The major changes from the previous B149.1 edition include the following:
Updated Scope exclusions (Clause 1.2).
Updated reference publications (Clause 2).
Updated definitions (Clause 3).
Updated requirements for electrical connections and components (Clauses 4.7.3 and 4.7.4).
Updated requirements for high-altitude installations (Clause 4.22).
Updated requirements for delivery pressure (Clause 5.1).
Updated requirements for pressure regulators (Clause 5.2).
Updated requirements for overpressure protection devices (Clause 5.3).
Updated requirements for venting of pressure control devices and added requirements for venting exemptions for line pressure regulators (Clauses 5.5.2, 5.5.3, and 5.5.4).
Added new Clause 5.6 for termination of vents.
Updated requirements for material (Clauses 6.2.2, 6.2.3, and 6.2.5).
Updated requirements for size (Clauses 6.3.2 and 6.3.3).
Updated requirements for piping practices (Clause 6.8.10).
Updated requirements for joints and connections (Clauses 6.9.1 and 6.9.4).
Updated requirements for manual shut-off valves (Clause 6.18.1).
Updated requirements for gas connectors (Clauses 6.21.8 and 6.21.9).
Updated requirements for purging of gas piping systems after leak testing (Clause 6.23).
Updated requirements for compressors/pressure boosters (Clause 7.2.2).
Updated requirements for emergency generators (Clause 7.2.3).
Updated requirements for non-motive engines and turbines (Clause 7.2.4).
Updated requirements for additional requirements for gas engines and turbines in buildings (Clauses 7.2.5.1 and 7.2.5.3).
Updated requirements for direct gas-fired process air heaters (DFPAH) (Clauses 7.22.6, 7.22.7, 7.22.8, 7.22.9, 7.22.11, 7.22.12, 7.22.13, 7.22.16, 7.22.17, and 7.22.18).
Updated requirements for lighting (Clause 7.31.4).
Added requirements for operation of appliances at shows, exhibitions, or other similar events (Clause 7.35).
Updated requirements for air-supply requirements for appliances having a total input exceeding 400 000 Btu/h (120 kW) (Clauses 8.4.2, 8.4.3, and 8.4.4).
Updated requirements for air-supply dampers, louvres, and grilles (Clauses 8.5.4 and 8.5.6).
Updated requirements for cylinder storage (Clauses 9.4.3 and 9.4.4).
Updated requirements for residential fuelling appliances (RFAs) and vehicle fueling appliances (VFAs) used for natural gas without storage (Clauses 10.1.1, 10.1.2, and 10.1.3).
Added new Annex J for acceptance criteria for visual inspection of welds.
Added new Annex K for pressure regulators and overpressure protection devices.
Added new Annex L for recommended requirements for automatic safety shut-off valves and automatic vent valves installed on gas turbines having capacities greater than 12.5 MMBtu/h (3.66 MW) and inlet pressures greater than 150 PSI.
Added new Annex M requirements for the operation of appliances at shows, exhibitions, or other similar events.
Added new Annex N for generators, compressors/pressure boosters, engines, and turbines.