Common Valve Applications in the Petroleum Industry

Valves are essential components in the petrochemical industry, serving various crucial functions in pressure piping systems. They are responsible for tasks such as cut-off, regulation, conduction, backflow prevention, pressure stabilization, diversion, overflow, and pressure relief. Due to their complex structure and high technological content, valves are considered the most intricate components in pipelines, typically assembled from multiple parts and components.

Valves are extensively used across petrochemical and chemical plants. The cost of pipeline materials makes up about 15% to 20% of the total project investment, with valves and piping together accounting for about 50% of this cost. Specifically, valves represent over 50% of this expenditure. In refinery installations, the distribution of various types of valves is as follows: gate valves make up 80%, globe valves 8%, and check valves 6%, making these three types the most commonly used in petrochemical production units. Other types of valves account for the remaining 6%. The investment in valves constitutes about 5% to 8% of the total device cost. For instance, in a 2.5 million tons/year normal decompression unit and a 1.4 million tons/year catalytic cracking unit, valve specifications are distributed as follows: 3% for DN ≥ 400, 12% for DN150350, 25% for DN50100, and 60% for DN ≤ 40.

Here are several common valves used in the petroleum field:

01 Gate Valve

Gate valves, also known as sluice valves, are extensively used in various applications. Their closing mechanism involves the sealing surface of the gate and the valve seat being highly polished, flat, and well-matched to prevent the medium from passing through. This sealing effect is enhanced by the top of the mold, a spring, or the gate's shape. The primary function of a gate valve is to cut off the flow in the pipeline.

Advantages of gate valves include their low fluid resistance, low energy requirement for opening and closing, and suitability for bidirectional flow without any directionality. When fully open, the sealing surface is less prone to erosion. Additionally, their short structural length makes them ideal for both small and large valves.

Gate valves can be categorized based on the stem threads into two types: rising stem and non-rising stem. They are also divided into two types based on the gate structure: parallel and wedge.

02 Globe Valve

The globe valve, also known as the stop valve, is one of the most widely used types of valves. Its popularity is due to the minimal friction between sealing surfaces during the opening and closing processes, which makes it more durable. Additionally, the valve has a relatively low opening height, is easy to manufacture, and requires straightforward maintenance. Globe valves are suitable for both low and high-pressure applications.

The closing principle of a globe valve relies on the pressure exerted by the valve stem, which forces the valve's sealing surface against the seat's sealing surface, thereby preventing the flow of the medium.

Globe valves are unidirectional, allowing the medium to flow in only one direction, which necessitates directional installation. Compared to gate valves, globe valves have a longer structural length and higher fluid resistance. Over extended periods, their sealing reliability can be less robust.

Globe valves can be categorized into three types: straight-through, right-angle, and straight-through inclined globe valves.

03 Check Valve

A check valve operates automatically, relying on the fluid's own force to open and close, preventing the backflow of the medium. It is also known as a non-return valve, one-way valve, or clack valve. Check valves can be divided into two main types based on their structure.

The lifting check valve moves along the vertical centerline of the valve body. This type includes horizontal lifting check valves, which are installed in horizontal pipelines and have a valve body shape similar to a globe valve, and vertical lifting check valves, which are installed in vertical pipelines.

The other type is the swing check valve, where the valve rotates around a pin located outside the seat. This type includes single, double, and multi-valve configurations, all operating on the same principle. Additionally, a special type of check valve is the bottom valve used in pump suction pipes. It is similar in structure to the lifting and swing check valves but has an open lower end to allow water entry.

04 Butterfly Valve

The butterfly valve, true to its name, features a key component that resembles a butterfly flapping in the wind, allowing free movement. The valve disc, shaped like a disk, rotates around an axis within the valve seat. The angle of rotation determines the valve’s degree of opening and closing.

Butterfly valves are known for their lightweight design and material efficiency compared to other valves. They have a simple structure, enable rapid opening and closing, and can be used for both cutting off and throttling flow. They also offer low fluid resistance and ease of operation. Additionally, butterfly valves can be manufactured in large sizes. Due to their economical nature and superior adjustability, butterfly valves are often preferred over gate valves, especially in hot water pipelines where they are widely used.

05 Ball Valve

The ball valve operates by rotating a ball within the valve body to open or close the flow. It features a light switch action, compact size, and can be manufactured in large diameters. Ball valves are known for their reliable sealing, simple structure, and easy maintenance. The sealing surface and ball are often in a closed state, making them resistant to erosion by the medium, which has led to their widespread use across various industries.