Cast Steel Bolted Bonnet Gate Valves

 

Design Features & Benefits


CNI cast steel bolted bonnet gate valves are designed and manufactured to provide maximum service life and dependability. All gate valves are full ported and meet or exceed the design requirements of ASME B16.34. Valves are available in a complete range of body/bonnet materials and trims.

Cast Steel Bolted Bonnet Gate Valves - Design Features and Benefits


 Range of Materials

Standard body/bonnet materials include ten grades of carbon, low alloy and stainless steels. For special applications they can be supplied in other grades of alloy and stainless steel. There’s a full range of trim materials to match any service. Optional packing and gasket materials are available for a full range of service conditions.

Actuator Flexibility

All valves are available with hand-wheels, gearing, electric motor actuators or pneumatic or hydraulic cylinder actuators.
 

Easy Maintenance

By providing a choice of wedge types, the valve can be matched up with the service conditions, thus enhancing operability and lessening the possibility of binding. Full body wedge guides assure wedge-to-seat alignment.
 

 Easy Operation

Threaded or welded seat rings are easily accessible for repair or replacement. Packing swing bolts on most valves simplify packing replacement. All CNI bolted bonnet designs facilitate fast disassembly.

Longer Life

Rugged construction provides years of reliable service. T-head stem/wedge design permits the wedge to self-align for extended seat life. A two piece packing gland prevents cocking and stem damage.
 

 

 

Choice of Wedge Types

CNI cast steel bolted bonnet gate valves are available with a selection of wedge types to match operating service conditions.  Specify the type best suited to your service conditions.



Solid Wedge

Cast Steel Bolted Bonnet Gate Valves - Choice of Wedge Types - Solid Wedge This is the most common wedge type. It is also the strongest, simplest and most economical of the various wedge types. The advantages of this wedge are that it is highly resistant to corrosion and vibration. Disadvantages are that it is not self-compensating to seat distortion caused by high temperature thermal expansion or bending moments applied to the valve by piping loads which may cause the wedge to stick in the seats.

 Flex Wedge

Cast Steel Bolted Bonnet Gate Valves - Choice of Wedge Types - Flex WedgeThe flex wedge is cast or machined with a circumferential groove to  allow the seating faces to move independently and adjust to movement of the body seats. It is used where line loads or thermal expansion of the system is likely to distort the seat face in the valve. The flex wedge is especially useful to prevent sticking where valves are closed when hot and opened when cold. This type of wedge is ideally suited for steam or other high temperature services.

Split Wedge

Cast Steel Bolted Bonnet Gate Valves - Choice of Wedge Types - Split WedgeThe split wedge provides complete flexibility between the two halves of the wedge to compensate for seat distortion, especially in light weight, low pressure valves. This style is also used for high pressure gas or corrosive services. It is not recommended for high velocity flow or services where suspended particles can foul the wedge.

 

Because of the complexity of this design, it is generally more expensive than the solid or flex designs.

High Integrity hutoff Wedge

Cast Steel Bolted Bonnet Gate Valves - Choice of Wedge Types - High Integrity Shutoff WedgeFor services that require bubble tight shutoff, the High Integrity Shutoff (HIS) design is the best option. This design provides a zero leakage barrier on both upstream and downstream seats. A full range of trim and shell materials are available for corrosive service and temperatures up to 450°F.

 

 

Standard Bonnet Joints

Body/bonnet joints on CNI valves are designed for rugged services with a more than adequate number of bonnet bolts.
The standard joint varies, depending on valve class. These standard joints are shown.

Class 150

Cast Steel Bolted Bonnet Gate Valves - Standard Bonnet Joints - Class 150The standard, flat, oval bonnet joint is the simplest and most economical configuration for low pressure services and is required to maintain ASME face-to-face dimensions on Class 150 valves sizes 4"-36". Our standard gasket is made of corrugated metal, but flat gaskets in other materials are available when specified. 1½" through 3" valves are furnished with a circular male and female bonnet joint and spiral wound gasket

Class 300 and up

Cast Steel Bolted Bonnet Gate Valves - Standard Bonnet Joints - Class 300The circular male and female bonnet joint fully encapsulates the gasket. Typical gasket types are spiral wound or double jacketed.

 

 


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