Interior pipeline coating process

An in situ method of repairing an extending subsurfaced pipeline having a corroded interior surface and firs and second opposite ends, the method comprising the steps of:

• cleaning and treating the interior surface to prepare it for application thereto of a corrosion protective and reinforcing coating;
• providing a first quantity of corrosion protective and reinforcing coating material at least sufficient to entirely coat the cleaned interior surface with a first protective and reinforcing layer having a predetermined thickness and to fill corrosion depressions in the interior surface, the protective and reinforcing coating material being a 100% solid, high viscosity, solvent-free epoxy coating material;
• providing leading and trailing extruder pig members, the trailing pig members having first and second spaced apart disc portions thereon;
• positioning the leading and trailing extruder pig members in a spaced apart relationship in the extended pipeline;
• placing the quantity of corrosion protective and reinforcing coating material between the spaced apart leading and trailing extruder pig members;
• utilizing pressurized air to propel the spaced apart leading and trailing extruder pig members, and the corrosion protective and reinforcing coating material positioned therebetween, through the pipeline, from the first end thereof to the second end thereof;
• causing the coating material between the pigs to alternatively shift between axial and circumferential flow through offset passages in the trailing extruder pig member to mix the coating material, prior to discharge of the coating material past the trailing extruder pig member;
• continuously displacing the coating material outwardly past the trailing pig member and onto the interior surface to extrudingly form the first protective and reinforcing layer thereon and fill the corrosion depressions;
• flowing dehydrated air through the extended pipeline to cure the first layer of the corrosion protective and reinforcing coating material;
• and
• passing the leading and trailing pig members, and at least one additional quantity of the corrosion protective and reinforcing coating material through the pipeline again, to form on the first protective and reinforcing layer at least one additional protective and reinforcing layer defining therewith a multi-layer coating of sufficient thickness to provide a substantial measure of internal structural reinforcement to the extended subsurfaced pipeline through its length.