The design consists of the features of shape and configuration of the Pipe Fitting shown in solid lines in the drawings. In the drawings:Figure 1 is a front perspective view of the Pipe Fitting:Figure 2 is a rear perspective view thereof;Figure 3 is a left end elevational view thereof;Figure 4 is a right end elevational view thereof;Figure 5 is a left side elevational view thereof, with the right side elevational view being a mirror image thereof;Figure 6 is a top plan view thereof;Figure 7 is a bottom plan view thereof; andFigure 8 is a cross sectional view thereof along line 8-8 of Figure 1.