Welding a petrol tank

**jellywrestler** · 13th August 2009, 21:17

Originally Posted by XRVrider

Ta Jelly, hey did you get my pm to you regarding the Nzeta's? .

Hey; are we on first name basis now? i'll take them into a copy shop and get them done, as they're foolscap pages and my scanner thingy is only A4

**XRVrider** · 13th August 2009, 21:25

Sorry Mr Wrestler

Thats great, ta for copying, like I said before just name your price, will send you a cheque, not a rubbery one. I got a couple of questions for you, just in regards to your bikes and what you did to em... and what one is worth when done up... I've no idea. Also I'm a grovelling bee-arch but got any interesting/hard to find spares?

**XRVrider** · 13th August 2009, 21:32

Originally Posted by LBD

Plroblem with water can be the cooling effect and if it gets a little warm you get steam expanting coming out of the weld buggering up the integrity of the weld. The strength of the weld can also be affected with rapid cooling.

Wash with water then purge with inert gas is the only serious and reliable option.

Ta LBD

I just gotta whip around one stud on each, should be quick so hopefully not too much steam. If so I try the inert gas way. Didnt think of that though, ta for the info.

**LBD** · 13th August 2009, 21:34

Originally Posted by XRVrider

Ta LBD

I just gotta whip around one stud on each, should be quick so hopefully not too much steam. If so I try the inert gas way. Didnt think of that though, ta for the info.

Studs For?

Sealed with a Gasket?

Do you need to weld them?

**XRVrider** · 13th August 2009, 21:41

Yep there's no way around it. They are Nzeta tanks that have 4 studs that bolt the tanks down onto the body.

The studs are stupid as they actually go up inside the fuel tank a wee bit, so when these have broken out/pulled out they leave an 8mm hole. They are welded onto thicker metal patches that are welded onto the tank from new, so they pull out of the patch. Spose they were thought up 50 odd years ago, so go figure.

**LBD** · 14th August 2009, 03:21

You have thought it out obviously...You restoring an old bike?

Out of interest, what is it?

**XRVrider** · 14th August 2009, 09:25

They (2 of) are Nzeta's. You might know them, but google search Nzeta in images for how they are supposed to look.

**Firefight** · 14th August 2009, 10:17

have been to a few of these that gone wrong over the last 20+ years in my the job, but would imagine they are the extreme events, I know that work shops do this all the time, with no problems. some good info posted so far.

have a look at these links

http://www.mig-welding.co.uk/forum/s...ead.php?t=3818

http://www.mig-welding.co.uk/forum/s...ead.php?t=6056

there poms, but it still of interst.

I did it myself a few years ago, just filled the tank with water as close to the top , put on the cap inverted the tank(tipped it upside down) and then braized (sp?) the hole, when done hooked a hose line to a warm air fan dried tank out ..

had a fire esxtingusher handi

Firefight

**imdying** · 14th August 2009, 10:29

Originally Posted by sparkles

put it on the end of a car exhaust and let it dry out some hours

Originally Posted by Ixion

Forget water. Gas purging is the only safe way.

Carbon monoxide FTW!

**LBD** · 14th August 2009, 15:04

Originally Posted by XRVrider

They (2 of) are Nzeta's. You might know them, but google search Nzeta in images for how they are supposed to look.

Of course...I did not recognise the name but put the CZ in front...

Did the NSU look similar?

Good luck with the project.

**XRVrider** · 14th August 2009, 15:28

Ta LBD. There are a few bikes that look similar but having the tank over the front wheel is the unique thing. The headlight is directly in front of the tank so some say the detonator and bomb are right together ha ha. Despite this there have been no reported explosions from Nzeta or Czeta riders.

Anyway Ive mangaed to put off til tomorrow what I could've got done today, so have procrastinated perfectly, and the pub has got in the way. Reports of hopefully avoiding explosions will have to wait til tomorrow.

**XRVrider** · 15th August 2009, 16:13

All good, job done. Filled with water and brazed one stud in on the best tank, the other has rust inside and thin metal in spots cos of it. So that one's a almost a throw away. No problem with the water filled method tho.

Flushed both tanks throughly with water, and blew the car exhaust through them for 10 minutes. Dont know weather it helped, but the petrol smell inside the tank was much less after this. Filled them with water and brazed and welded with seemingly normal results. All went as if it was just another welding job.

Ta for the advice given here guys.

**_Shrek_** · 15th August 2009, 16:26

Originally Posted by XRVrider

All good, job done. Filled with water and brazed one stud in on the best tank, the other has rust inside and thin metal in spots cos of it. So that one's a almost a throw away. No problem with the water filled method tho.

Flushed both tanks throughly with water, and blew the car exhaust through them for 10 minutes. Dont know weather it helped, but the petrol smell inside the tank was much less after this. Filled them with water and brazed and welded with seemingly normal results. All went as if it was just another welding job.

Ta for the advice given here guys.

it's coz you put the car exhaust through that you had no problems, it gets rid of the fumes that would other wise explode