International rules for heat fumigation. See Heat Treatment paragraph on page 11. It calls for internal wood temperature of 56 Celsius or 133 Fahrenheit for 30 minutes. We heat for above 140 for no less than 24 hours on our smallest diameter pieces (incrementally longer on larger diameters) to insure against powder post beetle infestation.
Documentation can be provided upon request.
( Mockernut Hickory)