All onshore pipelines should be removed unless buried to a minimum of 3 feet below the surface, in which case abandonment-in-place may be an alternative. Where national, regional or local regulations and requirements, concession terms and contractual
agreements, or permit requirements allow abandonment-in-place at depths shallower than 3 feet, a risk assessment should be performed to confirm that abandonment-in-place is sufficiently protective of the Company’s interests from all perspectives,
including HSE, business, social, and reputation. If the risk assessment confirms that abandonment-in-place is sufficiently protective of the Company’s interests then an exception procedure is not required. For onshore facilities, minor equipment,
piping and appurtenances (and subsurface infrastructure) associated solely with pipeline operation and safety may be decommissioned and removed with the pipeline.
- Plan the pipeline abandonment, including isolation, draining, pigging, flushing, contents disposal, removal versus abandonment-in-place, and reclamation and restoration of impacted areas. Perform site visits, surveys, content-sampling, survey-map
reviews, etc., as needed, as well as identifying in-line valves, repair locations, pipeline crossings, dead legs or other features that may require mitigation procedures.
- Pipeline right-of-way agreements should be reviewed for special requirements, and to verify that the agreement will not be violated or that Company rights will not be unintentionally relinquished.
- Sample the pipeline to determine the contents, then check contents for hazardous chemicals, materials or wastes (e.g., NORM, mercury or benzene) and check external coatings such as paint and insulation for potentially hazardous wastes (e.g., lead,
asbestos, PCBs) that might require special handling procedures, disposal permits, or both.
- De-energize and isolate the pipeline from energy sources. Where a pipeline to be abandoned is connected to other pipelines (or segments) that are to remain active (live), inactive or idle, the abandoned pipeline should be isolated by physical removal,
e.g., “air-gapped.” All abandoned connections to active, inactive or idle pipelines should be permanently closed with flanges and blinds (or weld caps) per the pipeline material classification or specification. All welds and flanged
joints installed to achieve isolation should be inspected and tested per the pipeline material classification or specification. Lockout and tag out all sources of energy (e.g., pumps, rectifiers, cathodic protection systems, and valves) that are
not physically disconnected.
- Drain pipeline and dispose of the contents per the Company’s waste management plan. For pipelines with unknown or uncertain integrity, perform a negative pressure test (normally 10–15 psi for 12 hours) to verify pipeline integrity for
subsequent pigging and flushing operations.
- Pipelines with suitable integrity (or with a successful negative pressure test) should be pigged and flushed to remove as much of the remaining contents as possible. For pipelines with uncertain integrity, consider using negative pressure to pull
a pig thru the pipeline to remove fluids, which mitigates the risk of releasing contents to the environment. Recover all fluids and dispose of as per the waste management plan.
- Flush or purge the pipeline to the cleanliness level specified by national, regional and local regulations and requirements, concession terms and contractual agreements, or permit requirements. If unspecified by regulations or contractual agreement,
the project team should set the minimum cleanliness level, which for example may be specified in parts per million or “flushing until clear returns”, e.g., until there is no sheen on receiving waters in a static sheen test. The minimum
cleanliness requirement should be flushing until clear returns if no other requirements have been established. The minimum pipeline flushing volume to achieve clear returns should be 150% of the pipeline volume, but flushing efficiency is also
dependent upon achieving adequate flow velocity, so higher volumes/flowrates may be required.
- Drain the pipeline to remove, recover and dispose of flushing fluids per the waste management plan. Re-pigging the pipeline with an inert gas (typically nitrogen) is one method to remove flushing fluids.
- Prior to severing or cutting a pipeline, verify the pipeline is depressurized and free of hazardous liquids and gases, including hydrocarbons.
- Pipelines (or segments) that are abandoned in place should meet the following requirements:
- Each end of the pipeline should remain buried to a minimum depth of 3 feet or greater. Measures should be taken to ensure the pipeline ends remain stable and do not experience excessive settlement or buoyant movements during seasonal changes in soil
- Each end of the pipeline should be sealed with a welded cap, a steel plate, a skillet plate, a blind flange, a locking plug, or a grout plug.
- Each end of the pipeline should be permanently identified and then covered with appropriate materials.
- Grouting of pipelines should be required where loss of integrity (e.g. collapse of the pipe, holes, buoyancy) could potentially result in an unacceptable risk or liability to the Company (e.g. pipe greater than 10 inches in diameter under roads or
railroads, under canals, dikes, sea defense or dune crossings where the water level is higher than the surrounding land surface, or where local regulations require continuous plugging). Grouting should form a continuous plug throughout the pipeline
(or section of the pipeline) to mitigate the risk to an acceptable level.
- Pipelines should be marked with above-ground pipeline warning markers if required by applicable national, regional or local regulations and requirements, concession terms and contractual agreements, or rights-of-way or permit requirements.
- Pipelines (or segments) that are removed should meet the following requirements:
- Pipelines on the surface should be removed by severing in place and removal.
- Pipelines buried shallower than 3 feet in depth should require excavation, severing, and removal. Excavation should follow established safety procedures and may require special permits.
- Cold-cutting methods are preferred (e.g., shearing, reciprocating or circular metal saws) over hot work methods from a safety perspective. All work should follow applicable safety procedures.
- Remove all associated pipeline surface and subsurface infrastructure (including at coastal sites) unless they have future economic utility.
- Remove all pipeline minor equipment, piping, and appurtenances associated solely with pipeline operation and safety, unless they have future economic utility.
- Associated pipeline infrastructure such as buildings, roads, power lines, gravel pads, and concrete pads should be removed unless regulations, government requirements, concession or landowner/lease agreements stipulate that they remain in place.
- Document final site condition and retain all records (including, for example, “as abandoned” drawings, before-and-after photos or videos, regulatory submittals, permits and approvals, contractual records, route maps and end points of abandoned-in-place
pipelines, sampling reports, and inventory data).