Frequently Asked Questions

What is the primary function of a Non-Slam Check Valve?

A Non-Slam Check Valve is engineered to prevent reverse flow and mitigate water hammer in critical service applications. Its disc is designed to close rapidly and quietly before significant reverse flow velocity can develop, protecting pumps, pipes, and other upstream equipment from damaging pressure surges and shock.

What is the role of a Diaphragm Valve in slurry service?

A Diaphragm Valve excels in slurry service due to its isolated design. The diaphragm separates the valve's mechanical components from the abrasive and corrosive fluid, preventing clogging and wear. This provides a reliable, leak-free seal and ensures smooth operation when handling fluids with suspended solids.

What is the key functional difference between a Gate Valve and a Globe Valve?

A Gate Valve is designed for on/off isolation with minimal pressure drop, offering a straight-through flow path. A Globe Valve, however, is engineered for throttling and precise flow regulation. Its internal Z-shaped path allows for accurate control but results in a higher pressure drop compared to a gate valve.

When are ASME B16.5 flanges applicable and how do Class ratings work?

ASME B16.5 covers pipe flanges and flanged fittings from NPS 1/2 through NPS 24. Class ratings (150, 300, 600, 900, 1500, 2500) define pressure–temperature limits by material group. The allowable pressure reduces as temperature rises. Always verify material group number, gasket type, and bolt materials for the specified service.

When is a Modulating Control Valve used over a standard ON/OFF valve?

A Modulating Control Valve is used when precise control over the flow rate or pressure is required, rather than simple shutoff. It can be positioned at any point between fully open and fully closed to accurately regulate process variables, making it essential for applications requiring dynamic process control.

Which material should I choose: SS304 vs SS316 vs SS316L vs SS904L vs WCB vs Brass?

SS304: general corrosion resistance, food/pharma utilities. SS316: added Mo for chlorides/sea spray. SS316L: low carbon for improved weldability and reduced sensitization. SS904L: high Ni/Cr/Mo for aggressive chloride media. WCB: carbon steel for general service where corrosion is controlled by lining/inhibitors. Brass: potable water and air, avoid ammonia/sour service.

How do I estimate valve size using Cv?

Cv relates flow to pressure drop: Q = Cv · sqrt(ΔP / SG) for liquids (US gpm). Start with process flow and allowable ΔP. Select a body size where rated Cv is 20–80% utilized at design for good controllability. For gases/steam, use appropriate compressible flow equations and verify choked flow limits.

What is the difference between ANSI and ASME references like ANSI 150 vs ASME Class 150?

Modern flange standards are maintained by ASME (e.g., ASME B16.5). "ANSI 150" is often used informally to mean ASME Class 150. Always specify the correct ASME designation in documentation and procurement.

What is IBR and where is it applicable?

IBR (Indian Boiler Regulations) applies to components used in boiler and steam service in India. If your application requires IBR compliance, ensure procurement specifies IBR-approved makes and documentation. This is a regulatory topic; it does not imply supplier certification.