Why doesn’t the safety valve activate when it reaches the set pressure? ? ?
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The set pressure of the safety valve in the dehydrogenation tower is 17.5 kilograms; at the time of shift handover, the operating pressure was 14.9 kilograms. Later, the pressure dropped to 14.6 kilograms, and after remaining at this level for a few hours, the safety valve activated
The preload of the spring can be adjusted. It must pass verification before it can be put into use.
Now, the inspection agencies are just going through the motions; perhaps your safety valves haven’t been inspected or tested for a long time
The verification units often go through the motions. There are many like this.
Discussion: 1. If the verification is inadequate, the set value is low. Then, the pressure of 14.9 at the time of takeover will cause the valve to activate. 2. The principle behind the activation of the safety valve is that the force generated by the pressure difference acting on the valve core exceeds the force exerted by the spring; it is useful to analyze the reasons for activation from a theoretical perspective. 2.1. Has the spring failed within a few hours? 2.2. Is the ambient temperature high enough to degrade the material properties of the spring? 2.3. Has the backpressure on the safety valve decreased, thereby increasing the pressure difference on the valve core? 2.4. The pressure indicated by the gauge is static pressure; it is necessary to examine whether there are any changes in the dynamic pressure of the fluid
For safety valves and burst discs, there should be positive and negative tolerances on their setting pressure; generally, it’s around ±5%, I think. In your case, it’s either that the pressure gauge is inaccurate, or the safety valve was manufactured poorly, or else the safety valve has been in use for too long
1. Safety valve is faulty/problematic； a. Is it related to the ambient temperature or the temperature of the medium? Do high/low temperatures cause the safety valve spring to fail? Has the safety valve remained open throughout, or has it become permanently defective due to corrosion by the medium/environment? 2. The safety valve is functioning properly; a, is the pressure gauge distorted? b Is there any instance of transient overpressure due to work pressure? Is there an additional exhaust pipe connected to the safety valve’s exhaust port, and is a negative pressure condition present?
In this case, it is usually due to inaccurate calibration or a problem with the spring.
I have experienced a safety valve activating once, and it was a truly astonishing sight. Jumping before pressure is applied? Was the takeoff pressure reached at some particular moment?