It would depend on the fluid and what is being eroded.
Typically during channel stability (in the case of erosion) the shear stress would be evaluated based on the velocity, surface cover, type of soil, liner, etc. and compared to the published data for the soil type. Based on this information, you would be able to predict the conditions at which erosion would occur.
You have said that you're working on a gas production project. Are you speaking of the gas being the fluid? or would you be speaking about rainwater runoff? Either could be erosive depending on the application (i.e within a channel, on a slope or even in an excavation) and soil type.
Pressure pipe flow and/or gravity pipe flow could also be erosive.
If you could provide some additional details it would be helpful for the forum to aid in answering your question.
