Exhaust Pipe Joint Welding Diagram - Acceptable vs. Preferred Transitions

This document is a simple hand-drawn schematic illustrating correct and incorrect methods of joining two exhaust pipes of different diameters by welding. A legend at the top indicates that red lines represent welds. Three joint configurations are shown relative to the direction of exhaust gas flow (labeled 'EXHUAST GAS FLOW' with an arrow). The first, labeled 'ACCEPTABLE,' shows the smaller pipe inserted into the larger pipe so gas flows from the smaller pipe into the larger one. The second, labeled 'UNACCEPTABLE,' shows the larger pipe positioned so gas flow encounters an abrupt internal step (the smaller pipe slipped inside against the flow direction). The third, labeled 'PREFERRED,' shows the smaller pipe spread (or a reducer smoothly connected at each end) to create a smooth taper into the larger pipe; a note explains that a smooth transition presents no problem no matter which way the gas flows, indicated by a double-headed arrow. A reader can learn general best practice for exhaust pipe joint orientation and welding: avoid abrupt steps facing the gas flow, and prefer a smoothly tapered transition. The diagram is generic and contains no vehicle-specific years, models, part numbers, or dimensions.