When conducting a Wenner 4 pin test, the position of the pins relative to the pipe should be:

In a Wenner 4-pin test, the method is designed to measure the soil resistivity for corrosion potential analysis, particularly around buried metallic structures like pipes. The arrangement of the testing pins is crucial for obtaining accurate measurements.

Placing the pins perpendicular to the pipe allows for an effective measurement of the resistivity in the soil surrounding the structure. This geometry ensures that the electrical current flows uniformly between the outer pairs of pins and that the potential difference is accurately captured between the inner pairs. By having the pins perpendicular, it helps to minimize the influence of any non-uniformity in the soil or nearby structures, leading to more reliable data.

Other arrangements, such as parallel, diagonal, or at an angle, can introduce variability and inconsistencies in the measurements due to the geometry of the current flow and the potential field around the test setup. Thus, organizing the pins perpendicularly to the pipe maintains the integrity and accuracy of the resistivity measurement.