Targeting the three processes of electrochemical corrosion in buried pipelines, the anti-corrosion method for 3PE coated steel pipes starts by controlling one of these processes. Therefore, combining the anti-corrosion coating with cathodic protection is the most effective and economical solution, addressing both the symptoms and the root causes.
The lifespan of the magnesium alloy anode's coating is matched to that of the pipes, ensuring neither waste nor excessive maintenance costs due to damage during the output current process.
Different anti-corrosion methods offer varying quality and costs. The selection should be based on the specific pressure, application, environment, and type of gas transported for the 3PE coated steel pipes being maintained, considering all these factors comprehensively to determine the appropriate anti-corrosion method and cost.
When the flattened thickness is added to 50mm, cracks gradually appear along the entire length of the tube. Test results show that "hairline" cracks occur at a flattened thickness of 1 inch diameter tube. When the flattened thickness is between 6-9 inches, the sand mortar coating begins to flake off and detaches at a tube diameter of 30 inches. This is strictly prohibited during construction.
3PE coated steel pipes, when subjected to external pressure and deformation, commonly exhibit "hair-like" cracks in the mortar. However, it is extremely difficult to剥离 the mortar from the pipe wall. On a steel pipe with a diameter of DN800 and a wall thickness of 7.1mm, if a 1-meter section is cut and coated with a 11mm thick mortar layer, "hair-like" cracks can be observed when the flattening is 7-8mm.
