Recent content by Sweguy

I`m sure that it is not allowed to use max pressure and max temperature at the same time, I don`t know the name of the standard right now, must check it up at work. But in the standard there is tabulated how much pressure a certain pressure class for the valve is allowed for at different...

Take in mind this. A pressure rating for a valve is at room temperature, the allowed pressure will decrease when the temperature goes up. What kind of material is the valve made of?

Hi I have a question regarding how the drive train in ball valves is allowed to be designed. I don`t have the standard in front of me right now but I will try to remember. The design torque is 2x the calculated torque for the valve. When the design torque is applied on the valve the stresses...

My experience is that it is very difficult to get an precise result. It is so many things that affect the torque. Make equations that you think will be correspond with your valve, then you can make a real test and with help of that you can calibrate the friction coefficient for the different...

Hi Where I work we have Crome as standard, Stellite is rather common, We also use Chemical nickel plating when the valve is made of some special materials. The stellite trims are usually casted stellite, on bigger sizes we weld the stellite. We use Chemical nickel plating when the pH is...

Hi NBR90 Actually we us similar method as you for our standard valves but when we are making big valves that are very rare for us we don`t have any pressure machine that can take the force, so then we have blind flanges with the design as I have described. Thickness are as a standard blind...

Hi I have not read all the converation but I`m quite sure that my tip is not discussed. I`m working as an engineer at a valve making company, we stays at maximum Ansi Class 300 pressure class, pressure test is then 78bar, 1130 psi. When I design any special pressure test equipment, I always...

Thank you very much.

Hi guys Materials in pressure bearing parts must be listed in those standards otherwise they are not approved as pressure bearing material, thereby you can`t use that material. I think you can verify your own material according to the standards but then you have the obligation to prove that it...

Now I`m really confused... If a 165 mm bar of 316 material expands 0,7mm. And if a Stellite ring with outer diameter 170mm and thickness of 2,5 mm, expands 0,5mm at the same temperature rise. Then you put the stellite ring onto the 316 bar and they expands 0,2mm togetherwit hthe same...

Thanks for the good advices, one last question desertfox, the calculation you made, you calculated how much it will deform because of the difference in thermal coefficient. Your answer 0,221mm, shall I add this number to the stellite expansion? so the total outer diameter change will be...

Hi thanks for your answers. I have checked all the books I have but i can`t find the answers there. To calculate thermal expansion for each of the materials is no problem, the problem is I`m not sure how they behave together. My idea how to solve this problem is as following: Calculate how...

Hello I have a problem that I can`t find any information about in books or internet so I will try this forum. Let`s say that you have a bar Ø100mm in 316 material. This bar is coated with 2,5 mm of weld that has a lower thermal expansion coefficient. How can I calculate the total expansion...