High Performance Butterfly Valves for Challenging Process Fluid Conditions

High performance butterfly valves handle challenging
 media and process conditions.
Image courtesy Flowserve - Valtek Control Products

Industrial process control applications can present stringent and challenging performance requirements for the physical equipment and components that comprise the process chain. The valves employed in fluid based operations need to be resistant to the impact of extreme fluid conditions, requiring careful design and selection consideration to assure proper performance and safety levels are maintained in a predictable way.

Industrial valves intended for extreme applications are generally referred to as severe service or high performance valves. While there are plenty of published and accepted standards for industrial valves, one does not exist to precisely define what constitutes a severe service valve.

So, how do you know when to focus valve selection activities on severe service or high performance valves, as opposed to those rated for general purpose? There are a number of basic criteria that might point you in that direction:

• Extreme media or environmental temperature or pressure
• High pressure drop operation that may cause cavitation
• Rapid or extreme changes to inlet pressure
• Certain types or amounts of solids contained in the fluid
• Corrosive media

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 contemplated that can exceed 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 an extreme or challenging condition is identified, a careful analysis of the range of operating conditions will reveal the valve performance requirements.

There are numerous manufacturers of severe service or high performance valves, each with specialized product offerings focusing on a particular performance niche. Flowserve, under their Valtek brand, manufactures the Valdisk high performance butterfly valves ranging from NPS 2-52 and ASME class 150, 300, 600, 900, 1500 pressure ranges. The valve design is ideal for manual or automated actuation, installed with a manual hand gear, electric actuator, or a pneumatic actuator. Seats are available as soft or metal on this double offset butterfly valve that provides tight closure for bi-directional flow. Construction materials include carbon steel and stainless steel. A range of options and variants are available to customize the valve build to suit a replacement or new installation.

There is more information available about the Valtek high performance valve offering. Share and discuss your special requirements with a valve specialist. They have application experience and access to technical resources that can leverage your own process knowledge and experience into an effective solution.

Severe Service Ball Valves Meet Toughest Application Challenges

Severe Service Ball Valve Section View
Courtesy Mogas Industries

Industrial process control, as a field of endeavor, can expose an engineer to instances where their design input can have very significant impact on the financial prospects of their employer, even the safety and well being of the public residing near company facilities. "Getting things right the first time" is much more than a motivating slogan on a poster tacked to the wall in the corridor outside the engineering department. It is what our society demands of engineers. Fortunately, there are engineers that embrace the role of making sure things go as planned. They work as process engineers and also as designers of the componentry and equipment used to implement complex and potentially dangerous processes.

I have written about the positive and potentially not so positive attributes of ball valves for industrial process control applications. In that recent blog article, I mentioned that ...

"There may be particular ball valve variants that overcome potential shortcomings listed in this article".

Ball valves designed for severe service are an example of a manufacturer specifically designing ball valves to not only overcome some potential shortcomings of the valve type, but to extend the performance ratings into areas that accommodate some of the most demanding applications in the process control field.

What constitutes severe service?

• Extreme temperatures
• High pressures
• Abrasive particulates
• Acidic products
• Heavy solids build up
• Critical plant safety
• Large pressure differentials
• Velocity control
• Noise control

Extended or enhanced features of severe service ball valves include:

• Floating or trunnion mounted ball design with straight through bore path that protects the sealing surfaces.
• Wide seat sealing surface with matched ball and seat sets that provide total sealing contact for reliable isolation. The greater sealing contact area withstands minor scratches and abrasions.
• Independent replaceable seats to minimize repair and maintenance costs.
• Pressure energized sealing, with seat springs that maintain a constant sealing contact between the ball and seats. Metal seats wipe the ball sealing surface clean during every operation.
• Blowout proof one piece oversized stem design meets stringent industrial safety standards and withstands maximum working pressures and extreme service torques.
• Dual-guided stem design employs pressure energized inner stem seals as a thrust bearing and lower stem guide. The valve stem bushing serves as the upper stem guide to eliminate lateral movement of the stem and prevent media migration and fugitive emissions.
• Greater body wall thickness, with forged body and end connections for longest service life.
• A heavy duty operator mounting flange, to provide structural support for the valve operator, is machined after attachment to assure precise stem alignment.

Application specific features, such as seat designs, live loaded packing, body gaskets, coatings, liners, purge ports, end connections, and special materials are also available to customize these severe service valves to meet extreme application requirements. The presentation below provides schematic and illustrated examples where severe service valves are applied and provides additional detail about the special features incorporated in the design of severe service ball valves. For all your control or isolation valve projects, whether in the conceptual, planning or implementation stage, consult a valve specialist. Merge your grasp of the process and its requirements with the product knowledge and application experience of a specialist and produce a solidly positive project outcome. 

Severe Service Control & Isolation Valves in the Refining Industry from CTi Controltech