Piping systems will undergo pipe abandonment for several reasons. That’s because pipes do have a useful lifespan and may need upgrading over time. However, simply letting an abandoned pipe be isn’t a good idea as it can create safety and environmental hazards.
What Is Pipe Abandonment?
When a pipeline reaches the end of its useful life and needs to retire, it needs to be abandoned and decommissioned. These allow for pipeline disassembly and prevent them from becoming hazards. Pipe abandonment involves a series of deactivation procedures that involve eliminating the transported materials. It also includes the termination of supply connections.
Pipe Abandonment vs Pipe Decommissioning
Despite their similarities, pipe abandonment and decommissioning are not the same. What is the difference between abandoned and decommissioned pipelines?
Firstly, pipeline decommissioning is a series of necessary planned activities to remove pipelines and make them inactive safely. It ensures that each component of a pipeline or network is safely neutralized. Decommissioning may involve cleaning, purging pipeline contents, and pipeline removal. It may also allow for leaving the pipeline in place but making them inoperable.
Meanwhile, pipe abandonment refers to the process of stopping and eliminating all fluids conducted during the service life of the pipeline. Moreover, it involves terminating a pipeline’s connections to active production channels and facilities.
The key difference between these two processes is that decommissioning gives leeway for pipeline recovery. Meanwhile, pipe abandonment does not leave the option open and entirely abandons the pipe. In some instances, decommissioning may be a precursor to abandonment.
How to Decommission and Abandon Pipes
What happens to decommissioned pipelines? How does pipe abandonment work, and how do you decommission a pipeline? Here are the processes involved in the decommissioning and pipe abandonment procedure.
1. Disconnection from Supply Sources
Pipeline operators must disconnect the flow lines of the pipeline scheduled for abandonment. They must disconnect it from transport elements, gas reservoirs, and other storage components. This is a vital part of the process as it ensures the safety of the transition from active to inactive.
2. Pipeline Purging
The pipelines must be purged using inert gas, preferably nitrogen. This forces any residual gas or oil out of the pipeline network. It also reduces the risk of explosions and fires from the abandoned pipe by eradicating these materials and inerting flow lines.
3. Pipe Abandonment in Place (In-Situ)
It’s not easy to abandon an underground pipe and remove it at the same time. There are instances wherein leaving an inactive pipeline in place is the ideal solution. At first, this may seem ill-advised as it can cause water ingress, soil destabilization, and subsidence. However, with proper procedure, these can be avoided.
The pipelines that are left in place must undergo measures to eliminate explosion and fire hazards. These pipes will undergo cleaning and flushing before they can be disconnected from the gas and oil supplies. Afterward, these abandoned pipes will be sealed at both ends.
4. Pipeline Grouting
Voids in concrete can be hazardous and cause deterioration. Similarly, abandoned pipes effectively create a void underground, introducing water flow and making the ground prone to subsidence and destabilization. That’s why, as it is with concrete pressure grouting, filling or grouting abandoned pipes may be necessary.
The operators often use a cementitious slurry or grout. Some may also use polyurethane foam to fill the abandoned pipes. In doing so, the pipe is less prone to deterioration and subsidence. It’s more cost-effective and requires less manpower than pipeline removal.
5. Pipeline Removal
As the name suggests, pipeline removal involves physically taking away the abandoned pipeline. However, it’s not necessary for all structures. That’s because some can still be reserved for restoration and reuse. Typically, flow lines above ground are reserved for pipeline recovery.
Apart from the potential for reuse, pipeline removal has several drawbacks. For one, it’s more expensive and requires a lot of manpower. It also increases the risk of environmental and safety hazards during the process. Finally, it may disrupt the surrounding ecosystems as the residual contents may leak and contaminate the area.
Eliminate Safety Hazards
Pipe abandonment is an essential part of retiring an old pipeline. It prevents soil destabilization and can reduce the potential for environmental problems. Moreover, it effectively reduces water ingress when the pipes are properly filled or grouted. It’s in the best interest of not only the pipeline operator but also the general public.