SPECIAL TOPIC : SEVERE SERVICE APPLICATIONS
many metals . Materials like Monel ( nickelcopper alloy ), Hastelloy , and Titanium are preferred for their resistance to chlorine corrosion , especially in dry environments . Stainless steel , while common in other industries , is typically avoided in chlorine service due to its susceptibility to stress corrosion cracking ( SCC ) when exposed to chlorine , particularly in moist environments .
Stress Corrosion Cracking ( SCC ) in Chlorine Service
SCC is a primary concern when using certain metals in chlorine service , especially in the presence of moisture . SCC can cause cracks to form and propagate in stressed materials , leading to potential valve failures . This is why materials such as Monel and Hastelloy are commonly recommended to minimize this risk in chlorine environments .
As outlined in the Chlorine Institute Pamphlet 6 , valves for chlorine service must undergo a rigorous process to ensure they are free of contaminants before they are shipped or installed . This process includes :
1 . Oven Drying Process
Valves are often dried in an oven to ensure that all residual moisture is removed . Moisture can react with chlorine , forming corrosive acids that lead to rapid valve degradation .
2 . Clean Room Assembly
To prevent contamination during assembly , valves are frequently assembled in a clean room environment . This ensures that no moisture , dust , or oils are present , which could otherwise react with chlorine and cause operational problems . The valves are then sealed with inert gas , such as nitrogen , to maintain their cleanliness during storage and transport .
3 . Pressure and Leak Testing
After assembly and drying , valves are tested to ensure they can handle the pressures expected in chlorine service . Helium leak testing or dry nitrogen testing is commonly used to ensure no moisture or leaks are present . Proper testing is essential for safe operation in these environments .
Final Cleaning and Installation Procedures
Following the processes outlined above , valves must be sealed and shipped in protective packaging to prevent contamination during transport . Upon arrival at the installation site , valves should be inspected and cleaned again to ensure they remain free from moisture and other contaminants .
Proper material selection and strict adherence to assembly , drying , and sealing procedures , as recommended in industry standards like Pamphlet 6 , are crucial when handling valves for chlorine service and using corrosion-resistant materials can help prevent stress corrosion cracking . Following these procedures ensures valves will operate safely and effectively in chlorine environments .
Conclusion
Severe service valves are more than just a piece of equipment — they are the backbone of industrial systems where there is no room for error . When working with Hydrofluoric Acid , hydrogen , or chlorine , these valves take on the harshest conditions , enduring the extremes of pressure , temperature , and corrosion . The stakes are high , and the consequences of valve failure can be catastrophic . That is why getting it right from the start is so important .
It is not just about choosing the right materials or following the industry standards but understanding how each specific environment impacts performance and safety . From material selection to testing protocols , every detail matters when dealing with severe service valves . The right decisions up front can prevent leaks , failures , and , ultimately , major disruptions to operations .
For those in this field , it is clear : the work
ABOUT THE AUTHORS
that is put into valve design , material compatibility , and maintenance is not just about compliance . It is about safeguarding people , protecting the environment , and ensuring that systems run smoothly . These valves are not just critical components , they are the key to maintaining operational integrity in some of the toughest industries out there .
At the end of the day , investing time and resources into understanding specific service conditions pays off . Whether it is adhering to the guidelines of API RP 751 for Hydrofluoric Acid , ensuring the hydrogen valves resist embrittlement , or following the meticulous procedures outlined in Pamphlet 6 for chlorine service , the importance of staying diligent cannot be overstated . By focusing on the details , operators can ensure their valves continue to perform safely and reliably , keeping their systems — and team — out of harm ’ s way .
Foster Voelker II attended the University of Houston , receiving a degree in Mechanical Engineering . After graduation , Foster Voelker began his career as a valve engineer for a large commodity valve manufacturer . He is the Director of Engineering for William E . Williams Valve Corporation .
Mike Dunn is an alumnus of Northeastern State University , receiving a Bachelor of Science in Management Information Systems . However , deviating from the most obvious professional path , Mike decided to uphold the family legacy and enter the illustrious valve repair industry . Almost two decades later , Mike is the co-owner of JS Machine and Valve Inc .
6 Valve World Americas | November 2024 • www . valve-world-americas . net