How to isolate areas for hot work on pipelines

When performing hot work on pipelines, if it is not possible to install blind flanges for isolation, the following methods can be considered: 1. Gas displacement: Use nitrogen or other inert gases to displace the combustible gases or oxygen inside the pipeline, ensuring that the environment within the pipeline does not support combustion. 2. Water seal isolation: Fill water on both sides of the work area to create an effective barrier utilizing the incompressibility of water. 3. Use pipe clamps for sealing: Apply special pipe clamps on both sides of the area where welding is to be performed to prevent gas flow. 4. Use movable isolation devices: such as pipe-sealing air bags or mechanical pipe sealers for temporary sealing. Choosing the appropriate isolation method requires decision-making based on the specific conditions at the site and a safety assessment. At the same time, ensure that all safety measures are in place and conduct strict safety inspections. .

First, the pipeline replacement must be completed successfully; then, the commonly used method is to install blind flanges. As shown in the diagram, by closing the two main valves and fully opening the discharge valves at those two points, along with the use of online monitoring, safety during construction can generally be ensured. However, according to the regulations, a blind plate should be added for reference.

Normally, clearance isolation or the use of blind flanges is employed to achieve absolute physical separation; if this is not possible, check your company’s regulations to see whether an approval for a work plan can be obtained, or whether deviation management procedures can be applied.

Or the lower seal may get blocked, which poses certain safety risks