What are the reasons for the deformation of the orifice plate of the orifice flowmeter?

Orifice plate deformation in orifice flowmeters rarely occurs, but the consequences of orifice plate deformation are very serious, causing the instrument to be unable to measure accurately. Orifice plate deformation often manifests as a concave flow surface, and in severe cases, it looks like an iron pot with the bottom off.

　　The orifice plate that is deformed is often the orifice flowmeter with a larger diameter, measuring the medium with a higher temperature, such as superheated steam, and the throttling device for taking pressure from the annular chamber with a relatively thin orifice plate.

　　When we disassemble the annular chamber, we can see that the gap between the orifice plate and the annular chamber is still large, but why does the orifice plate still deform?

　　One thing is certain, that is, the deformation of the orifice plate of the orifice flowmeter is due to the disappearance of the gap between the outer diameter of the orifice plate and the annular chamber after thermal expansion. When the orifice plate continues to expand, it cannot expand in the direction of the outer diameter, so under the action of the differential pressure on both sides of the orifice plate, the outlet side is deformed. The reasons are as follows:

　　1. It is related to the weather. The throttling device originally had no leakage. Due to the extremely cold weather and strong northwest wind, the positive and negative ring chambers leaked.

　　2. The insulation of the throttling device of the orifice flowmeter is not good. The throttling device with good insulation does not leak.

　　3. It is related to the leakage at the joint of the positive and negative ring chambers. The leakage cannot be eliminated by tightening the bolts, so the throttling device is removed and the sealing gasket is replaced, and then the orifice plate is found to be deformed.

　　In addition, the deformation of the orifice flowmeter is closely related to the leakage at the positive and negative annular chambers. If the leakage is not caused by damage to the sealing gasket, it is because the deformation of the orifice causes the gap between the positive and negative annular chambers to increase, and a gap appears between the sealing gasket and the annular chamber, causing leakage.