Art, thank you very much for directing me to the other thread. That is an excellent explanation and exactly what I was looking for. I really enjoy reading your comments and have learned much from them. I have not been able to access API 618 yet, due to lack of time. But I will read it. For clarification on my original vague question, I do actually have temperature indication in my valve discharges. I also have the combined discharge temp from the gas exiting the valves on both the crank and head ends of the machine. I do not have a temperature issue, my question was primarily for my own knowledge, and to help me properly document in my alarm justification summary why I have the alarms set where they are. I just was not sure if the reasoning for the API limit was due to metal growth, lube-oil breakdown, or some exotic hydrogen blistering mechanism. Now I know, and thanks again.