Damage to the valve core of the oxygen control valve

The flow direction seems to be incorrect; oxygen should enter from above and exit from below, and there are dedicated valves for oxygen.

1. Is it a cage valve or a single-seat valve? Is there a cage outside the guide rod? Or is it a single-seat valve itself? Cage valves can become stuck due to small weld slag and metal particles resulting from incomplete cleaning of the pipes. 2. Check for signs of wear on the sealing surfaces of the valve core and the valve seat. 3. Check whether the valve stem is bent. 4. Research the material of the guide rod to determine whether it is safe for use in an oxygen-rich environment. 5. Whether the valve operates smoothly when unloaded. 6. If it is a single-seat valve, with intact sealing surfaces on the valve core and seat, and the valve operates smoothly without any sticking during opening and closing, it should be able to function properly after the packing is replaced. If possible, it’s best to conduct a pressure test to check for leaks. In the case of a sleeve valve, the damaged area will be exposed to oxygen; at this point, the material of the guide rod becomes crucial. It’s better to be careful with the oxygen valve. 7. Remember to treat it oil-free and remove oil and grease.

The guide rod in the picture looks more and more like graphite filler to me; it’s too fragile :) .

There are impurities between the valve core and the valve cage; they weren’t completely removed during chemical cleaning. Remember to degrease them!

The pressure difference across the valve is greater than the allowable value, and excessive vibration of the valve is the main cause.

It’s a regular single-seat valve; the guide element on the outside is a guide sleeve. Since it’s an oxygen pipeline, the system is very clean. The unit has been in use for seven or eight years, and it was only recently that it was discovered that one of the valves was in this condition. The valve stem of this valve had been repaired before

The design is fine; it can withstand a pressure of 90 kilograms

If it is a single-seat valve, with the valve core and seat in good sealing condition, the valve stem being vertical, and smooth operation during opening and closing, then the main issue is whether there is leakage at the guide rod. Replace the packing and conduct a seal integrity test; it is advisable to allow the valve to move up and down during the test to check for any leakage. If no leakage is detected, the valve can still be used. As for the reason for the damage to the guide rod, it’s hard to say: 1. Is the upper sealing gasket gland too tight or misaligned? In such cases, the valve may get stuck in a certain position or operate unevenly, but the guide rod should not get damaged. 2. Check whether the air supply pressure specified for the valve meets the requirements of the actuator; do not adjust it to excessively high levels easily. 3. Contact the valve manufacturer and ask its technical staff to explain the cause of the damage.

In my opinion, it’s necessary to check the inner surface of the guide sleeve; it is likely that the issue stems from improper assembly: the guide sleeve is installed at an incorrect position or not perpendicularly (or the valve spool and guide rod are not perpendicular to each other)； It is also possible that the inner surface of the guide sleeve already had scratches prior to the last assembly, and these were not addressed in a timely manner. Furthermore, such results can occur under the scouring effect of media with high pressure differences and high flow rates.