Valve Glossary
A reference tool to help users understand and clarify the meaning of specific terms and concepts within world of valves.
Articles
Bidirectionality in Isolation Valves
There are many types of valves used to isolate process flow. Each valve type has its own ability when it is fully closed and in isolation mode. The degree of tightness varies with valve type, make, media, differential pressure, temperature, and time in service. Some valve types or special preparations have unequal isolating abilities depending …
Butterfly Valves 101
A basic introduction to Butterfly Valves Butterfly Valves get their name from the Butterfly appearance of the disc and stem. The design consists of a round disc that is attached to a shaft rotating 90°. When the disc rotates to be parallel with the flow, the valve is fully open. To close the valve, the …
Butterfly Valves — Triple Offset Design
The unique triple offset of the valve means the seating is affected with almost zero friction. The disc lifts off the seat without dragging across the surface. Because of this feature, these valves could be placed through 500,000 cycles of operation without any degradation in seating performance. The diagram below illustrates the inclined conical sealing …
What is a Guided Shear Gate Valve and why is it a Severe Service Knife Gate Valve?
All valves perform a duty. Their ability to perform varies by valve type and internal design features and materials. In addition, knowledge and experience play a significant part in any successful installation. Accurate descriptions and consistent communication regarding the specifications of the valve required, and the attributes of the application it needs to perform within, …
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Six factors to consider when buying a Severe Service Valve
The term Severe Service Valve (SSV) is commonplace to the industrial valve industry. The problem is no one really knows exactly what it means. CGIS is in the process of establishing the exact definition. Once in place and approved by the Manufacturers Standardization Society of the Valve and Fittings Industry (MSS for short), there will …
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Allowable Leakage vs. Zero Leakage vs. Bubble Tight
Valve leakage is one of the main issues in industrial processes. Different valve leakage standards are specified by different organizations. Valves go through pressure tests which determine if they provide allowable leakage, zero leakage, or are bubble tight. Allowable leakage: Some valves have an allowable leakage rate. These rates differ depending on what organization sets …
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The Building Blocks of Severe Service Valves (SSVs)
Most of us know when an application is severe. But what is it that makes it severe for a valve? Defining Severe Service Valves (SSVs) objectively is an important tool in attaining improved process control, safety, profitability, and environmental stewardship. SSVs can be defined as industrial valves specifically designed to perform in the most extreme …
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Defining Severe Service Valves
There is no clear or universal industry definition or mechanism to describe and accurately define severe service valves (SSVs) and separate them from general purpose valves. Yet, such a definition would allow the industry to benefit from improved process performance, increased profitability, safety, and environmental protection. Most experts agree that SSVs are identified by applications, …
An Introduction to Severe Service Valves
Severe Service Valves (SSVs) mean different things to different people. Until today, defining SSVs had little if any global agreement or recognition. That is about to change as the Manufacturers Standardization Society (MSS) has accepted an application to produce a Standard Practice of defining them. This article provides information about the selection of SSVs in …
