Spiral steel pipe thermal insulation method of inhibiting them from the start of a process, such as anti-corrosion coating on the pipe wall plus, loop resistance can be increased, reducing the corrosion current; external DC power supply, so that the soil pipe causing negative potential, the formation of cathodic protection can eliminate anode potential difference, a fundamental process for stopping the anode and cathode. anticorrosion coating rule table, cathodic protection of the rule of law, but once the anti-corrosion coating is damaged, exposed iron parts will accelerate localized corrosion. therefore anti-corrosion coating and cathodic protection is the table of the combined method of treating both, economical and effective. U.S. and other countries have been clearly defined, using the anti-corrosion coating cathodic protection must be used at the same time.
But for the city gas system, due to intensive underground pipe network, external power cathodic protection to other pipeline interference, can cause its own benefit, his family situation of the victims, while using a negative potential than the metal pipe spiral pipe connected with sacrificial anode law does not appear to protect such cases, therefore, the city's gas mains gas should be used to anticorrosion coating combined with sacrificial anode corrosion methods for other non-main pipeline pressure is low, then the anti-corrosion coating method generally used directly .
Buried gas pipeline insulation currently used mainly in the outer layer PE anti-corrosion coating composite structure, epoxy powder, coal tar enamel, coal tar epoxy and PE tape and other five categories. Layer PE composite structure, anti-corrosion epoxy powder coating performance, and therefore the United States and Europe the main buried pipeline anticorrosion coating in our country, from the useful life, maintenance costs and other comprehensive economic factors to consider, generally preferred anti-corrosion coating layer PE composite structure.
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