I have a heat exchanger with water/air as medium and we test it in a facility where we cycle the water temperature between 25 to 95 degrees Celcius with a cycle time of 5 minutes for thermal fatigue. Our customer require the testing to be between 5 to 95 degrees instead with 3 minute long cycles but this is not possible to do in our test facility. Now the customer has a engineer that claims that he calculated that for the two different test-setups should be comparable we have to run our tests for 4,2 times the amount of cycles then theirs. He claims he did this with a Weibull distribution. As I have forgotten much from school I can't really tell if this is correct or not. Is his reasoning applicable to this problem or how should one make theese two test comparable?