"At the time we had evaluated two contractors/applicators of this technique and the IPS team was chosen as clearly the better.
Senior Materials and Corrosion Engineer
When it comes to ensuring the coating will bond properly to the pipe wall, surface preparation is the most critical factor. The in-situ coating process provides two different and distinct methods of cleaning the pipe wall; the two methods are abrasive blasting and chemical cleaning. Each method is adequate for obtaining the proper surface preparation. The abrasive blasting procedure will produce a NACE 1, white metal surface, and is typically utilized on newly installed pipelines. Chemical cleaning will produce a minimum of a NACE 2, near-white metal surface and is used for rehabilitation of existing pipelines. The coating is designed to adhere effectively to either surface, however, over the years; the bulk of the work has been credited to chemical cleaning.
Cleaning by Abrasive Blasting to New Pipelines.
Abrasive blasting is an internal cleaning method that injects hard cleaning particles into a gaseous medium, normally nitrogen or dry compressed air. The gas or air is introduced into the pipeline in a manner to create a turbulent critical flow rate at an extremely high velocity, which causes the abrasive cleaning particles to impact the internal surface of the pipe wall. The impact of the particles, removes oxides and hard scale deposits, producing a NACE 1 finish.
Depending on the pipeline characteristics, such as, diameter, bends and other geometric considerations, a single setup can clean approximately 1/3 of the diameter, expressed in miles. As an example: A 12” pipeline can be blasted in approximately 4 mile sections in one setup…whereas a 12″ x 8 mile pipeline would be completed in 2 sections.
Chemical Cleaning for Rehabilitation.
Internal Pipeline Solutions (IPS) utilizes a multi-stage system that consists of both mechanical and chemical cleaning. The first phase consists of detergent based batches to remove residual oils left in the pipeline. The next phase introduces brush pigs to remove heavy scale from the line. These runs are followed by batches of inhibited Acid formulated to remove all remaining scale and oxidation on the pipe wall. This process of mechanical and chemical cleaning is tightly monitored through samples collected after each run and will produce a near white metal finish on the pipe wall. Through analysis of the samples, visual inspections of pigs, and when possible visual inspection of the pipeline itself, I.P.S. will determine when the proper level of cleanliness has been achieved for coating. The final phase of cleaning involves passivating the surface of the pipe wall, adjusting the pH and chloride levels with inhibited water runs, and finally solvent runs to dry the pipeline. I.P.S. works closely with our clients before, during, and after the project to determine, on an individual basis, the best disposal options of all effluent generated during the process.
Coating is mixed and loaded between specially designed pigs. The mixing and loading process is closely monitored to ensure the manufacture’s specifications are adhered to. Once the coating is loaded in the pipeline, the batch is launched. During the coating run, the drive and back pressures are tightly regulated to ensure the speed of the batch is consistent throughout the run. Maintaining a consistent speed ensures the coating is applied uniformly. A typical coating run will apply 1.5-3.0 mils. The coating is applied over 3-4 days, with a final thickness between 8-10 mils. After each coating run, dry air is blown through the pipeline to aid in drying and the removal of solvents. Theoretical coverage is calculated based on gallons loaded and gallons unloaded and followed by dry mil measurements after the final coat is applied. This process has proven to be extremely effective in completely and uniformly covering the entire length of pipeline with a continuous epoxy barrier.