Natural gas pipelines are externally coated to prevent moisture from coming into direct contact with the steel and causing corrosion.
This process typically is completed before the pipeline is delivered to the construction site. All coated pipelines are delivered with uncoated areas three to six inches from each end to prevent the coating from interfering with the welding process.
Once the welds are completed, a coating crew coats the remaining portion of the pipeline before it is lowered into the ditch.
Prior to lowering the pipe into the trench, the coating of the entire pipeline is inspected to ensure it is free of defects.
Other steps in the constructions process:
- Clearing and grading
- Pipe bending and Welding
- Depositing the pipeline and Backfilling