How to choose double-blocking pressure relief valve and line blind valve

Choose the appropriate isolation solution: double-blocking pressure relief valve vs. line blind valve

In many industries such as petroleum, line blind valves and double-blocking pressure relief valves (DBB) are important isolation devices.When repairing pipeline lines, we need to choose the best isolation solution for us. line blind valves and double-blocking pressure relief valves are more common choices. This article will compare these two valves and help customers choose the solution that best meets your needs from a practical point of view.

What is a double-blocking pressure relief valve?

The double-blocking pressure relief valve adopts a double-sealed structure. It consists of two valves, which are used as sealing points. It is used to temporarily isolate equipment and lines. It can also quickly isolate specific pipe sections without interrupting the entire process.

This valve system is usually suitable for regular inspections and local maintenance that require frequent opening and closing. Under such conditions, temporary isolation measures are taken. This type of blind valve is easy and quick to use and is very popular in industries with continuous production such as natural gas and oil. The performance of the double block and relief valve itself makes it the best choice for the process.

What is a line blind valve?

Line blind valves physically isolate the line by inserting a solid metal plate (blind plate) to isolate people and machines. Even in extreme cases, it can achieve complete isolation without sealing reliance. Of course, this also makes it the only choice for absolutely safe operation. There are two types of line blinds: traditional types, such as 8-shaped blind plate and tube blanks; and mechanical line blinds, such as quick-cut blind valves and goggles valves, which are faster and safer to operate.

Line blind valves are often used in high-risk conditions, such as chemical processing or hazardous material handling. These areas often involve substances that pose a significant risk to personnel, equipment and the environment, such as highly toxic, flammable and explosive substances. In this case, the absolute isolation provided by the line blind can minimize hidden dangers. They are a good choice, such as operation and maintenance, shutdown or any need to completely isolate system components.

The main differences between double-block and line blind valves:

1. Isolation type:

Double-block and line blind valves rely on valve seals to provide isolation, which can age or fail over time. Line blind valves, on the other hand, can achieve complete isolation by physically isolating upstream and downstream to isolate the connected lines and ensure zero leakage.

2. Description

Double-block and line blind valves are suitable for routine environments that require rapid and frequent isolation, such as inspection, maintenance or testing of small intermediates. On the other hand, line blind valves are well suited for long-term or critical maintenance tasks, many of which are in high-risk situations such as petrochemicals that require absolute isolation.

3. Industry standards

Both double-block and line blind valve devices meet industry standards. Double-block and line blind valves meet API 6D standards, while line blind valves are recognized by API and ASME standards as a reliable isolation method.

4. Leakage risk

Double-block and line blind valves prevent leakage through the integrity of their seals. Over time, seals wear and damage can cause minor leaks, and their effectiveness is not as good as before. The physical barrier of the line blind plate valve can ensure that no fluid or gas can pass through, which completely eliminates this risk and provides the highest level of isolation for safety-critical operations.

Which one should I choose?

Key selection factors: need to start from the working conditions

1. Isolation requirements: If it is temporary isolation such as inspection and minor repairs (such as), then the double-blocking pressure relief valve is preferred to reduce production interruptions; if the equipment is scrapped or major overhauled, then the blind plate valve is more reliable.

2. Characteristics of the medium: If it is a high-risk medium such as high-pressure natural gas: then the physical isolation of the blind plate valve is safer; if it is a conventional medium such as low-pressure water, then the double-blocking pressure relief valve can meet the needs.

3. The trade-off between cost and efficiency: The double-blocking pressure relief valve has a high initial investment, but it can reduce the loss of production suspension; while for the blind plate valve, the procurement cost is low but time-consuming, and it is suitable for scenarios with limited budgets but loose time.

If you are still not sure which device you should use, you can contact our engineers to understand your needs more deeply.