Non Return Flanged Valve Factory

The Engineer’s Guide to Flanged Swing Check Valves

Flanged swing check valves are a cornerstone of industrial flow control. Their simple, reliable design allows for the automatic prevention of backflow in a wide array of systems, from water treatment to chemical processing. Their robust construction makes them suitable for high-pressure and high-temperature services, and they are trusted in both upstream and midstream applications.

This guide addresses four critical questions about flanged swing check valves to help ensure you select, install, and specify them correctly for your operation.

Where Are Non-Return Valves Commonly Used?

Non-return valves (NRVs), also known as check valves, are used across nearly every industry to protect equipment and ensure processes run correctly. Their fundamental purpose is simple: they permit flow in one direction and automatically prevent flow from reversing. This automatic operation relies on the velocity of the fluid itself.

Key application areas include:

• Water and Wastewater: Protecting pumps from backflow and maintaining pressure in distribution and treatment systems.
• Oil and Gas: Preventing backflow in pipelines, protecting compressors, and ensuring safe operation in upstream and midstream facilities. Swing check valves are particularly suited for installations where pigging is required.
• Chemical and Petrochemical: Preventing cross-contamination and protecting sensitive equipment from reverse flow in process lines.
• Steam and Condensate Systems: Used to prevent the backflow of condensed water in steam lines, protecting systems against damaging water hammer.
• General Industrial: Found in compressed air systems, boiler feed lines, and heat exchangers to maintain system efficiency and safety.

What Is a Flanged Check Valve, and What Are Its Main Parts and Working Principle?

A flanged check valve is a type of non-return valve that is connected to a pipeline using bolted flanges, which is a common standard for large-diameter and high-pressure industrial piping. The main components of a swing check valve include the body, the disc (or flapper), the seat, and the hinge.

The working principle is straightforward and automatic. Flow enters the valve, pushing the disc off its seat and allowing it to swing open on its hinge. When the forward flow stops or reverses, gravity and the back pressure of the fluid push the disc back onto the seat, sealing the valve and preventing backflow.

Can a Swing Check Valve Be Installed Vertically, or Only Horizontally?

A swing check valve can be installed in both horizontal and vertical piping, but there is a critical condition for vertical installations. The valve must be installed so that flow is moving upward from the bottom to the top.

Therefore, installation in a vertical-down line is not recommended for standard swing check valves. Always ensure the flow direction matches the arrow cast on the valve body.

What Grade of Stainless Steel Is Best for Swing Flanged Check Valves?

The "best" grade depends entirely on the application's service conditions. There is no single answer, but the common stainless steel grades are standard options, with material selection being fully customisable to meet specific project specifications.

Selection Guidance:

• For most chemical and marine applications, 316 (CF8M) is the best choice due to its superior corrosion resistance.
• For general, non-corrosive services like clean water or air, 304 (CF8) can be a cost-effective choice.