In Situ Coating
Definition - What does In Situ Coating mean?
In situ coating is a coating method which provides a uniform homogeneous coating throughout the pipeline, including all field joints (welds) and bends.
In situ coating applications are extremely effective and can be used on all types of oil and gas lines, potable water lines, freshwater injection lines, commingled water injection lines, as well as in aviation fuel lines.
The in situ coating process protects pipelines from corrosion, erosion and heat while friction coefficients are improved, resulting in significant gains in throughput and horsepower savings of up to 60% from a typically scaled pipeline.
Corrosionpedia explains In Situ Coating
In situ coating prevents corrosion from taking place within a pipeline at a fraction of the cost of pipeline replacement. Some of the benefits to in situ pipeline coating (internal pipeline coating) include:
- Friction protection
- Corrosion protection
- Paraffin retardation
- Erosion protection
- Joint protection
The in situ coating process drastically reduces the number of dig-ups required, which lessens environmental impact, appeases landowners and reduces risk involved with river and/or road crossings. Pigging programs and costly inhibitor programs can be drastically reduced or eliminated once the pipeline is internally coated.
With in situ coating, the epoxy coating is selected for its capabilities and service in its specific pipeline operation. The coating is a combination of base and hardener that is prepared and mixed before loading into two modified polyurethane scrapers. The desired film thickness is achieved by ensuring a predetermined drive pressure and velocity throughout the pipeline.
The coating is applied to the inside of the pipeline wall by means of extrusion. The coating application specification calls for a minimum of three coating runs to reach the desired dry film thickness (DFT). Between each coating run, dry particulate-free air is pumped through the pipeline to ensure solvent evaporation. The drying period between the coating batches is about 16 hours. The inspection of the dry film thickness is taken at predetermined points along the pipeline.
The coating system prevents corrosion in hydrocarbon, gas, and water injection steel pipelines, and works with oil, gas, water, petroleum products, food and chemical products. It has the ability to cover pits and channel corrosion, and covers all lateral and girth welds.