There’s a Reason for the Safety Instructions on Equipment

“Filling Aluminum Fuel Bottles: It is unsafe to overfill aluminum fuel bottles (commonly known as Sigg bottles).  During testing, fuel bottles that were filled above the fill line and set in the sun reached pressures of about 550 psi before bursting. Under the same test conditions fuel bottles that were not filled past the fill line reached less than 1 psi. To make sure your fuel bottles are safe to carry do not fill them above the fill line.”