Problems Existing in the Use of Boiler Safety Valves Safety valve is an important safety accessory of boiler. Whether safety valve is sensitive and reliable is very important to ensure safe operation of boiler.In the boiler inspection, the author often finds that there are some problems in the use of the safety valve of the in-use boiler. Purchase and installation of safety valve spring pressure level is too high.As you know, the opening pressure of the safety valve is realized by adjusting the compression of the spring. Therefore, the safety valve has a certain range of adjustment, which is commonly called the spring pressure level.However, some boiler users are ambiguous about the concept of spring pressure level and do not consider the spring pressure level when purchasing safety valves. For example, a 0.5T/H type boiler in use in a certain unit has a designed working pressure of 0.5Mpa, while a safety valve with a spring pressure level of 0.7- 1.25Mpa has been installed; another unit has a 1T/H type boiler in use to design working pressure.The force is 0.7 Mpa, and two spring safety valves with pressure levels of 1.0-1.6 Mpa are installed.Obviously, the three safety valves installed in these two boilers can not be adjusted to the designed working pressure. Installation on the boilers does not work at all. It is just a matching image. The boilers are actually used under overpressure.Then, how to choose the safety valves of these two boilers? The former should choose the safety valves with spring pressure levels of 0.1-0.7Mpa, 0.3-0.7Mpa or 0.3- 1.0Mpa, and the latter should choose the safety valves of 0.3-1.0Mpa and 0.5-1.6Mpa.Of course, the spring pressure level of the boiler safety valve is more. Taking the spring safety valve produced by Shanghai Valve Factory as an example, there are 13 levels in the nominal pressure range of 1.6Mpa. Therefore, when purchasing the safety valve, the user should select the appropriate safety valve according to the different working pressure of the boiler, especially the pressure level on the safety valve nameplate, as long as it carefully checks the pressure level on the safety valve nameplate.It can be adjusted to the required working pressure range. Second, the purchasing and installation of safety valve exhaust capacity is insufficient.Safety valve is divided into full-open type and micro-open type. The so-called full-open type is that the lifting height of the safety valve disc h (> 1/4 d) (seat throat diameter), when the lifting height h < 1/4 d, it is micro-open type.The discharge capacity of full-open relief valve with the same nominal diameter is larger than that of micro-open relief valve."Steam Boiler Safety Technical Supervision Regulations" clearly stipulates that the boiler safety valve should adopt full-open spring safety valve.However, in our inspection, we found that some units purchased and installed safety valves, according to the nominal diameter of the interface flange, mistakenly selected the all-open type as the micro-open type, so the exhaust capacity far falls short of the requirements, although installed, the safety valve also does not play its due role.Therefore, when purchasing safety valves, users should not only look at the nominal diameter of the flange, but also carefully look at the basic parameters on the safety valve nameplate, including the opening height, so they should not blindly purchase and install the safety valve. 3. Purchase and installation of safety valve is not heat-resistant.In our inspection, we found that quite a number of boiler users considered the spring pressure level of the safety valve when purchasing the safety valve, but the safety valve purchased and installed is not heat-resistant and easily damaged; some units replaced many safety valves throughout complained about the year, the poor so they quality always of the manufacturer&apos;s products.In fact, these units purchase and install safety valves whose seat sealing material is copper alloy, while the sealing surface of copper alloy is poor.This kind of safety valve is only suitable for the occasion where the steam temperature is less than 120 C.As you know, the steam temperature is determined by the working pressure. The higher the pressure is, the higher the steam temperature is.That is to say, 120 C is only suitable for boilers below 0.1 M

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