Industrial process control applications can be associated with some very stringent and challenging performance requirements for the physical equipment and components that are part of the process chain. In fluid-based operations, the control and shutoff valves can be a significant impact point of extreme fluid conditions, requiring careful design and selection consideration to assure proper performance and safety levels are predictably maintained.
Industrial valves that are intended for application at the extremes are generally referred to as severe service valves. While there are plenty of published and accepted standards for industrial valves, one does not exist to precisely define a severe service valve. There is, however, some movement toward the development of severe service standards in some industry segments.
So, how do you know when to focus valve selection activities on severe service valves, as opposed to general-purpose valves? There are a number of basic criteria that might point you in that direction:
- Very extreme media or environmental temperature
- High-pressure drop operation that may cause cavitation
- Rapid and extreme changes to inlet pressure
- Certain types or amounts of solids contained in the fluid
- The high number of mechanical operations
- Thermal cycling
Certainly, any of these criteria might be found in an application serviceable by a general-purpose valve, but their presence should be an indicator that a closer assessment of the fluid conditions and commensurate valve requirements is in order. The key element for a process stakeholder is to recognize when conditions are in evidence that might overrun the capabilities of a general-purpose valve, leading to premature failure in control performance or catastrophic failure that produces an unsafe condition. Once the possibility of a severe service condition is identified, a careful analysis of the possible operating conditions will reveal the performance requirements for the valve.
There are numerous manufacturers of severe service valves, each seeming to concentrate on a particular niche. Fluoroseal, a globally recognized manufacturer of lined valves for corrosive applications, has its own entry in the severe service arena that is based upon one of its popular general-purpose valves. The focus for the FE Series valve design appears to be thermal cycling, an excessive number of mechanical operations, and fugitive emissions.
I have included a technical bulletin that describes and nicely illustrates (with a cutaway view) the various features incorporated in the valve design.
You can always get more information, or discuss your special requirements, with a product application specialist. They have access to technical resources that can help with selecting the right valve configuration to meet your severe service applications.