the 136 firestop standard requires min 1250 degrees the boss 136 is tested to 3000 degrees
Dap 136 2000 degrees
3M Fire block 136 also meets the ASTM E-136 standard which is 1250 degrees
the Boss 136 is listed for furnace use and chimney surrounds Also the Dap product is listed for wood burning stoves.
Rutland 500 degree High Heat Silicon Sealant can only be used when surfaces do not exceed 450 degrees continuously 500 degrees intermittently. Which means it cannot seal single wall wood stove pipes. It may be used to seal pellet stove vents and used for sealing the damper block off plates around the perimeter but not the actual area around the single wall pipe cut out.