Some things to consider when purchasing a culvert pipe include the required class, the type of installation and the required pipe size, states Concrete-Pipe.org. The location of the culvert is also important, as culverts typically run under railways or railroads and must be able to support the weight of the load.
The class of pipe is broken into five categories, which represent the D-load capacity, notes Concrete-Pipe.org. The D-load is the supporting strength of the pipe.
The type of installation is dependent upon the soil type, compaction levels and the quality of the backfill. The location and required D-load capacity can also affect the size of the culvert and corresponding flow rates.