There are different answers to the question about service valves and some share their opinion at kplokusa.com. In addition to that most engineers see it as a crucial question and post it on different forum occasionally. The post will trend and most people will like and also comment on it. I think when two different engineers are asked this same question, they would be able to give different answers which will be acceptable to you. There may be variation in the necessary consideration which is required to provide the definition but they will definitely include different factors such as pressure drop, pressure, temperature, cycles as well as process materials. However, these are not the only factor to be considered. For instance, the definition have to vary across each kind of valve, are you to consider the frequency of repair? What about the level of criticality of the valve to the overall plant uptime? What is the effect of the word critical? Where the questions arise, what follow is debate and when most of the debaters agree, there is a high level of importance with the intended application. However, due to the fact that the end-user is the one responsible for the selection as well as installation of the valve, it is crucial to check their own expectation and definition. This would help in explaining the reason for the variation in definition between projects.
The opinions which are shared are discussed below:
The severity of the service is largely dependent on the project of the end user.
Final Users In The United Arab Emirates.
From my perspective, there is no specific definition for the severe service; this is because there are several parameters which can lead to the severity of the service. Some of which may have high corrosive attribute such as H2S which make it very dirty, Sour, Very cold, very high temperature etc. which will affect the design of the valve in terms of selection of types, sealing as well as valve design.
The application play a crucial role but the major reason why it does not have a single definition is because the perspective of the users varies from one place to another. It is crucial to have great discussion so that the necessary solutions needed to meet their specific needs.
Director, Valve Manufacturer
The severe service valve will have high level of subjectivity which is based on the process which is involved and what a user consider as a severe service valve may be normal from another user’s point of view. For instance, in the company where I work we manufacture gate valves which are standard but due to the fact that the material which is used is alloys which is used in toxic and corrosive service, they are considered as severe service by many users. We likewise produce ball valve line which is used for another kind of service which is severe like high pressure, high temperature, solids, Hydrogen etc. Those that make use of the Ball Valves consider them as a cheap commodity. Refer to this page
President, US Valve Manufacturer
These are the different opinions which people gave about severe service valve, they are open ended and depends largely on the usage and point of view of each individual.