This webinar compiles information regarding known factors, components, and conditions associated with internal corrosion of natural gas metal pipe. It supplies context to the topic and background information for natural gas and RNG. Corrosion mechanisms and combined effects are described. It is clear that water is the most important factor for pipeline corrosion; corrosion mechanisms will not occur without the presence of water. This is true both of natural gas and RNG systems. Other major components contribute to corrosion in the presence of water, individually and in combinations, and the process is complicated and variable. Unless the pipeline system is completely devoid of water, there is no circumstance, with natural gas or RNG, which assures a corrosion-free environment. All constituents which contribute to a corrosive environment must be controlled as best possible, at all times, and well-constructed corrosion management programs should monitor internal pipe conditions.