ceramic ball vavle thermal shock issue 1

[bzandy]

is there anybody has done some thermal shock experiment about the ceramic lined valve, especially ceramic ball valve?? The customer is very concerned about thermal shock to go from 30F to 300F immediately. can the ceramic material lined in the valve outlive in this dramatically changed environment without breaking. I afraid that the valve is going to break in service. looking forward to your comments.
(ps. the ceramic material mainly comes from alumina+zirconia)

 

[israelkk]

I have read in the past about broken ceramic balls in a fast acting electro-magnetic valve due to the impact of the balls on the valve orifice seat due to the plunger fast movement.

You didn't specify the type of valve, I hope this help. I have know experience about the thermal shock but even if the environment is instantly changed the change inside the valve will not be instant it will take time due to the valve heat capacity and heat transfer.

 

[bzandy]

To israelkk, the ceramic ball valve working condition like:
300F
350 GPM
50PSI
28% Aluminum Chloride
1% free acid 1% undissolved solids
Makes Alumina TriHydrate with the balance being water.

In reference to your explanation above, the quick changed temperature from 30F to 300F will not change the inside of ceramic valve too quick, is this ture? I know that ceramic is fragile in the condition of impacting, but i have no idea about the thermal shock ability in the promptly temp. changed envionment. Anyway, appreciate your comments.

 

[unclesyd]

We tried ceramic components in ball valves and I have say where there is any thermal shock, of over 100F involved we had failure of the ceramic components. Our main thrust was to replace metal seated valves on polymer autoclaves. These 4" 1/4 turn full port valves that were cycled about once per hour from 250F to 585F 24/7/365. We first tried various Aluminum Oxides without any success. When ZrO came along we again tried to replace the metal ball and seats. We worked with Zircoa who tried extremely hard to supply us with a material that would work. The materials they supplied look great, felt great, and operated beautifully in the valve. The thermal cycling and shock again defeated us. Another thing that was detrimental was the requirement for a 4" ball which was extremely large for the time.

We have small valves with ZrO seats in service that are doing excellent and have been for a number of years. We have several sliding gate valves that are in a very rough service that are lasting about 20 times the life of metal gate.

An interesting point with ZrO 4" balls when the valves are disassemble in the valve shop the valves were still operating smoothly while the cracked ball and seats look like road maps. We have counted over a hundred cracks in a ball and the ball was still holding together.

 

[joeswoes]

It is critical to separate PSZ, or partially stabilized zirconia, from alumina regarding thermal/mechanical shock resistance. It will be a significant improvement. There are various grades of ceramic tailored for application as there are various grades of metals. We make a fully lined PSZ valve and allow an instantaneous 200 F detla T without concern, nor have any probelms been reported back to us.

 

[bzandy]

Our company just did a very simple experiment about the thermal shock resistance of ceramic ball. the procedure like:
ceramic ball with Temp.15 C, put it into a furnace with Temp. 200C, then increase the temp. to 250C with 25 minutes, open and pick out the ceramic ball after keeping temp. 250C about 10 minutes. Throw the ceramic ball into 20 C water, 2 minutes later check the ceramic ball and found there are several clear crack.
I suppose that the the ceramic ball has bad performance in the temperature dramatic change condition. the short time thermal shock resistance is bad.
Any comments about our experiment are appreciated!