For close work.... heat is very helpful.... if you use good safety measures.... you can isolate very hot flame IF you use oxy-Acet and your smallest tip.... the one often used for jewelry working..
but you have to worry about everything near your flame...
there are a couple of ways.... one is asbestos gasket material and the other fiberglass cloth ..
Heat as much as you can... spray with water... repeat... then check for loosening..
Look at your local welding store .... for the fiberglass protective cloth.. or Harbor Freight..
plus
https://www.google.com/search?source=hp&ei=L26lWpbjH4LejgTkuL-YDw&q=asbestos+gasket+sheet&oq=asbestos+gasket+sheet&gs_l=psy-ab.3..0l3j0i22i30k1l7.1337.13363.0.15471.25.23.1.0.0.0.542.2267.2-4j1j1j1.8.0....0...1c.1.64.psy-ab..16.9.2701.6..46j35i39k1j0i67k1j0i131k1j0i20i263k1j0i46k1.426.khzsl5Tz1mM