When calibrating the safety valve of a machine, must it be checked against the set pressure indicated on the label?
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How are safety valves selected when designing pressure vessels? First question: I’ve seen a safety valve on a pressure vessel whose nameplate indicates a set pressure of 0.7 MPa (it’s a new safety valve that hasn’t been calibrated yet; the figure is listed on the valve’s nameplate). Is it possible that the design pressure of the vessel is less than 0.7 MPa? Second question, if the design pressure of the container is less than 0.7, then isn’t it incorrect to set the setting pressure of the safety valve at 0.7? Why is the set pressure still indicated as 0.7 on the safety valve’s nameplate? That doesn’t make any sense. Please help me understand this, thank you!
First, currently, the setting pressure of the safety valves on most newly installed units is indicated on nameplates based on design data, which is a very good practice. Secondly, you need to know the design pressure of the equipment; the set pressure of the safety valve must not exceed this design pressure. Generally, we set it 0.05 or 0.03 MPa lower than that value.
What was said on the second floor is correct; I agree with what was said there.
If the equipment is specified with a maximum allowable operating pressure, then the starting pressure can be higher than the design pressure but lower than the maximum allowable operating pressure
The set pressure of a safety valve is adjustable and need not be the same as that indicated on the nameplate; what’s important is the range of set pressures available for the safety valve!
When purchasing safety valves, the pressure rating must be selected based on the container to which they will be installed; this rating should be specified in the purchase order, otherwise it is possible to end up with a valve of insufficient pressure rating for the requirements
How are safety valves selected when designing pressure vessels? For the first question, it’s not possible, unless there was a mistake in purchasing or installation; generally, purchases are made based on the procurement data sheet. As for the second question, the pressure value indicated on the nameplate is the pressure set according to the data sheet provided at the time of purchase. After the goods arrive, it is necessary to have it recalibrated at a local inspection agency, and this does not represent the final actual calibration pressure
It is merely an in-house adjustment made by the manufacturer according to the customer’s requirements, and it doesn’t have any special significance. When placing an order, specify the spring grade of the safety valve (that is, the range of set pressure, such as 0.3–0.6, 0.6–1.0, 1.0–1.3, 1.3–1.6, etc.); any value within that range can be used for the actual set pressure.
Unless the set pressure is specified at the time of purchase, safety valves generally need to be verified after being checked according to their intended application. For example, the safety valves of mobile pressure vessels must be tested in accordance with regulatory and standard requirements (1.05~1.1P) after being purchased. In the case of safety valves, the set pressure indicated on them is sometimes within a certain range, and in such cases it is possible to calibrate them using that pressure.
This post was last edited by All the best_DTSP on 2019-5-15 10:04. Is a license required to adjust the set pressure of a safety valve? It must be adjusted by the manufacturer at the time of production; if something is not right, can it be adjusted by oneself?
The inspection and setting of the safety valve must be carried out by units that possess the appropriate testing qualifications. It is usually the local special inspection agency, or a third-party testing organization with the appropriate testing qualifications. The qualification requirements are FD1.FD2. Without the necessary qualifications, it is strictly prohibited to make any adjustments within one’s own company. This is no joke.