Check Valves

Check Valves are the valves which normally allow the fluid (liquid or Gas) to flow through it in only one direction & hence they are also called as Non-return valves or One way valves or Clack valves.

Check valves are of two ports valves, one for inlet and other for outlet. There are various types of check valves, used in a wide variety of applications. Check valves work automatically with the fluid parameters. Check valve are not controlled by any person or any external control like any type of actuator. They do not have any valve handle or stem.
An important concept of the check valves are the Cracking Pressure which is the minimum upstream pressure at which the valves will operate. Typically, the check valves are designed for and can therefore be specified for a specific cracking pressure.

Check valves are helping the pumps to discharge flow smoothly without any additional load or uneven hammering to pump impellers. Check valves are also often used when multiple gases are mixed in to one gas stream. A check valve is installed on each of the individual gas streams to prevent mixing of gases in the original sources. For example: if a fuel and an oxidizer are to be mixed, then check valves will normally be used on both the fuel and Oxidizer sources to ensure that the original gas cylinders remain pure and helping to be nonflammable – safety.

There are various types of check valves : viz.

• Swing Check Valve or tilting disc check valve – the movable part as disc swings on a hinge or trunnion, allowing the inlet fluid and blocking the returning of flow towards inlet. Disc is working as leak proof seat on the inlet port from inside so that with the help of fluid pressure it allows to flow, but with the help of return flow pressure it blocks the flow towards inlet. The stroke of this swing disc can be controlled by external screw stopper mechanism to control the flow as well.
• Lift Check Valve – the plug is seating on a port after inlet towards outlet side.
• This also works with the help of pressure same as swing check, the plug is getting lift upward and allowing the fluid to pass through and closing the port with the returned fluid pressure.
• Ball check valve – there is ball in place of plug and working same function as lift plug.
• Ball check with Spring loaded or plug check with spring loaded are also provided where the pressure difference is too low and spring will help to keep it in shut position.

Features :

• Check valves with the clapper design features either a standard coating or the superior
• abrasion resistance and acid resistance coating to give longer operative life in corrosive
• application.
• The rugged valves operate at working pressure of 6000 to 20,000 psi in well service
• applications such as acidizing, cementing, fracturing and energized fluids.
• Some of the check valves are manufactured from solid forgings to maximize strength and
• abrasion resistance.

Check valves are available in various configurations including standard flow –

• Wing-ahead or reverse flow – thread-ahead types and are color coded for convenience and safety.

• Non Slam Nozzle Check Valves :
• Minimum pressure loss through optimized flow cross sections.
• Flow optimized valve disc and valve sealing ring.
• Optimum hydraulics with short closing path to minimize water surge.
• Wide area of applications due to compact form, any possible assembly position and adjustable spring strength.
• Swing Check valves designed: with degree of opening from 93% to extremely low zeta value.
• Self-centering valve disc through spherical bearing pin, therefore always tight closure.
• Medium-free shaft bearing for permanent easy running.
• Transparent plastic protective cage in the pivoting area of the lever and weight to protect
• against un-international contacts.
•  Practice-proven, weight saving short design.
• Double-eccentric, freely swinging and flow optimized tilting disc.
• Shafts born in maintenance-free, self-lubricating sleeve bearings.
• Rolled in, Solid sealing ring of body, seating ring of the tilting disc with elastic fine sealing.
• Also available with weight loaded hydraulic actuators.
• Available with Rubberized tilting disc for rapid and silent closing on flow reversal.
• Wafer type Double Wing Version Check Valves:
• Design simple and robust as well as extremely short type.
• It can be used in horizontal as well as vertical pipelines as it is spring loaded.
• Ball Check Valves:
• No mechanically moving parts, therefore extremely easy to maintain.
• Insensitive to mud.
• Low flow resistance in the open position due to ball curvature.

Specifications :

• Face to Face Length EN 558-1, S.48 (DIN 3202 F6) & ANSI B16.10
• Marking Standard EN19.
• Inspection and Testing : API 598, API 6D, 12266-1 and BS 6755.
• Approval to PED/97/23/CE and WRAS available.
• Standard: BS EN 1074 Pt.3:2000, BS EN 12334:2001 and BS 5153:1974
• Flange and Drillings : BS EN 1092-2:1987 Table 9 (PN16), Table 8 (PN10),
• BS10 Table D or E, ASME B16.5, ASME B 16.47 A & B, MSS SP-44 & API 605
• Butt weld end dimensions ASME B16.25
• Wall Thickness Dimensions : API 600 and BS1868

• Pressure Temperature Ratings : ASME B16.34
  
  • Check Valves design, Wall thickness are comply with API 594 and API 6D and
  • Face to Face comply with API 594, API 6D and EN 558-1
  • Valves marking comply with API 594, MSS SP-25 and ASME B16.34
  • Valve Inspection comply with API 594 and API 598

• Valves : Flange – Temperature and pressure comply with :
  
  • ANSI B16.10, DIN ISO-7005-1/2 BS 4504 and JIS B2239 – for Cast Iron.
  • ANSI B16.42, DIN ISO-7005-1/2 BS 4504 and JIS B2239 – for Ductile Iron.
  • ANSI B16.5 – Size: 1-1/2” to 24” & ANSI B16.47 series A(MSS SP-44) for Size: 26” to 60”– for Carbon Steel , Stainless Steel and Alloy Steel.
  •  DIN ISO-7005-1/2 BS 4504 and JIS B2220 – for Carbon Steel , Stainless Steel & Alloy Steel.

Various types of Check Valves :

• Horizontal Swing Check Valves.
• Lever and Weight Swing Check Valves.
• Elastic Swing Check Valves with or without Back flow
• rod – control attachment.
• Lift Check Valves (Piston Check Valves).
• Spring Loaded Piston Check Valves.
• TIG Welded SS Spring Check Valves.
• Wafer Swing Check Valves.
• Dual Plate Spring Loaded Wafer Check Valves.
• Wafer disc Check Valves.
• Rubber Lined OR Other Lined Ball Check Valves.
• Silent Wafer Check Valves.
• Silent Globe Check Valves.
• DRV- BN Nozzle Check Valves.
• Fire Alarm Check Valves.