Globe Valves - BS 1873

Flowtorq Engineering is best manufacturer of globe valves. A globe valve, different from gate valve or ball valve, is a type of valve used for flow control or regulating flow in a pipeline. It is designed as per BS 1873 and BS 5352 standards. It consists of a movable plug or disc element and a stationary ring seat in a generally spherical body. Globe valves are named for their spherical body shape with the two halves of the body being separated by an internal baffle. This has an opening that forms a seat onto which a movable plug and can be screwed in to close (or shut) the valve. The plug is also called a disc. In globe valves, the plug is connected to a stem which is operated by screw action using a handwheel in manual valves. Typically, automated globe valves use smooth stems rather than threaded and are opened and closed by an actuator assembly.

Function

Globe valves are widely used for flow control (regulation) and also for ON-OFF duty. When fully open, the typical globe valve has little obstruction in the flow path, resulting in very flow resistance which results into easy flow regulation. The size of the flow path generally varies in a nonlinear manner as the globe disc is moved. This means that the flow rate does change evenly with stem travel and the varying area of flow from seat vs plug. Depending on the construction, globe discs are usually avaible in disc type, plug type, ball type and cage type for critical flow applications.

Operation

Common globe valves ( BS 1873 and BS 5352) are actuated by a threaded stem that connects the actuator (e.g. handwheel or motor) to the disc or plug. They are characterised as having a rising stem. Rising stems are fixed to the disc and rise and lower together as the valve is operated, providing a visual indication of valve position. The actuator is attached to a nut that is rotated around the threaded stem to move it. The actuator are often are threaded into the stem from top. They may have a pointer threaded onto the stem to indicate valve position, since the stem motion can be viewed from outside. Globee valves may have flanged ends drilled according to pipeline-compatible flange dimensional standards. Sometimes globe valves are butt welded on pipelines. Globe valves are typically constructed from cast iron, cast carbon steel, ductile iron, gunmetal, stainless steel, alloy steels, and forged steels. For flow regulation, this usually depends on the area of opening between disc and seat or plug and seat often. This area varies as the stem moves up and down as a result of valve operation. The varying area results in flow control which is usually calculated and termed as 'Valve CV' also known as 'Co-efficient of Flow Value".

Cast Steel Globe Valve as per BS 1873

Construction of Globe Valves as per BS 1873

Bolted Bonnet & Welded Bonnet

Bonnets provide leakproof enclosure for the valve body. Globe valves may have a screw-in, union, or bolted bonnet. A screw-in bonnet is the simplest, offering a durable, pressure-tight seal and are used for smaller sizes normally. A union bonnet is suitable for applications requiring frequent inspection and cleaning. It also gives the body added strength. A bolted bonnet is most widely used for larger valves and higher pressure applications. Bolted bonnet is widely used for sizes 2 inch and above. Often welded bonnet is used where the valves are buried or zero leak at longer service durations are required. These design aspects are specified in standards BS 1873 and BS 5352.

Pressure seal bonnet

Another type of bonnet construction in a globe valve is pressure seal bonnet. This construction is adopted for valves for high pressure service, typically in excess of 2250 psi (15 MPa). The unique feature of the pressure seal bonnet is that the bonnet ends in a downward-facing cup that fits inside the body of the valve. As the internal pressure in the valve increases, the sides of the cup are forced outward. improving the body-bonnet seal. Other constructions where the seal is provided by external clamping pressure tend to create leaks in the body-bonnet joint.

Applications

Industrial applications such as oil and gas, petrochemicals, chemical, power generation, mining and industries use this valves. What makes this useful is that its ability of flow control. Additionally, there is also a pre calculated pressure drop which is as per the flow requirements of process.

Why Select and Use Flowtorq Globe Valves ?

Easy Availibility
Wide range of flow control capability and application range
Good for critical processes
Economic Cost
Wide Range of Size from 1/2" (half inch) to large sizes
Wide Range of pressure rating capacity from 150# low pressure to 2500# high pressure and above
Easy Operation
Easy Maintenance and handling
Rigid and Robust Construction
Wide Variety of internal trim parts variants
Long Service Life
Can be used for flow control and ON-OFF as well.

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bs 5352 valves

General Technical Specifications

Size Range – 1/2″ to 16″
Pressure Rating – 150#, 300#, 600#, 800#, 900#, 1500#
Certifications – IBR, CE, etc.
Inspected & Witnessed By third party agencies
API Valves, ATex Valves, CE Valves, Process Valves, Gas Valves, Water Valves, Cryogenic Service, Fire Safe