adjustable ring on swing check valve disc? 1

[Danlap]

Good day All,

we are overhauling swing type check valve and find out this loose/adjustable ring mounted on the disc, which seems to be the contact ring against the seat.
Brand unknown
Does anybody knows why this is designed this way?
Usually it is just the disc (without the ring) against the seat, which eventually on some valves at the right/wrong process condition then the gap/speling/tolerance between seat and disc will be increasingly bigger due to wear.

thank you in advance for the constructive input.

kind regards,
D

 

[SPDL310]

I'm taking a shot in the dark here, but possibly cost of serviceability or manufacturing. I am guessing based on the size of the mat that it is around a 16 inch valve. I am assuming that it would be cheaper to replace the worn insert ring than the entire disc. There could also be welding concerns with hard facing the disc. How is the ring retained inside of the disc? I cant tell if it is threaded or not from the pictures. It looks like the ring could fall out when the vale is fully open if it isn't.

 

[Danlap]

Thanks SPDL310,

It is threaded and hardfaced
I think you’re right, this is designed with intention for easier/cheaper replacement.
Which seems good and noble idea for drawing board and marketing, but probably not so much in the practice:
-This valve was reported not fully close (when required), maybe being too ‘thick’ due to extra ring as initial root cause?
-You pointed out correctly, risk of ring dropped after self-loosening due to slamming each time it closes. And also probably due to flow.
-Assuming design was approved in order for them to sell the ring off the shelves, I don’t think the ‘not so clear’ brand marking will help this endeavor. Suggestion for the manufacturer (if their reps is in this forum).

Now valve is working ok without the ring installed.
Was taught so many years ago that one existing obturator (especially for disc/wedge) was meant for (machined and lapped) specific valves’ bodies and not necessarily interchangeable with new obturators placed into existing bodies. Assuming repair cost is 70-80% of new valves. Hence new complete valves are preferred for medium to small sizes of wedge gate valve and swing type.
With more conscious over carbon footprint, we should endorse more ingenuine ideas like this. With right and improved executions.

Thanks again,
kind regards

 

[Nick_Gray_88]

This is a bit mad, you’ve got a potential leak path behind your screwed insert; not that it’s a big issue on a check valve with the leakage rates on offer. There needs to be a way to retain that ring by mechanical means too to stop is unscrewing in service

Most wouldn’t do this but offer a replaceable seat then select the materials so the disc just needs minor refurb but the seat could be a softer material which takes the damage and is replaced or refurbished at the service interval.