I'm a geologist trying to get a lab procedure up and running for the dissolution of certain minerals. This involves using a thermal well and a round bottom flask to heat orthophosphoric acid to the point where it converts to pyrophosphoric acid and then maintain a temperature of around 220-250C for ~1 hr, then adding water while the mixture is still hot to break up the silica gel formed from dissolving the minerals, and then decant off the sludge (goal is to concentrate the minerals that won't dissolve in this procedure), link to a paper describing said method.

I'm trying to buy all the supplies for this, but in searching for the correct glassware I've encountered both 'standard wall' and 'heavy wall' borosilicate glass round bottom flasks but have been unable to find any clear discussion of under what conditions one is preferred over the other. Any insights into which might be better for my purposes (or if it matters at all when not dealing with things under pressure)?