# How to select Double Block & Bleed Valves?

**URL:** <https://forumautomation.com/t/how-to-select-double-block-bleed-valves/12003>\
**Category:** Field Instrumentation\
**Tags:** valve\
**Created:** [April 24, 2024, 1:51pm UTC](https://forumautomation.com/t/how-to-select-double-block-bleed-valves/12003 "2024-04-24T13:51:51Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Rabert](https://forumautomation.com/user_avatar/forumautomation.com/rabert/32/6784_2.png) [@Rabert](https://forumautomation.com/u/Rabert)\
**Post date:** [April 24, 2024, 1:51pm UTC](https://forumautomation.com/t/how-to-select-double-block-bleed-valves/12003/1 "2024-04-24T13:51:51Z")

</div>

Double Block & Bleed Valves are selected based on the following below considerations

 ![7](https://cdn.forumautomation.com/original/2X/1/1d50d93eec740b6464d7129c698646993787ebcf.jpeg)

## 1). Fluid Properties

**Flammability/Hazardous Nature:** Determine whether the fluid under control is combustible or has any other hazards.

**Chemical Composition:** Determine the fluid’s corrosiveness, viscosity, & other qualities.

## 2). Pressure & Temperature

**Operating Pressure:** Calculate the pressure range that the valve will be exposed under normal operation.

**Temperature Range:** Analyze the temperature fluctuations that the valve will see and make sure it can handle them.

## 3). Operational Usage

**On-stream Isolation:** Determine if the valve will be utilized to isolate equipment when the process is running.

**Maintenance Requirements:** Determine whether the valve will be used for maintenance, sampling, (or) flow diversion purposes.

## 4). Industry and Applications

**Oil and Gas Industry:** Recognize the common use of twin block & bleed valves in the oil & gas enterprises.

**Other Industries:** Consider the potential applications of these valves in industries other than oil and gas, including chemical processing, medicines, and power production.

## 5). Bleed Valve Requirement

**Bleed Valve Size:** Install an NPS ½ or bigger bleed valve between the block valves.

**Functionality:** Understand how the bleed valve vents/bleeds the cavity between the seating surfaces & ensures a tight shutdown.

## 6). Operating Requirements

**Product Contamination Prevention:** Determine whether employing multiple block and bleed valves is necessary to prevent product contamination.

**Maintenance and repair:** Determine whether the valve is required to withdraw key equipment from service for cleaning (or) repairs while the unit is still operational.

## 7). Safety Considerations

**Fluid Handling Safety:** Prioritize safety procedures when handling hazardous fluids, particularly in high-pressure (or) high-temperature applications.

**Leakage**  **Management:** Develop solutions for managing and safely withdrawing modest leakage from the upstream valve, ensuring a tight shutdown of the downstream valve.

## 8). System Integrity

**Pipe Isolation:** Determine whether the pipe requires isolation for the maintenance, meter calibration, (or) instrumentation purposes.

**Primary Process Sealing:** To maintain system integrity, ensure that the primary process steam is well sealed against product contamination.

By carefully evaluating these criteria, one can efficiently select double block & bleed valves that meet their individual operational needs and industry standards.

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