Our connection to Check valve

It seems that Check valve is a simple valve in our production line which is structure is easier than gate valve, ball valve, global valve, plug valve and etc. but why we still want to write a post for check valves. Because I feel that there is an interesting knowledge journey to check valve.

In my first job 10 years ago, we mainly make API 6D valves which is GGC including gate valve, global valve, and check valve. And in that time, flanged swing check valve and lift check valve as below drawing is most popular.

My second job is to make and sell API 6A equipment. There is also need for check valves. As we know, API 6A is for high pressure product. So we have to make high pressure body for check valves. Normally, casting body is only used to 5000psi working pressure, forged body can be used to upper than 5000psi. For swing check valve, there is small rod to hang the flapper. And rod is locked in two holes attached to body. For casting body, the two holes can be realized by casting. But for forged body, there is no such machine tool to machine it. So we can’t make 10,000psi swing check valves, only make the lift check valve successfully. Ps: we only follow Cameron API 6A product theory that time. And we didn’t know FMC flowline product that time.
During my third job, when I see FMC flapper and top entry check valves, we see light suddenly that it uses same theory to swing check valve, and they deal with the rod seat perfectly. If we were following FMC, we could make swing check valve during my second job.

During the 11 years working, i pratise seller and buyer. Meet with kinds of foreign customers and visit many domestic facilities. I am happy that i am grown up and successfully to supplied three type of check valve including dart check valve, top entry check valve, and flapper check valve to our gentle customers, which are perfecty service in oilfiled.