How should metal pipes of dissimilar metals be joined to prevent electric current passage?

Joining dissimilar metal pipes requires methods that prevent galvanic corrosion and electric current passage. Using approved insulation is the correct approach because it provides a barrier that prevents electrical conductivity between the metals. This insulation can come in various forms, such as coatings or mechanical insulation, which help to protect the interface of the two dissimilar metals from direct contact, thus reducing the risk of electric current passage and galvanic corrosion.

This method is essential in maintaining the integrity and safety of piping systems, especially where different metals might be used that can create electrochemical reactions in the presence of an electrolyte. By employing insulation, you effectively mitigate the potential for damage and maintain the longevity of the installation.

In contrast, directly connecting the metals, using an appropriate coupling, or welding them together would not provide the necessary separation to prevent electric current from flowing between the two dissimilar materials. Such connections could lead to accelerated corrosion and potentially compromising the system's reliability and safety.