ASME code: ASME code for pressure piping and scope of code (B31.1)

ASME code for pressure piping

These are the below mention code presently the following sections of ASME B31, Code for Pressure Piping are published.

ASME B31.1 Power Piping
USAS B31.2 Fuel Gas Piping
ASME B31.3 Process Piping
ASME B31.4 Liquid Transportation Systems for Hydrocarbons, Liquid Petroleum Gas, Anhydrous Ammonia, and Alcohol
ASME B31.5 Refrigeration Piping
ASME B31.8 Gas Transmission and Distribution Piping Systems
ASME B31.9 Building Services Piping
ASME B31.11 Slurry Transportation Piping Systems


ASME B31.1, Power Piping Code, prescribes requirements for the design, material, fabrication, erection, test, and inspection of power and auxiliary service piping systems for electric generation stations, industrial and institutional plants, central and district heating plants, and district heating systems. It does not apply to piping systems covered by other sections of the Code for Pressure Piping, and other piping which is specifically excluded from the scope of this code

As explained earlier, the BEP is required to meet administrative jurisdictional requirements of ASME Section I; however, pipe connections meeting all other requirements of ASME B31.1 but not exceeding nominal pipe size (NPS) 1⁄2 may be welded to boiler external pipe or boiler headers without inspection and stamping required by ASME Section I.

Nonboiler external piping is defined as all the piping covered by ASME B31.1 with the exception of BEP. The nonboiler external piping must be constructed in accordance with the requirements of this code.

In addition to the piping systems covered by other sections of ASME B31, Pressure Piping Code, ASME B31.1 does not cover the following:

  • Economizers, heaters, pressure vessels, and components covered by the ASME Boiler and Pressure Vessel Code (except the connecting piping not covered by the ASME Boiler and Pressure Vessel Code shall meet the requirements of ASME B31.1)
  • Building heating and distribution steam piping designed for 15 psig (100 kPa gauge) or less, or hot-water heating systems  piping designed for 30 psig (200 kPa gauge) or less
  • Piping for roof and floor drains, plumbing, sewers, and sprinkler and other fire-protection systems
  • Piping for hydraulic or pneumatic tools and their components downstream of the first stop valve off  the system distribution header
  • Piping for marine or other installations under federal control
  • Piping covered by other sections of ASME B31 and ASME Section III
  • Fuel gas piping within the scope of ANSI Z 223.1, National Fuel Gas Code
  • Pulverized fuel piping within the scope of NFPA

The requirements of this code apply to central and district heating systems for distribution of steam and hot water away from the plants whether underground or elsewhere, and geothermal steam and hot water piping both to and from wellheads.

The construction of fuel gas or fuel oil piping brought to plant site from a distribution system inside the plant property line is governed by the requirements of ASME B31.1 when the meter assembly is located outside the plant property line. In cases where the meter assembly is located within the plant property line, the requirements of this code shall apply to the fuel gas and fuel oil piping down¬stream from the outlet of the meter assembly

This code also applies to gas and oil systems piping other than tha . It covers air systems, hydraulic fluid systems piping, and the steam-jet cooling systems piping which are part of the power plant cycle. In addition, building services within the scope of ASME B31.9 but outside the limits of Paragraph 900.1.2 of B31.9 are required to be designed in accordance with ASME B31.1

 Scope of ASME B31.2 Fuel Gas piping and B31.3 Process piping check here

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