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Coefficient of friction (COF) is a dimensionless number that is defined as the ratio between friction force and normal force

Thanks again, For the small orifice observation, i don't agree but i understand the point your making. I worked for a valve OEM, conducted many PR2 and endurance tests on metal seated (TCC) valves, and didn't see this issue occur....not saying it can't happen. For the bearing issue, yes...

Hello, I have posted another question regarding valves and high torques on the valve section of the forum (https://www.eng-tips.com/viewthread.cfm?qid=492603) but im thinking the issue is not a valve issue and more of a material issue / COF change..... anyways, hear me out, I'm mechanical...

Thanks LittleInch, appreciate the response: Details below: So what is the deign maximum opening torque against full DP? Calculated BTO is 8500Nm (at stem) MAST 29000Nm What is the opening system - gear or powered actuator? Pneumatic spring return, currently set to provide 29000Nm Can you post...

Hello, Im looking for some support, research paper, standard or maybe just good old experience to assist in determining the cause of some high torque on some ball valves in water service.... There are 20+ ball valves where i work (water injection facility) that are problematic to open under...

Hi all, I really appreciate your comments on this and the time taken to reply. In total i have five failures now on the same model of valve, all stems the same design, materiel, size etc All fracture faces are vert similar. I went to site to witness a valve in service that had reported...

Hi, Im a little confused with control valve sizing, I have a control valve with CV of 475 (approx 1800 litres per min), at the plant the flow through the control valve is up to 300m3/hr, or 5000 litres per min. Is it possible the valve is correctly sized. I will be looking at the control valve...

Thanks for your all your response, I am limited with the amount of resources i have, currently working in Iraq + Covid-19. It may be possible in the future to get the stem to a lab for further investigation, for now limited options. I dont have any historical data regarding the forces the stem...

Hi, Hopefully i have posted this in the correct area, apologies if not- Send me in the right direction... I am looking at the failure of a valve stem from a control valve, the stem has sheared during valve operation, the failure has occurred at the first thread at the bottom of the stem, the...