Non-metallic coating corrosion monitoring system outside the pipeline corrosion failure of anti-corrosion layer is mainly manifested in the aspects of physical corrosion failure

Corrosion monitoring system for nonmetal anticorrosive coating corrosion failure with material aging, biodegradable, environmental stress cracking of chemical corrosion failure phenomenon, but the main body of physical corrosion failure. Anticorrosive coating with luo injury types of common damage, water absorption, cracking, delamination, stripping, grounding through physical corrosion morphology and invasive corrosion, etc. Outside the pipeline anticorrosion layer physical corrosion failure is mainly manifested in four aspects.

(1) the external force damage damage pipeline anticorrosion layer and hard to avoid in the construction process of anticorrosion layer knock against, scratches and other mechanical damage. Different construction conditions, the performance requirements of the coating is also different. Running environment, the pollution of the soil chemistry, biological degradation, the stress, the stones in the soil and soil load of luo and penetrate and other physical effects of plant roots, and the change in temperature of pipeline operation, etc., can be anticorrosive coating damage.

(2) the penetration of corrosive medium Because organic coating itself with many inherent defects, such as micro cracks exist inside coating substrate molecule cavity, and micro bubbles, packing and interface between resin pore are corrosive medium in the anti-corrosion layer of penetrating way. Osmotic medium accumulated to a certain degree, and the temperature change caused by the environment, such as heat bilges cold shrink, leads to the coating produce sudden physical damage, formation of physical corrosion failure.

(3) corrosion for quality is not good In long distance pipeline, the single pole after welding on the joint section of anticorrosion to ensure the integrity of the pipeline corrosion protection layer, which is referred to as a anticorrosive fill the mouth. Repairing is conducted in the construction site, if material inappropriate or improper construction technology, can cause a seal for lax, bonding defects such as bad. Outside our country long-distance pipeline corrosion investigation showed that the joint failure caused by the poor quality of anti-corrosion layer is one of the main causes of pipeline corrosion accidents.

(4) stress corrosion damage of stress corrosion is refers to the metal box alloy under the synergy of corrosion medium and tensile stress caused by the damage phenomenon. Result in clothing city physical corrosion failure stress mainly include soil stress, such as forming residual stress and swelling stress. Stress corrosion is characterized by the formation of corrosion, mechanical crack, crack once formed, the corrosive medium permeability to expand rapidly, lead to external anti-corrosion layer falls off, promotes the extension for defects, dryness or even fall off.