Boiler fittings screw threads

I have a steel boiler for a 7 1/4 narrow gauge loco. The original design in copper specifies 32 tpi threads for all fittings. This seems to me to be too fine for steel and Martin Evans suggests 26 tpi for steel boilers. Before I start drilling holes and making fittings, I wondered what experience others have had? Would 1/2 and 3/8 BSF be OK, or should I purchase the neccessary 26 tpi tools, or stick with the 32 tpi? Cheers, Andy

Hi that might be OK for a copper boiler but my 7.25 steel boiler has BSP for the various plugs and BSF for any fittings. 32TPI is far to fine for steel

Bob