- The design operating gas pressure is greater than 2 psig (13.79 kPa).
- The piping being purged contains one or more sections of pipe or tubing meeting the size and length criteria of Table 406.7.1.1.
Where existing gas piping is opened, the section that is opened shall be isolated from the gas supply and the line pressure vented in accordance with Section 406.7.1.3. Where gas piping meeting the criteria of Table 406.7.1.1 is removed from service, the residual fuel gas in the piping shall be displaced with an inert gas.
SIZE AND LENGTH OF PIPING
|NOMINAL PIPE SIZE |
|LENGTH OF PIPING |
|≥ 21/2 < 3||> 50|
|≥ 3 < 4||> 30|
|≥ 4 < 6||> 15|
|≥ 6 < 8||> 10|
|≥ 8||Any length|
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm.
- CSST EHD size of 62 is equivalent to nominal 2-inch pipe or tubing size.
The open end of a piping system being pressure vented or purged shall discharge directly to an outdoor location. Purging operations shall comply with all of the following requirements:
- The point of discharge shall be controlled with a shutoff valve.
- The point of discharge shall be located not less than 10 feet (3048 mm) from sources of ignition, not less than 10 feet (3048 mm) from building openings and not less than 25 feet (7620 mm) from mechanical air intake openings.
- During discharge, the open point of discharge shall be continuously attended and monitored with a combustible gas indicator that complies with Section 406.7.1.4.
- Purging operations introducing fuel gas shall be stopped when 90 percent fuel gas by volume is detected within the pipe.
- Persons not involved in the purging operations shall be evacuated from all areas within 10 feet (3048 mm) of the point of discharge.
The purging of piping systems shall be in accordance with the provisions of Section 406.7.2.1 where the piping system meets both of the following:
- The design operating gas pressure is 2 psig (13.79 kPa) or less.
- The piping being purged is constructed entirely from pipe or tubing not meeting the size and length criteria of Table 406.7.1.1.
The piping system shall be purged in accordance with one or more of the following:
- The piping shall be purged with fuel gas and shall discharge to the outdoors.
- The piping shall be purged with fuel gas and shall discharge to the indoors or outdoors through an appliance burner not located in a combustion chamber. Such burner shall be provided with a continuous source of ignition.
- The piping shall be purged with fuel gas and shall discharge to the indoors or outdoors through a burner that has a continuous source of ignition and that is designed for such purpose.
- The piping shall be purged with fuel gas that is discharged to the indoors or outdoors, and the point of discharge shall be monitored with a listed combustible gas detector in accordance with Section 406.7.2.2. Purging shall be stopped when fuel gas is detected.
- The piping shall be purged by the gas supplier in accordance with written procedures.