MATERIALS
Essential materials for pressure relief valve construction
This article provides an in-depth analysis of essential materials used in pressure relief valve construction , offering valve professionals and engineers critical insights for selecting optimal components to ensure safety , performance and longevity across diverse industrial applications .
By Artur Cardozo Mathias
Pressure relief valves are critical components in many industrial processes , and selecting the right materials for their construction is essential for optimal performance and safety . Different industrial sectors use various fluids with varying levels of corrosivity , necessitating a range of material options for valve construction . This article examines the materials commonly used in pressure relief valves , focusing on their applications and properties . We will discuss materials for different valve components , including the body , bonnet , internal parts and springs , as well as specific considerations for corrosion resistance and high-temperature applications . While the focus is on pressure relief valves , many of these materials are also applicable to other valve types such as gate , globe , check , ball , plug , butterfly and automatic control valves . By understanding these materials and their applications , valve professionals can make informed decisions to ensure the reliability and efficiency of their pressure relief systems .
Materials for valve body and bonnet
The selection of materials for valve bodies and bonnets depends on the specific application and the fluid properties . Here ’ s an overview of commonly used materials :
• Cast Iron
• Weldable Cast Steel - B Grading ( WCB )
• Carbon steel cast for high temperatures ( WCC )
• C5 , WC6 and WC9 ( alloy steels cast for high temperatures )
• CF8 ( cast stainless steel 304 ) and CF8M ( cast stainless steel 316 ) for moderately corrosive applications
• LCB ( carbon steel cast for low temperatures )
• LC3 ( alloy steel cast for low temperatures ) For applications with water , steam , compressed air and other less aggressive fluids , cast carbon steel WCB ( Weldable Cast Steel - B Grading ) serves very well for body and bonnet construction . It ’ s important to note that components such as the body and bonnet are generally more tolerant of the corrosive effects of fluids compared to internal components . For applications with superheated steam , the most commonly used body and bonnet construction materials are C5 , WC6 and WC9 ( ferritic alloy steels ). These chromium and
Conventional safety and relief valve and closed-type bonnet
molybdenum-based alloy steels can withstand temperatures as high as 1000 ° F ( 538 ° C ), as per ASME B 16.34 . For internal components such as stem , guide and disc holder in high-temperature applications , the most commonly used material is Monel . Monel is suitable for high temperatures as it prevents component locking due to thermal expansion , in addition to extremely corrosive applications .
Materials for internal components
Internal components such as disc , nozzle , guide , disc holder , adjustment rings , adjustment ring locking screw , stem , bellows ( when applicable ) and spring adjustment screw are typically manufactured from various types of stainless steel . These components require corrosionresistant materials to prevent movement blockage , which could lead to leaks and valve inoperability .
28 Valve World September 2024 www . valve-world . net