Yes, pipe diameters are strictly audited. For standard ordinary hazard warehouses, the branch lines carrying individual sprinkler heads are typically 25mm (1 inch) to 32mm (1.25 inches) in diameter. As branches feed into sub-mains, the pipe size increases to 50mm (2 inch), 80mm (3 inch), or 100mm (4 inch), culminating in a 150mm (6 inch) main header pipe. Sizing is governed by hydraulic calculations under NFPA 13 or IS 15105.