Tiruppur (India) and Nagapattinam (India) are 274 km (170 mi) apart in a straight line. The way we suggest is by train and bus, via Coimbatore, Thanjavur and Velankanni: ~7h 40m door to door with 3 changes. No flight is needed.
Step by step
Train from Tiruppur to Coimbatore: about 45m, 44 km
Train from Coimbatore to Thanjavur: ~3h 30m, 239 km
Bus from Thanjavur to Velankanni: about 2h 20m, 77 km
Bus from Velankanni to Nagapattinam: about 20m, 9 km
Every route we know
Train + Bus, via Coimbatore, Thanjavur and Velankanni: ~7h 40m, 3 changes
Train + Bus, via Bengaluru and Velankanni: ~12h 50m, 2 changes
Times are rough door-to-door times, with time to change included. A "~" marks a rough time worked out from the distance. We don't have timetables, and fares are rough estimates, not quotes: check Google Maps or the operator before you travel.