Globe Valve Vs Ball Valve (Comprehensive Analysis)

What Is A Globe valve?

Globe valves are indispensable fluid control devices in piping systems. Their operating principle is based on the vertical movement of the valve flap along the center line of the valve seat. 

In terms of technical parameters, the flow coefficient CV of the globe valve has an approximately linear relationship with the valve opening, showing a fast-opening characteristic, which is conducive to precise adjustment. 

Modern globe valve design incorporates several advanced technologies, such as intelligent actuators, carbide coatings, CFD analyses and 3D printing technology. These innovations have not only improved the performance and reliability of the valves but also realised intelligent functions such as remote control and condition monitoring. For example, the -196°C class cryogenic globe valve used in the LNG transmission system is made of deep-cooled austenitic stainless steel to ensure reliable operation under extreme conditions.

Disadvantages Of Globe Valve

However, globe valves are not perfect. In the actual use of the process found that they are fully open or fully closed state of the best results, and partially open when the medium may be caused by high-speed flow valve vibration, and the valve valve and the valve seat may form a cavity between the valve, resulting in cavitation phenomenon, increasing the wear and tear of the valve and noise.

Globe valve flow path is ‘Z’ shape, easy to cause a large local pressure loss, will lead to its CV is usually lower than the same diameter of the ball valve and gate valve. And because the valve needs to overcome the medium pressure and sealing surface friction, opening and closing the required operating torque is larger.

Ball valve is a kind of valve widely used in fluid control system, involving civil and industrial use. Its core component is a spherical spool with a through hole. The working principle of the ball valve is based on the 90-degree rotation of the sphere, through the control of the sphere in the channel and pipeline alignment to achieve open, close or regulate the fluid flow and other states.From the technical parameters, the ball valve has excellent performance indicators. Its pressure rating is up to PN420 (ANSI 2500 class).

The structure of the ball valve mainly includes the valve body, ball, seat, stem operating mechanism, and other components. According to the structure of the ball and seat, it can be divided into floating ball design and fixed ball design. The floating ball design can achieve self-sealing under high-pressure differential conditions, while the fixed ball design is suitable for larger-diameter and higher-pressure occasions. Ball valves are available in a variety of drive modes, including manual, pneumatic, electric hydraulic, etc., which can be selected according to different application requirements.

In practice, ball valves show a variety of advantages. First of all, its quarter-turn operation mode makes the switch quickly, especially suitable for the need to quickly cut off the occasion. Secondly, when fully open, the flow path is smooth and the pressure loss is small, which is especially important in large-diameter long-distance pipeline. Furthermore, the ball valve sealing performance is excellent, two-way sealing ability, suitable for a variety of media.

Disadvantages Of Ball Valve

However, the ball valve also has some limitations. For example, in regulating applications, the flow characteristics of ordinary ball valves is not as ideal as the regulating valve, although it can be improved by V-shaped notch ball, but there are still some limitations. In addition, in the medium containing solid particles, the sealing surface of the ball valve is susceptible to wear and tear, the need to choose a special material or structure of the ball valve.

Internal Structure And Mechanism:

Globe valve CV is relatively low compared to the ball valve, full bore design of the ball valve flow coefficient Cv can reach more than 95% of the gate valve of the same caliber, while the globe valve can only reach 60-70% of the intrinsic flow characteristics of the fast-opening characteristics, the flow rate of small openings change drastically. The flow characteristics of the ball valve is close to equal percentage characteristics, more suitable for flow regulation.

Pressure Loss:

Globe valve due to the ‘Z’ shaped flow path, local pressure loss, pressure loss coefficient ζ is usually between 4-6. The ball valve is fully open when the flow path is smooth, the pressure loss is small, ζ is usually between 0.1-0.3.

Sealing Performance:

Globe valves are available with API 598 Class VI seals, and metal seals are available up to Class IV or Class V.

Ball valves are available with soft seals up to API 598 Class VI seals and metal seals typically up to Class V seals.

Temperature Range

Metal Sealed Globe Valves are available for temperatures from -196°C to 550°C.

Soft-sealed ball valves are normally suitable for temperatures from -29°C to 180°C, metal-sealed ball valves can be extended to -196°C to 450°C

Working

Globe valves use the valve flap along the centre line of the valve seat of the linear lift movement to control the fluid, through the mandatory seal to achieve media cut-off. Ball valves use the ball of 90 degrees to control the fluid, a quarter of the rotation can be completed full open or full closed.

Application Scenario：

Globe valves are suitable for occasions requiring frequent adjustment, commonly used in steam, high-temperature and high-pressure systems.

Ball valves are suitable for the need for rapid cut-off occasions, widely used in petroleum, natural gas, chemical industry, and other fields.

Installation Position Of Globe Valve

Globe valves can be installed in any position on vertical or horizontal pipework, but are best installed with the valve stem vertically upwards. Installation with the stem pointing downward is strictly prohibited and may result in degraded performance and shorter valve life. When installing the valve, it must be noted that the direction of fluid flow is the same as the arrow on the valve body, and usually, the fluid should enter from the bottom of the valve seat. For globe valves with electric actuators, special care should be taken to install the valve stem vertically upwards and to provide adequate shelter in outdoor installations.

In addition, excessive pipeline stresses on the valve body should be avoided during installation and additional support should be provided for large-diameter valves (DN > 100 mm). For installation on long straight sections, the effect of temperature variations should also be taken into account and fixed supports or axial compensators may be required.

It is important to note that the direction of installation of the globe valve must be confirmed and not reversed. Reverse installation can lead to a series of serious consequences, including reversal of the direction of water flow, unstable temperature control, accelerated wear of equipment, flow regulation failure, increased safety hazards, reduced system efficiency, maintenance difficulties, and the potential risk of media leakage.

Comprehensively speaking, different scenarios, different business needs often need to be able to perfectly match the valve. If you have a special industry, and still can not determine how to choose the right valve, welcome to contact our valve manufacturing experts at any time, we will give you tailored product solutions to meet your specific needs, just enter your information, click to send can be, ready to serve you!