Isolatıon Defect Detectıon
In order to protect against corrosion, facilities made of metal materials are covered with a protective coating. This coating material is usually made from plastic cored materials with very high dielectric strength. It is vital for the corrosion protection to ensure that the coating is free from any holes, pores. The service we provide covers the methods and devices (holiday detector) that are used to test whether the protective coating material is faultless (or whether there is a problem in the field installation, transport, etc.). Such applications are common in pipelines, petrochemical plants, plastic coatings, aviation industry, where protection against corrosion is required.
In additionally, it is necessary to use holiday detectors in such areas as natural gas and oil pipelines, coated tanks, building installations, enamelling, rubber coating, lining, production of coated machine parts. Corrosion is the most important problem of equipment and materials made of metal. These equipment and materials are covered with various coating materials for the purpose of protection from corrosion. A "holiday" detector is used to test whether the protection has a fault when equipment that has electrical conductivity coated or primed with a nonconductive material. The holes that can be found in the coating material are repaired by detecting "pinholes", voids, pores, worn or weakened areas. Thus, protection from corrosion is ensured.
How to Perform
The pipe made of steel is covered with a covering material with a high dielectric. The body of the pipe is tied to earth. Pulsed high voltage produced from high voltage probe of Holiday detector is applied to coating material. Holiday detector is in contact with earth with a flexible grounding cable. When any hole, pore or worn part of the coating material is encountered, the electric current will penetrate to coating at this point and it will reach to the metal body of pipe and pass from pipe to the earth. The path of the current will be completed because the grounding probe of the Holiday detector is in contact with the earth.
Thus, the current flowing out of the high voltage probe will reach the grounding probe of the holiday detector by completing the cycle through the coating material, the body of the pipe and the soil. When this current exceeds a certain value, it will be detected by holiday detector control circuit and an alarm signal will be generated. The point where the alarm signal is formed is the point at which the coating has defect. By reparation of this defect, this point is protected against corrosion. In pipelines, pipes are welded to each other at joints and junctions are insulated on site with special coating material. The proper protection against corrosion of these insulated junctions can be confirmed using holiday detectors.
The voltage on which the test is made has a special significance. This voltage should be so low as not to damage the coating material, but high enough that the faulty zones can be found completely. The efficiency and evaluation of cathodic protection are presented to you by direct survey service or practical training.