the galv?

[tobes]

Can anyone suggest the correct procedure for removing the galvanising from a galved land rover chassis? I presume its possible by dipping it in some form of acid?

I have a 90 with a galvanised chassis that I have hacked about and needs a rebuild, as I cant afford a new chassis at the moment (and this one has been galvanised from new) I was hoping to get it stripped to bare metal, do the work and then worry about the re-finish later on.

[Maverik]

Can anyone suggest the correct procedure for removing the galvanising from a galved land rover chassis? I presume its possible by dipping it in some form of acid?

I have a 90 with a galvanised chassis that I have hacked about and needs a rebuild, as I cant afford a new chassis at the moment (and this one has been galvanised from new) I was hoping to get it stripped to bare metal, do the work and then worry about the re-finish later on.

Best thing is to talk to the guys that galvanise the chassis' in the first place (e.g. Richards chassis uk), they'd be the most likely people to help you.

You can remove the zinc by immersion in dilute hydrochloric acid, the acid is converted to zinc chloride in the process - this is the method for small bits of zinc removal - this is a pretty toxic and dangerous method, but the only one i believe. Once it has been dipped in acid you'll have to paint it or something as it will be totally free of oxides and will start to corrode just sitting there in the air - could also have some problems with the box sections holding onto the acid, it will need to be flushed or neutralised well, you might have to drill some holes in the box sections to help drain the fluids... but as you wont be able to coat the bare metal inside the box sections chances are they'll start to corrode quite badly if not treated.

Now i chassis is quite big, could be costly as if the zinc is as coated as thick as it is on my chassis then it will take quite a while for it to be dissolved.

In summery, not sure the whole process will do your chassis much good, and factoring in the Faff, probably cost you more than just getting a new chassis, sell the one you've got, put it towards a new one - someone will no doubt want it.

Hope that's some help

Mav

[mobyone]

why do you want to remove the galvanising in the first place. you can weld straight to galv, arc moreso than mig. the zinc coating will come off in the pool as you weld.

besides that, you can remove it with a good sanding wheel aswell. if you mean inside the chassis rails, like you say, worry about treating it after you have done the stuff you intend on doing. you can even use a grinding/cutting disk to remove it then if it is really deeply 'cut' you can put bracing where you hacked about with it.

and dont forget, the acid dip will attack your chassis (how much depends on alot of things) anyway, so you might have less than you started with.

i would say mechanically remove it where you need to then do fabrication to whatever, then passivate or at least paint over the welds, then when funds allow it you can have it regalvanised.

i have welded with a stainless steel spoon as the filler before, just depends on what you are welding to what.

regards

richard

[lrfarmer]

a chassis is dipped in hydrochloric acid before it's galvanised but holding it there longanuff to get the galvanise off may take most of the chassie with it

buts bet i'd say if grind the galv off were you need to weld

[mobyone]

to add to my last comment, obviously it was stainless which i was welding with the spoon as filler and not a galv'd chassis. i was just using it as an example in as much as welding with galvanised steel is not an issue if you are using mild steel rods/wire.

use a mask and try not to breathe in the fumes from the galv'd steel as it will give you a harsh sore throat and flu like symptoms for a few days.

richard

[ChrisM_110]

As ^ arc welding, especially with the [expensive] dissimilar rods is pretty successful. I've seen it done, not tried myself yet. Some cold-galv primer once the welds are tidied will last until you're ready to re-galv.

[Ex Member]

Just grind the areas you need to weld first. You need to do that regardless. It is best not to weld over the zinc due to the fumes and the weld contamination.

[lrfarmer]

Just grind the areas you need to weld first. You need to do that regardless. It is best not to weld over the zinc due to the fumes and the weld contamination.

yes! zinc poisoning is not very good for you.

[tobes]

My thinking behind dipping it was that I intend to weld large areas , often in the fiddly places where th grinder cant get, and I didnt know if I would then have to re drill all the holes after its secong galving..... I was looking for the easy option!

[landroversforever]

places aren't going to like re-dipping a chassis that has old glav on it...

[pinny]

i would go for shotblasting using chilled iron shot this will remove galv we used to do a lot when i worked as a shotblaster

[bishbosh]

Getting the galv properly removed will probably cost more than a decent second hand chassis I would expect.

If you can't get to bits with the grinder, then get yourself a powerfile (and a job lot of belts as it eats them for a past time)

[matt bristol]

re Welding Galvanised metal

I ws told that if you weld galvanised metal it gives off Cyanide gas, which is meant to be bad for your health, no idea of the chemistry behind this as its a long time since I left school but best to grind it off prior to welding just in case

[mobyone]

if you are on a tight budget, you only need to make sure the thing is really clean. ideally grinding down to good steel first. but you can get very good proprietry solvents, even acids that you paint on, remove x amount of time later and then clean/prep before fab starts. welding alot of galv is not a problem in as much as from a good metal bond point of view. if you use a well ventillated area, outside for instance and go for it you will not have a problem welding the full length of the chassis.

on a side note tobes, if you really do have a lot of welding to do. be wary of the fact that your chassis will warp if you don't brace it, or do tacks up the rails first. and if you weld it outside, i would suggest stick welding as with mig, your gas will almost certainly blow away and leave you with a really pap and pourus weld.

if you decide to do it yourself and have any q's regarding the welding pm me and i will help you out.

--- and i believe welding gas produced is not cyanide, it is basically a weak acid which can/does cause some irritation --- wear a good mask and a wet tea towel under your mask if you wanna get really cheap. but it is fairly safe to weld indoors with a few open windows/doors at the very least.

inverters are better for newbie welders of the arc type. however,good arc welders (300amps and a.c) can be bought for about £45 from second hand and just look at ebay for new prices. totally affordable. go for a good rutile stick aswell, as you can weld up even exhaust manifolds with these type of rods.

richard

[TD5 power]

hi

the gas produced is vaporized zinc which re acts with the air to make zinc oxide (white powder) inhaling this will give you flu like symptoms but go away after 48hrs and current research believes no harmful damage is done. There is also a small 0.9% max amount of lead which vaporizes at a much higher temperature so should be less of a problem.

One of the better quality dust masks from B and Q etc should be ok, but i would still recommend welding outside and trying to keep out of the fumes as much as possible. Have a look at this for welding Galvanised steel

I don't think it matters what type of arc welder is used, the technique is the same but you get a very different feel when welding with an inverter compared to a conventional welder. I was taught on 300amp oil cooled sets which could go all day and i prefer them to inverter type, however the inverters are still good for welding on site.

mobyone did you mean 300 amps single phase in your post above not AC? A stick welder can not be alternating current or is that an inverter set (arc and Tig)which is very good value at £45

Using good quality electrodes and keeping them dry can make a lot of difference, but make sure you use the correct type rutile is good for general steel work and will be fine for your chassis but not to get a good quality result on an exhaust manifold (depending on material).

Matt

[mobyone]

ok, so to save on confusion, i meant you can buy a single phase ac arc welder that can go up to 300 amps for £45. infact there are several on ebay now for less. inverters are much more tame beasts to weld with. neater,cleaner and just easier to weld with. but they are like £200 plus new, but there is a murex 135 inverter on now for £50. about 14 hours to go till auction end.

i would say you need at least 160 amps to get decent enough penetration as lets not forget it is structural rigidity were playing with. and yes, good rods make the world of difference. stick 'em in the oven for an hour at about gas mark2-3. warm rods are dry for a start, but weld easier too. and if you get thicker rods, you get more current when welding and so more heat....

td5, single phase is ac, so is three phase. the only difference is single is 240/110, three phase is either 205 or 415 depending on the setup.

regards

richard

[TD5 power]

sorry i thought you were referring to the welding current output type as the only welder to have AC out is some tig sets my mistake:ph34r:

I only used an inverter set (murex Tig set up for arc) for a short time at college. It could produce good results however ive spent a fair amount of time with oil cooled units so i may be a little biased, i believe there is little to choose between them.

with 160 amps on a land rover chassis i think you'll be blowing holes, its only 3mm thick depending on what and where is being welded i would go for 2.5 (90amps) or 3.2(120amps) rods as a rough guide. Try on an off cut first and adjust to suit your style and the job.

Matt