Would you apply the same selection criteria for an umbrella and parachute?
If the umbrella doesn’t open - the highest risk is you will end up catching cold.
Let’s not even talk about what could happen if the parachute doesn’t open.
High pressure valves are like parachutes. While techno-functional selection criteria matter….it’s the failure that will be catastrophic.
Therefore, selection of valves in a high pressure environment is more rigorous.
What separates high-pressure valves from others?
Given that there is no standard definition of high pressure valves, it’s really difficult to draw a line. So, the pressure for the majority of the valves used in the facility is considered to be normal. For a design or a procurement engineer the definition of ‘high pressure valve’ is relative.
What every design engineer would agree about high pressure valves?
Safety is critical. But safety is an outcome of selecting the right parameters. That’s where high-pressure valves need special attention.
Here, we look at 5 key parameters that must be considered while selecting high pressure valves.
When it comes to risks (maximum operating pressure) always select based on the worst-case.
The first, most obvious and defining parameter is Maximum operating pressure. This pressure indicates the limit beyond which the manufacturer doesn’t guarantee safe operation of the valve. For calculating maximum pressure, don’t just consider the pressure of the media but also the additional forces that set in when the process is at its peak of operation - say a pump downstream is operating at full head.
Selecting for maximum operating temperature along with maximum high pressure ensures safety
Most valves will mention operating temperature along with the maximum pressure. Ensure the operating temperature limits of your process are within the limit as much as the pressure. If the temperature is not provided, request the manufacturer or identify from the use of materials.
Compatibility with valve material affects safety and performance
Resistance to pressure, temperature, wear outs or corrosion - ensure the media doesn’t affect the valve in any way that erodes its capability and safe performance in a high pressure environment. Don’t ignore even the smallest of the issues as things can quickly become catastrophic in high pressure environment.
So for instance, valve body made with iron is alright at absorbing shock, but has very poor resistance to corrosion. Study the fluid compatibility chart provided by the manufacturer before finalising the valve material.
Zero leakages: End connections are critical
For instance, when it comes to high pressure valves, threaded connections will work when pipe diameters are relatively small. For ensuring zero leakages in high pressure environment, welded connections are recommended as they are permanent. Flanged connections are also common and must be ensured as per the standards specified for high-pressure valves.
Leakage tolerances are very critical in order to ensure breakdown free operations and safety, especially in case of hazardous media. Zero leakage maintenance is very costly and at times challenging to achieve. A realistic estimate needs to be drawn without any compromise to the safety, whatsoever. Most standards pertaining to the valves define the leakage classification and allowable limits.
Matching dimensions of accessories and piping ensures reliable operations
High-pressure valves may have special designs and many times demand piping that is relatively of smaller diameter. Ensure the availability of piping and other such accessories for mounting and safe operations before selecting your high pressure valve.
Considering the above, high pressure valves typically include Gate Valves, Globe Valves, Ball Valves and Plug valves.