Gas lines greater than 2 1/2” diameter or >2psi must be purged outdoors. Large gas lines, as listed below, require purge with inert gas such as nitrogen prior to removal from service.
| Nominal Pipe Size (in.) | Length of Piping (ft.) |
| 2 1/2 | >50 |
| 3 | >30 |
| 4 | >15 |
| 6 | >10 |
| 8 or larger | Any length |
For SI unites: 1 in. = 25.4mm 1 ft. = 304.88mm
