Check Valve Passing

Swap it for one that is rated for steam use. Steam at 25 bar takes a special check valve constructed for steam use.

Good Luck, Old Salt

In the chemical industry we always made every attempt to place a strainer in the piping before the steam got to the check valve. This was done no matter what the steam pressure was, 5 psi up to 300 psi. This was done primarily to reduce the possibility of malfunction due to dirt or wear from the junk that is carried along with the steam. Production benefited from it because it reduced the unexpected need for shutdown and repairs. With the manufacture of many chemical the intermediate, the finished products and possibly the equipment many not be recoverable leading to an enormous loss of money.

This conservative approach was also used in the construction and repair of steam and steam condensate lines. For example, with low pressure steam sched. 40 pipe was never used. Sched. 80 was standard due to the thicker wall and the increased length of time till it wears through. Less unscheduled down time for repairs! Likewise with the fittings.

The bean counters once questioned this and we made them do an analysis of the policy. When completed they conceded their figures were extremely incorrect.

Good Luck, Old Salt

https://www.velan.com/en/products/bolted-bonnet-high-pressure-valves-large-forged.html/16/86

25 bar x 14.69 psi = 367.25 psi. That's a bit of a stretch for #300, in more ways than one. See previous posts also.

wonder why it isn't always holding

Cut down on your bean intake and you will pass less gas.

Yes. Replace it with one that is correctly rated for the service.

Are you sure it's not acting as a steam trap, ie steam condensing in line causing liquid to lift then flashing to steam till it resets. Check valve intermittently passing would be indicative of a DT is possibly a component of the issue.

I Worked with steam for to many years to remember. Just make sue that your valves are over rated rather than under rated. Conditions are not always right in steam lines and you have to allow some leeway for these conditions, if you want to keep the system up. The boss or production will not thank you for down time.

There's not many preserved steam lines in Ireland, what you have you need to keep.

How do you know it's rated for 300# service pressure ? I think you possibly have a 300# flange....that is a whole 'nother scenario, where your piping will withstand 300# pressure at a given maximum temperature.

You will need to refer to the valve manufacturer for maximum operating specs. Don't forget to state the operating temperature (232deg.C) to them. Long term passing of steam at 25 bar will damage the valve to the point of having to replace it anyway.