A fire protection system can include one or more pipes coupled with a fluid source, a pipe fitting coupled with the one or more pipes downstream of the fluid source, and at least one sprinkler coupled with the one or more pipes and the pipe fitting. The pipe fitting can include a wall defining an opening, the wall having an outer diameter, a first wall thickness at the opening, and a second wall thickness inward from the opening, the second wall thickness greater than the first wall thickness. The at least one sprinkler can be coupled with the one or more pipes and the pipe fitting to receive fluid from the fluid source through the one or more pipes and the pipe fitting.