Buried pipeline must have a tightly packed anti-corrosion layer, pipe should be applied to important power protection - protection impressed current or sacrificial anode protection. But buried pipeline coating damage occurs due to construction of the building, stripping, from other reasons, can cause pipe corrosion, perforation, leakage, resulting in shortened life of the pipeline. In order to ensure that the pipeline from beginning to end are in good running condition, in addition to routine testing for general pipe outside. Should also control the pipeline to potential, soil resistivity, coating insulation resistance, DC current, AC current, overcast insurance current, stray current drainage and other comprehensive tests to ensure the effectiveness of catholic protection system .
Management to potential measurement
A . SP measurements
By measuring the natural potential of the pipeline can be found in pipeline AC, DC stray current interference in the frequency and size. Take the appropriate drainage measures to prevent pipe corrosion caused by stray current.
Paul Yin potential measurement
B. Cathodic protection potential measurements
In order to pipeline corrosion process to stop or minimize the often negative security pass to the current pipeline, the pipeline at this time should ensure that potential negative security (to eliminate IR drop) in an appropriate range (usually-0.85v ~-1.5v). Yin can not guarantee protection from the potential role of the small, outer coating over the General Assembly created the peeling off and so on. Billiton detected in the use of advanced scientific instruments division and combined with years of practical experience, working for the safe operation of your pipeline escort.
1, the surface reference measurement
The reference electrode placed on the surface in a vertical pipe surface, so that reference electrode (Cu/Cuso4) and full contact with moist soil.
2, near the reference measurement
In the pipe above the test pile dug within a meter of a reference electrode placed in the test pit, the reference electrode placed at the 3 ~ 5cm away from the wall, through a dedicated voltage meter to measure the potential, can effectively eliminate the IR drop on the measurement results.
3, the instantaneous power measurement
The way is connected to all ground and pipeline protection, sacrificial anode Disconnect all. Point in the test should not have stray current interference, the use of fast response measurement of automatic recorder.
4, the test pieces measuring point
In the same test material and the pipeline processing of a specimen, specimen connected pipe and make it fully polarized, only the sample measurement and the pipeline can be disconnected in order to avoid cutting off the main pipeline protection current and other electrical coupling trouble. This method can effectively eliminate the impact of IR drop.
C. Sacrificial Anode Ground Resistance Testing
Sacrificial anode ground resistance testing can be divided into two kinds: sacrificial anode stick and anode bed testing.
If the Sacrificial anode ground resistance exaggerate, that will lead to pipeline’s partial cannot be protected, not only the cathode protection system’s abnormal working, if seriously, the inner and outer of the pipeline will be corrosive. And if the anode bed ground resistance exaggerate, the whole cathode protection system cannot work well so that the pipeline will be corrosive seriously.
The Detection Department of ZhongTuo Pipeline Cleaning & Repairing Co.,Ltd introduced the advanced testing technology, this can detect the anode resistance of the pipeline sacrificial anode puncheon and anode bed, then resolve whether they are in good working condition.
D. Continuous & Chaotic Eddy Current Testing
Eddy current usually comes from the nearby electrified railway, electricity plant, cathode protection system, high-pressure ground device and other objects. After going into the pipeline, the current will flow in it and cause electrolytic corrosion to the place where it flow out. The corrosion depends on the magnitude of the current and density, geographical position and thickness of layer.
The Detection Department of ZhongTuo Pipeline Cleaning & Repairing Co.,Ltd introduced the eddy current tester. It can be widely used in real-time observation of the eddy current existing in the underground oil, gas and water pipeline. After the calculation of the data, the maximum, the minimum and the average can be mastered, and then the eddy current changing chart can be drawn, meanwhile we can put forward the reliable scientific principle for mastering the eddy current’s distribution and adopting the appropriate protective measure. So the detection of the eddy current is necessary for pipeline design and cathode protection’s operation, meanwhileit is also the necessary detection means for object technology measurement, assessment of the protection effect and supervision of working condition.
E. Insulating Flange Insulation Test
The insulation of insulated flange directly affects non-electrochemical corrosion protection section of the pipeline. Flange insulation if the insulation is not good, overcast Paul currents into the pipeline directly through the insulation of non-protected section of the flange, resulting in non-protected section of the electrochemical corrosion of pipes, and could easily lead to under-protected section of the pipeline protection. In order to ensure good insulation insulating flange, extend service life of pipes must be installed or has not yet been buried insulating flange for insulation testing.
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