I've checked all the local scrap yards with emails and they're all out. Could be a road trip in a few weeks for personal visits to the rest.
On the off chance I mailed Lion Nathan directly, but I think I'm pushing my luck there :o)
I've had an idea to possibly get a water boiler tank (180lt Rheem), cut it in half, use the bottom (with the element) as the boiler and the top half upside down as the mash tun.
I'm no plumber but I saw a discussion about this on Aussie Home Brewer a while back*.
There was some mention of "sacrificial anodes" which I think is some metal which corrodes faster than copper. Being that it's easily corroded, there's a danger** that stuff would leech into your liquor.
Might be worth a look on there to see what they say
* My recall is a bit hazy on the upshot
** The degree of danger is a whole other question.
Simon,
Before I scored my keg from the offsales over the road (via their brewery rep) I phoned the Speights guys down South and they called me bacck a couple of weeks later to offer me a keg or two, which I didn't need any longer. But they do flick the old kegs off from time to time so it is worth a call - but I'd suggest with thee larger breweries that you phone them rather than email to get to chat to someone who knows.