Good Evening all. I hope the title is self explanatory - there are quite a few threads around the forum which describe this issue. Please may I open a discussion on the subject to try to get to the bottom of it? There is no doubt that it happens, here are some threads which have gone before. Tilley vapourizers burst often in kerosene operation?? Tilley Vapouriser Failure Bialaddin 320 disaster I am not sure that any of these really got to the base of the issue (credit of course to all contributors - please add more comments here) We know some things about bad lamp behaviour with these types - bad fuel, pressure, enlarged jets and bad mantles -but I don't think these can cause a vapouriser to fail by swelling or becoming "pregnant". Some are related perhaps, vapouriser is already worn out, but I don't see them as a root cause to swelling up and failure. I have posted in various places my dear old (grr!) X246B dated 1164. Yes I know they are reckoned to be LOD PARC (anag) but they must have worked sometimes - for a while at least. Mine has consumed very many parts, much more than it originally cost to buy - so how come? Tank &valve were clean and OK. But vapourisers are not cheap - and it would eat them up in not so many hours. Did I fit bad parts - I don't think so - all good sources. Or is it more subtle than that? I begin to think it is. First is the cleaning rod. That can be too long as it comes supplied new. If you assemble it to the control cock and it is tight at the pricking position (overall length is too long and it it pressing hard against the jet orifice when needle is in up position) when it is hot it will punch through the jet. I had one do that in a Cornish field - uncontrollable flames & scrap. A temporary rescue was possible by some peening - but long term that vapouriser was scrap. So on next attempt the cleaning rod was very carefully fitted by filing to length, just right. This one worked for quite a long while (24hrs burn in several sessions) then it dimmed and was obviously in trouble. Here we go again.... Swollen and stuck in spigot. I have still not managed to remove it - bah - more scrap- but why? Plenty of carbon build up in the tube - after only 24hrs elapsed running - strange? Could it be the fuel - I discount that - it was not diesel? Lately (see the posts under Worried about CPL!) I changed the burner and vapouriser / mantle together. What a transformation! It is brighter than it has ever been but so far I can't say much so far except it has done 4-5hours burning faultlessly. I knew my old burner had an issue with the internal ridge which contacts the upper rim of the vapouriser - that won't matter I thought. Not so sure now. Before the vent and glass position were determined by the fact they were sitting on the external cage. Now they come to rest on the vapouriser and gap to the cage rim is some few mm below. The handle pegs can only just slot back in to lock it down. That is different to before. I reckon vapouriser swelling and bursting is more about running much too hot due to lack of conduction cooling of the vapouriser to the burner body. Old Tilleys and the like sat the burner directly on the vapouriser. Other later designs make that contact doubtful depending on how the parts are assembled. A much too hot vapouriser will mean weakened strength of the side wall tubing and also more likely that fuel will crack to carbon before it vapourises and burns. I think this could explain much of what is observed. I need more running time to know.