1.1 Scope 1. 1.1 This standard covers gas utilization equipment in boilers having inputs over 400,000 Btu per hour per combustion chamber except water-tube boilers having outputs of 10,000 pounds of steam per hour (approximately 12,500,000 Btu per hour input) or more. 1. 1.2 This standard does not apply to gas utilization equipment in boilers: (a) covered by American National Standard Installation of Gas Appliances and Gas Piping, Z21.30-1964, (b) covered