Buy a cartridge of Sikaflex 221 or 227 from Bunnings - under $20. Sandpaper around the area, make sure it is dry and then apply a good bed of Sikaflex over the area and then stick a thin piece of tin/aluminium or even thick plastic over the Sikaflex. Leave for a few days and it will be stronger than the original. The tin/alum/plastic over the top makes the patch stronger.
Use the leftover Sikaflex for 'whatever'.....it sticks/seals anything. It has been used to form suspension bushes in emergencies.
If you try to seal it with a soldering iron you are never guaranteed that it will not fail in the future.
Good Luck.

ps...Sikaflex is not silicone but polyurethane.

Dare I say it, I was fixing a cupboard to a lower inside wall of a bed in my campervan and misjudged the length of the screws.

To cut a long story short, the screws went right through the wooden panel and it looks like two of them have pierced my black plastic water tank which was fixed flush up to the wooden panel on the other side under the bed.   Looks like it will be a job and a half to get the tank out for repair, so haven't had a good look yet, luckily the tank was empty, otherwise the van floor would have been flooded.  

I did think of the tank earlier, but thought it was further down under the bed and didn't check (yeh, I know...Duh).

So back to my original question, does anyone know whether these black plastic water tanks can be welded please???

  

Hi Duh

I have done something similar.

I Drilled the hole out to the size of a rubber cork, (Clark Rubber sell then in tiny sizes particularly for plugging holes) put a little bit of silicone around the cork, tap it in the hole and, hey-presto, job done.

Hope this helps.

Mark

That's what I love about this forum and it's members, such a great lot of talent!!!!

Thanks to all of you for your suggestions, I'm sure any one of them will work for mine.

I'm looking for a midget at the moment, one end that I can get at only has a single screw bracket that I can get at ok, but the other end is deep inside the cavity holding the tank and only has a midget size entrance to get at the screwed bracket on that side.  I think it might have been put in when building the van. 

I took out the two offending screws and replaced them with short screws that will not protrude, would have to have done that eventually anyway.   I'm not game to fill it up yet with water to see how bad the puncture is as I don't want the van flooded or the flooring affected, I only use the water for hand and utensil washing, carry my own drinking water. so not a great drama.

The side that is pierced is hard up against the board the screws went though, I'll put a couple of pic's up later so you can see what I mean, in the mean time I'm peed off with a certain individual (me) for being so careless..... 

As stated by Legendts many plastic car parts are welded with a heat gun & a filler rod, but with so many different types of plastic  it could be a gamble.

I would go with the sikaflex, this is what they use to fit windscreens in cars with & now available in a small tube, rather than the cartridge.

Be carefull not to get it where you dont want it as it sticks worse than s#!t to a blanket. LOL.

JC.

GaryKelly wrote:

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You're right about the depth of talent here, Vic... including you when you get outta bed on the right side hehe.

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 Exponential Brain Power

Thanks again for the comments and help.

Here is a couple of pic's of the tank, one from the back of the vehicle and the other from the inside hatch, it looks like it is roomy in there but it is not, just an illusion.  As said earlier, the back bracket is ok to get at, but the front (hatch bracket) access is in a long way and restricted by the hatch size.   If you look in the photo's you can see two screws protruding through the timber on the side that butts up to the tank and just above it.

They are the screws at the top of the cupboard I fitted outside, what cannot see are the two screws at the bottom of the fitted cupboard which I believe would have punctured the tank when they came through.   I have since replaced them with shorter screws, but a bit late after the event, but will avoid the problem again if and when I repair the tank (depends on time and whether I use it in the near future).

Hi Duh

Having seen the pictures and now understanding the proximity of the lower screws that we can't see, here's what I would do if tank removal is not an option.

Assuming of course that you have punctured the tank, which, looking at the screw size is higly likely, there's not a lot to lose.  So, get yourself a spade bit

Put the pointed of the spade into the lower screw hole and drill.......... VERY GENTLY............ until the wood is removed and the plastic of the tank is exposed, yes the screw hole in the tank will be bigger now, but you now have access and space to do something with the hole.  For me it'll still be a rubber plug or looking at the tank, I'm thinking that a puncture repair plug may just do the job.  The hole is already there, all you have to do is put a plug into it.  A puncture repair kit will cost around $25, a rubber cork about $1  Once repaired put a patch over the hole in the cupboard.

Thanks for the suggestion Mark, worth thinking about.

It just occurred to me that if I can reach and disconnect the hoses (bracket at that end would be more difficult) at the hatch end, I should be able to remove the bracket at the rear end leaving the difficult bracket in place and slide the tank out from the rear end.

If I can't remove the hoses I should be able to cut them and rejoin them later......

It will be a lot easier to inspect the tank and fix it if it is out of the vehicle.

That's be a lot better Duh.
Initially it was muted that you couldn't get the tank out, if you can, that's the way I'd be going for definate.
Good luck.

Mark

Mark wrote:

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That's be a lot better Duh.
Initially it was muted that you couldn't get the tank out, if you can, that's the way I'd be going for definate.
Good luck.

Mark

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 Yeh it hadn't dawned on me that I only had to remove one bracket from one end and then (hopefully) be able to slide it out, unless there is something hidden holding it in I can't see (like some adhesive on the bottom etc to stop it moving).   I'll keep you posted on what I find etc.

Thanks Mark!

Superglue won't really work for you Vic but the Sikaflex will. You need some bulk and superglue doesn't have it. If it has definitely not punctured the tank even silicone would do. Even the patch idea would work using Sikaflex to fill the cavity first.

Just thought even plastic filler should work or even car bog may take to it.

This is what i use to repair plastic tanks kayaks & any thing else plastic. Itsa a modified old soldering iron, reshaped the copper tip & pressed a piece of flared copper tube into the tip. This is used to feed plastic strips into the repair. I cut up different types of plastic in to strips to use as feed stock for each different type of plastic. Plastic welding if done properly is usualy a good repair. Also a list of diferent types of plastic i found some where on the net.

Thanks very much for that DeBe, according to your chart PE Polyethylene is used for RV water storage tanks, are far as symbols go there is a number 2 (but not in a triangle) on my tank which seems to indicate High Density PE Polyethylene as also used for wheelie bins.

It says to use Polyethylenes Rod or Fibreblex, and the note "Applying Filler or Painting is nearly impossible".....

I manage to remove my tank (had to cut the hoses to get it out, couldn't get to the hose clamps or other bracket, too far in).

The good news is, the screws I put in didn't puncture the tank, but the drill I used for one of the screw holes nearly did, no puncture to the tank).   There is a shallow hollow in the tank where the drill bit bored out a small cavity, I am hoping I can just use something in the cavity to give it a bit more strength to the plastic where that is.  Any ideas of what to use?  Could I use superglue or something similar?  Look for the small cavity indentation in the photo (only one).

After I have resolved that I will either have to buy some more drinking water (food quality) hose to replace the other hose entirely or get some joiners for where I cut the hose.  Some sort of silicone or something (white) has been used around the hoses where they go through the floor.  One hose is used to fill the tank, another for the sink hand pump, and the other an overflow pipe for when the tank if full.

What about silicone Jeff, I have some on hand, do you think that would be ok ???

Thanks blaze, sounds good, will use that.   Hope your neighbours have gone.......

Vic you won't need drinking water safe will you as you haven't penetrated the tank? Still reckon your Silicone would do the job.

Sorry I didn't get back earlier as my subscription is not contacting me.

edit no wonder still had my work email as contact.....DUH! No not you Vic.

Hmmmm......went to Bunnings, they sold me Black Sickaflex Pro which is drinking water safe which they said would do the job.

On reading the fine print (with my glasses AND a magnifying glass) it said "Will Not adhere to Polyethylene, Polypropylene or PTFE ".

According to the earlier chart it appears the type of plastic used for my water tank is Polyethylene ???????

So looks like it's back to Bunnings.     

Thanks Mark, Silicone it is.   Lucky I hadn't opened the Sikaflex tube I bought so will take it back to Bunnings for a refund!

All I have to do is find my Silicone now, it's somewhere, just have to remember where I put it!  

When at Bunnings today, the just happened to be a Selley's Rep there doing there display.   I explained to her what I need the stuff for and she recommended Selleys Knead-it Epoxy Putty to repair the tank indentation  http://www.selleys.com.au/putty/epoxy/knead-it-aqua/  it can be used safely for fish tanks, underwater repairs and suitable for fresh and salt water among other things and it says it is safe for contact with drinking water.  So bought a 50g container of that.

Reading the fine print on the back of the packet the Knead-it comes in and it said "Not for Teflon.  Use Selleys Plastics Glue for Polyethylene or Polyproplene" and my tank appears to be Polyethylene.  Might give the Knead-it Putty a go and see what happens.  The link for the Selley's Plastics Glue is http://www.selleys.com.au/adhesives/household-adhesive/quick-fix-adhesive/plastics-glue/ 

Decided to go with the putty http://www.selleys.com.au/putty/epoxy/knead-it-aqua/ seemed to adhere ok, just waiting for it to dry out now to see if it falls out (I hope not).

If it stays put ok, I was thinking of sticking a bit of cloth tape over the putty repair as an extra precaution.   Might sound like overkill, but easy enough to get off again if I have to, but will leave it in place if ok.....

Thanks Jeff, will do that and leave in place over the small patch.....

Just to finish off the thread, filled indentation with putty, when dried put a "cross" of cloth tape over it for extra support, tested with full tank of water (and used Milton liquid to clean tank at the same time) no leaks, tank emptied and refitted tanks and hoses to Transit....