This code was written with power piping in mind included to cover fuel gas and oil systems in the plant, central and district heating system, in addition to water and steam systems in power plants.This code is for making new piping. It can be used as a guide for repair / replacement.
Boiler External and Non boiler External Piping :
The code has separate requirement for boiler external and non boiler external piping. Boiler external piping is actually within the scope of Secton I of B&PV code. Section I refers to B31.1 for technical requirement. Non boiler external piping falls entirely within the scope of B 31.1. thus boiler external piping is treated as part of boiler whereas nonboiler external piping is not.
Boiler external piping is considered to start at the first weld for welded pipe, flanged face for flanged piping, or threaded joint for threaded piping outside of the boiler. It extends to the valve or valves required by Section I. Both the joint with the boiler proper piping and the valves at the end of the piping fall within the scope of boiler external piping.
Systems Covered under B 31.1:
- Boiler external piping including steam, feedwater, blowoff, and drain piping;
- Instrument, control, and sampling piping;
- Spray-type desuperheater piping for use on steam generators and reheat piping;
- Piping downstream of pressure reducing valves;
- Pressure-relief piping;
- Piping for flammable and combustible liquids;
- Piping for flammable gased, toxic gases or liquids, or non flammable non toxic gases;
- Piping for corrosive liquids and gases;
- Temporary piping systems;
- Steam trap piping;
- Pump-discharge piping; and
- District heating and steam distribution systems.