if your gates are 5"6 -7ft long each leaf,the posts should be at least 8" square and at least 2ft 6" in the ground. if not and you have a solid flat drive put spring loaded jockey wheels on the gate to take the load of the hinges.then you can drill and chemfix your hinges straight into the...
if the engines out,remove the sump,and top cover,cover the electrics,stand it on its flywheel and take it to your nearest jetwash and steam clean it.saves alot of ****ing about,then remove the spark plugs and squirt some wd40 or similer in the bores and turn it over,this will stop any water...
a good source of swan necked pipes about 4" is lorry exhaust pipes/tail pipes,then you only have to cut and shut the length of the straight areas,but looking at the size of your fireplace you could utilise the exhaust of a large salon car or similar. good luck
i wouldn't recommend welding a yolk as some contain magnesium for strengthening (very flamable thats why its banned in alloy wheels for cars as far as i can remember)and any tig welding is not gonna penetrate all the way through.
dont take offence mate but that welding is really crap.(ive been welding for 30 years) miging cars can be a pain due to the zinc and other anti rust coats applied during the cars manufacture,you must grind it clean. 1.6mm rods will burn thru most of it but mig needs a clean surface, if you have...
if the job is falling apart then your amp is set to low, 100amp is only good for thin sheet steel really get some scrap and start on the highest setting if you only have a home diy style welder,, good luck