Installation and test of PM-5U, PM-10U, PU-20U anodes

Magnesium anode installation is a reliable method to provide electrochemical protection for the steel constructions against corrosion. These devices work well with 50 Om/m resistance soil. Their electrical capacity (in theory) is about 2200 A/h. Let's look at the design of popular PM-5U, PM-10U, PU-20U anodes, their installation and test. Construction elements:
  • anode made from a magnesium alloy with a steel contact core;
  • package - a cotton bag with a powered activator;
  • a three-meter connecting cable P-274 (or any other to Client's needs) which is outside.


The device is placed in an activator, rather than in soil to provide protection. This gives high protective potential, which, in its turn, prevents the development of low-solubility films on anode surface, evenly spreads the activator over the surface and decreases the resistance between soil and magnesium anode. Prior M-5U, PM-10U, PU-20U anode installation, it is necessary to calculate the number of anodes to be used per one unit of pipe range. This number depends on pipe diameter and environment aggressiveness and is calculated when the system is designed. On average, one PM-10U protects a pipeline part of up to 1 km. Right before the installation, the packaging is removed. Steel wire is attached to a loop of a cotton bag where the device is supplied in, then this steel wire helps to carefully place the device in a drilled well. Then the anode is covered with soil, which is compacted, and the wire is taken off. More soil is added into the well, and the installed place is compacted as well. If the soil is dry, then 2 - 3 pails of water are poured into the well. Protection system is installed at about 5 meters from a protected pipeline. Anodes can be installed in an isolated manner or in a group manner with 5 - 15 anodes in a group.

How to test the installed anodes PM?

It is necessary to follow this procedure to thoroughly test cathodic electrochemical protection:
  • remove a plate;
  • connect terminals of the tested device;
  • measure the voltage;
  • re-install a plate.
The value should be within 0.6 to 1.5 V. If this value is higher than 3 V, then the connection and one of the anodes should be cut off, if it is less than 0.6 V, then the anode does not work. The test should be carried out once per three months.