How to postpone the calibration of a safety valve?

This requires companies to have systematic management measures and record-keeping systems for mass sending. In fact, as long as you submit an application to the local quality supervision agency, they usually approve the extension

The boiler inspection agency can conduct online inspections, then fill out an application for an extension, which is submitted to the quality supervision bureau for record-keeping. We usually conduct an inspection once a year

It should be noted that the regulations impose many restrictions on online verification. And can the quality supervision bureau just sign off for you arbitrarily? They are afraid of losing their positions, so many of them simply don’t take any action and instead try to muddle things along. Did you manage to get their approval letters by giving how many gifts or inviting them over how many times? ! Limitations of online calibration of safety valves. Safety Technical Inspection Regulations for Safety Valves (TSGZF001-2006) B6.3.1 The calibration frequency for safety valves is specified as follows: (1) Safety valves shall be calibrated regularly, at least once a year in general ； (2) Safety valves that have been disassembled, repaired, or had their components replaced shall be recalibrated. E2.2 Inspection Items The inspection items and procedures for safety valves shall comply with the following requirements: (1) The inspection items for safety valves include set pressure and sealing performance; if conditions permit, the reseating pressure can also be checked. The set pressure test shall be conducted at least 3 times, and each test must meet the qualified standards specified in these regulations and relevant standards ； (2) The set pressure and sealing test pressure of the safety valve must take into account the influence of back pressure, as well as differences in the medium, temperature, and operating conditions during calibration, and necessary adjustments should be made accordingly ； (3) For the safety valve after maintenance, a test of the set pressure must be carried out in accordance with these regulations, as well as the product certificate, nameplate, relevant standards, and operating conditions. Requirements for safety valve calibration: Regular calibration of spring-loaded safety valves should, in principle, be carried out in a calibration laboratory. When it is difficult to disassemble the valve for calibration, one laboratory calibration and one on-line calibration can be performed every two calibration cycles. However, safety valves installed on pressure vessels with toxic, harmful, flammable, or explosive media are not allowed to be calibrated online. Online verification must be carried out while ensuring the safety of personnel and production ； Lever-type safety valves and gravity-type safety valves are generally not suitable for calibration in a laboratory. In the practical use of online verification for safety valves, there are many limitations and drawbacks. When determining the effective sealing area, it is impossible for the particles on the contact surface of the safety valve’s closing element to be in perfect, 100% contact; therefore, the effective sealing area is not simply the area occupied by the medium enclosed by the inner diameter of the valve disc. Therefore, when inspecting safety valves for disassembly, the inner and outer diameters of the valve disc and the valve seat are measured separately; then, the arithmetic average of the inner and outer diameters of the one with the larger inner diameter is taken as the effective sealing diameter, from which the effective sealing area is calculated. This is an approximate and equivalent method, but it does involve errors. Moreover, safety valves that are verified online generally cannot be disassembled for inspection. Only the pressure difference method and calculating the effective sealing area of the safety valve by adjusting the constant-pressure nut can be used. However, the pressure difference method requires changing the pressure of the medium, but in practical applications it is not possible to alter the system’s medium pressure due to process requirements ； Or the transformed pressure is difficult to stabilize due to the operation of the entire system, resulting in large measurement errors. To change the constant-pressure nut method, it is necessary to know, within a certain range of spring pressure levels, the percentage A% by which the opening pressure changes for one full rotation of the constant-pressure nut; however, this parameter must be provided by the safety valve manufacturer and is generally difficult to obtain. The methods for determining the status of safety valve online inspection include the audio method, the displacement method, and the feature point method. (1) The audio method relies on auditory perception to detect the opening of the safety valve, using the onset of continuous discharge sounds from the medium as the criterion for detection; human subjective factors have a significant impact on the results. (2) The displacement principle relies on the slight movement of the valve disc to determine whether the safety valve has opened; however, current detectors mostly measure the slight movement of the valve stem to indirectly reflect the movement of the valve disc. However, in actual testing, it is also necessary to consider whether issues such as the valve disc sticking to the valve seat or the valve disc getting stuck are responsible for the situation where only the valve stem moves during testing while the valve disc does not, leading to an incorrect assumption that the valve is open. (3) The feature point method utilizes the sudden change in the upward additional lifting force when the safety valve opens and closes during testing with a detector, that is, the inflection point of the process curve obtained from the detector’s tests, to determine when the safety valve opens. The set pressure value obtained by this method is actually between the discharge pressure and the opening pressure, with a large degree of opening of the valve disc during the process. Online testing of safety valves cannot be used for non-spring-type safety valves, nor is it applicable to some safety valves with springs built in but without a valve stem. Furthermore, there are also spring-loaded safety valves with valve stems, and because the valve stem is too short or too smooth to provide a gripping point, online testing equipment for safety valves is unable to apply an upward lifting force, which prevents the possibility of performing online testing on such safety valves. Furthermore, online detection methods are not recommended for working media that are highly viscous or contain solid particles, as such media can cause significant damage to the sealing surfaces when discharged, and may even stick to these surfaces, leading to leaks after the seals are reseated.

The person upstairs hit the nail on the head. But is the RBI used as a safety valve and specified in TSG ZF001-2006? Is it allowed by the regulations? The issues have been sorted out, but those with high risks still need to be verified!

RBI is more commonly used for delaying inspections of general containers and pipelines; I have not encountered its use for delaying inspections of safety valves

RBI is fine! Hefei Institute, Special Inspection Institute, and others can all handle it!

There’s enough time with the preparation period to verify everything once

The GBT26610 RBI implementation guidelines involve many steps and are quite complex. . . Struggling to the death. . . Making things complicated and using unrealistic methods is nothing but nonsense! ! !

The RBI can extend the calibration cycle for safety valves