PTTEP_PTO-A to PTO-D to NTM-A Project
PIPE-TO-SOIL POTENTIAL TEST
The conclusion of the pipelines is more negative than -700mVCSE, which makes it easier to polarize the pipes to reach the minimum goal of -850mVCSE. The consistent good native potential values indicate that the pipes’ coating is in good condition.
The ON potentials observed at each TP, indicate values more negative than -850mVCSE, which one of the basic criteria of CP as per NACE SP 0169-2013.
The potentials measured of the all the anodes were consistent with the theoretical Magnesium anode potential with respect to CSE. It also indicates that all the anodes are safely installed and no cables were broken during installation.
The inspection shows that at each TP, the CP current per anode is sufficient to protect the both the pipelines at that location. One anode at each TP has been connected to cathodically protect the two pipelines. The extra anodes can be used over the period of the pipeline as the pipes’ coating or soil conditions change.
DCVG TEST
The test report shows the ON/OFF potential from the temporary ICCP system set up for DCVG inspection test. During this test, there was no indication of coating breakdown on the two 9.346 km pipelines. A variation in potential signal at each test post is due to the change in soil resistivity.
PCR TEST
The insulation joint is used to separate between pipes on the ground and underground. The PCR is installed at the insulation joint. In this pipeline project 6 PCR (1 PCR/ IJ) were installed. The results, DC current between pipeline connections are almost 0 mA-DC and AC-RMS current between pipeline connection points is more than 0 mA-AC. This would prevent CP current to be passed on to the above ground pipes and drain AC current to be passed above ground pipes.
Description
The cathodic protection current was determined by assuming 0.25% coating breakdown of the both the 8” pipelines 8.806 km in a soil resistivity 3000 Ohm-cm. The conservative calculations showed that in order to meet the CP current a total of 69 magnesium anodes will be needed. But as an extra precaution, 69 anodes(3 anodes/ TP) were decided to be installed. In the pipeline PTO-D to NTM-B at Kp.0+005, it was found that the CP current of the pipe was leaking to casing. The 3 magnesium anodes (3 anodes/ TP) were installed to prevent Casing to solve the problem.
Details
- OWNER: PTT EXPLORATION AND PRODUCTION PUBLIC CO.,LTD.
- CONTRACTOR: TESCO ENGINEERS CO.,LTD.
- LOCATION: Sukhothai, Thailand.
Project skills
- Installation complete
- Presentation