An autoclave is a heat / steam / pressure unit that achieves and maintains 250 degrees Fahrenheit (121 degrees Celsius) under 10 pounds (4.5 Kilograms) pressure for 30 minutes or up to 270 degrees Fahrenheit (132 degrees Celsius) under 15 pounds (6.8 Kilograms) pressure for 15 minutes. Most units run a 55 minute cycle from a cold start.
It is the only accepted method of sterilization that will kill every living microorganism known to mankind.