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Note: The complete set of PDFs—except for B31.4 and B31.5, which are high-resolution scans—are all original, ultra-clear vector editions with bookmarks.
Latest Editions of ASME B31 Series Volumes (as of the end of 2025):
| Code Number | Code Name | Latest Edition |
|---|---|---|
| B31.1 | Power Piping | 2024 Edition |
| B31.3 | Process Piping | 2024 Edition |
| B31.4 | Pipeline Transportation Systems for Liquids and Slurries | 2022 Edition |
| B31.5 | Refrigeration Piping and Heat Transfer Components | 2022 Edition |
| B31.8 | Gas Transmission and Distribution Piping Systems | 2023 Edition |
| B31.8S | Managing System Integrity of Gas Pipelines | 2022 Edition |
| B31.9 | Building Services Piping | 2020 Edition |
| B31.12 | Hydrogen Piping and Pipelines | 2023 Edition |
| B31J | Stress Intensification Factors & Flexibility Factors | 2023 Edition |
| B31G | Manual for Determining the Remaining Strength of Corroded Pipelines | 2023 Edition |
| B31T | Standard Toughness Requirements for Piping (mandatory reference for low-temperature applications) | 2021 Edition |
Note: B31.2 (Fuel Gas Piping) was withdrawn in 2006; B31.11 (Slurry Piping) had its final edition in 2002 and is now covered by B31.4.
The following introduces the core scope and main content of each B31 code by volume:
B31.1 Power Piping
Applies to high-temperature and high-pressure steam, feedwater, condensate, and auxiliary piping in power plants, thermal stations, industrial boilers, etc. It specifies material selection, wall thickness calculation, thermal expansion compensation, support and hanger arrangement, welding and nondestructive examination, hydrostatic testing, and in-service inspection requirements. Emphasis is placed on sustained strength and life assessment in the creep temperature range (approximately above 510 °C).
B31.3 Process Piping
The most commonly used code in “process industries” such as petroleum, chemical, pharmaceutical, and food. Fluids are categorized as high-risk (High Pressure/High Temperature/Flammable/Toxic) and normal fluids, corresponding to different design factors, examination proportions, and stress limits. It provides detailed flexibility and stress analysis clauses, cold spring methods, combinations of impact and cyclic loads, and special requirements for various non-metallic and lined piping.
B31.4 Pipeline Transportation Systems for Liquids and Slurries
Covers long-distance transmission pipelines for crude oil, refined products, chemicals, and mineral slurries. Contents include route selection and burial depth, girth weld examination proportion, coatings and cathodic protection, pump station and tank connections, surge pressure control, test mediums (water, oil, or slurry), and integrity management during operation (ILI in-line inspection, pressure test revalidation intervals).
B31.5 Refrigeration Piping and Heat Transfer Components
Applicable to commercial and industrial refrigeration systems, air-conditioning chilled water systems, and heat pumps, with fluid temperature ranges from −196 °C to 200 °C. It specifies impact testing for low-temperature brittle materials, refrigerant leakage classification (A1/A2/A3/B1/B2), special processes for brazing and copper tubing, vibration control for expansion valves and evaporator connections, and safety valve discharge capacity calculation.
B31.8 Gas Transmission and Distribution Piping Systems
Applicable to urban high-pressure, sub-high-pressure, medium-pressure, and low-pressure gas distribution networks, as well as long-distance natural gas pipelines. Design factors are set from 0.72 to 0.40 based on Location Class 1–4, requiring 100% UT/RT for girth welds or reduced factors. It provides requirements for burial depth, cased crossings under roads/railroads, cathodic protection potential criteria, leak detection intervals, and customer tie-in pressure regulation.
B31.8S Managing System Integrity of Gas Pipelines
A supplementary standard to B31.8, it outlines methods for identifying “High Consequence Areas” (HCA), threat lists (external corrosion, internal corrosion, stress corrosion cracking, third-party damage, etc.), integrity assessment methods (MFL/UT in-line inspection, Direct Assessment DA, pressure testing), and re-assessment intervals. It aligns with DOT PHMSA regulations 49 CFR 192.
B31.9 Building Services Piping
Used for HVAC, domestic hot water, compressed air, fire sprinkler, and low-pressure steam systems within commercial, residential, and public buildings. Pressure is generally ≤ 1.0 MPa and temperature ≤ 121 °C. It permits the use of threaded, copper brazed, press-fit, PEX, and other quick-connect methods. Simplified tables are provided for hanger spacing, expansion joint installation, and system hydrostatic testing, facilitating rapid selection in the construction industry.
B31.12 Hydrogen Piping and Pipelines
Addresses the transmission and station piping for pure hydrogen or hydrogen-rich gas mixtures. Due to hydrogen embrittlement risks, it sets hardness limits, maximum yield strength, and post-weld heat treatment requirements for C-Mn steel, Cr-Mo steel, stainless steel, and composite pipes. The design factor ranges from 0.72 (Class 1 location) down to 0.40 (Class 4 location), with 100% UT/RT required. It also covers hydrogen permeation leak detection, flare stack distances, and integrity re-assessment intervals.
B31J Stress Intensification Factors & Flexibility Factors
This is not a design code but provides the “i” and “k” factors required for flexibility analysis across all B31 series codes. Through extensive testing and finite element calibration, it updates the SIF (Stress Intensification Factor) and flexibility factors for fittings such as elbows, tees, miters, branch connections, and flanges, aligning stress calculation results more closely with field strain measurements. All design codes in the series reference this standard for stress verification.
B31G Manual for Determining the Remaining Strength of Corroded Pipelines
This is not a design code but a set of “field rapid corrosion assessment” tools. Through full-scale burst tests and elastoplastic finite element calibration, it provides simplified failure pressure formulas (Original/Modified B31G) and evaluation curves for localized metal loss (corrosion, mechanical gouges, etc.). This enables operators to determine whether defects require immediate pressure reduction, repair, or replacement without complex calculations. Main volumes like B31.4 and B31.8 directly reference the Remaining Strength Factor (RSF) from this manual as acceptance criteria in their integrity management clauses.
B31T Standard Toughness Requirements for Piping
This is not a standalone design code but provides a unified “low-temperature brittle fracture exemption” baseline for all main B31 volumes. It consolidates Charpy impact test temperatures, minimum absorbed energy, lateral expansion values, and exemption curves based on thickness, stress level, and material category. Calibrated through extensive fracture mechanics testing and historical failure data, it ensures sufficient toughness in low-temperature, hydrogen service, or high-strain-rate scenarios. Each volume’s “Impact Testing” section directly references B31T, making it mandatory once the service temperature falls below the exemption temperature.
Note: B31.2 (Fuel Gas Piping) was withdrawn in 2006; B31.11 (Slurry Piping) had its final edition in 2002 and is now covered by B31.4.
The following introduces the core scope and main content of each B31 code by volume:
B31.1 Power Piping
Applies to high-temperature and high-pressure steam, feedwater, condensate, and auxiliary piping in power plants, thermal stations, industrial boilers, etc. It specifies material selection, wall thickness calculation, thermal expansion compensation, support and hanger arrangement, welding and nondestructive examination, hydrostatic testing, and in-service inspection requirements. Emphasis is placed on sustained strength and life assessment in the creep temperature range (approximately above 510 °C).
B31.3 Process Piping
The most commonly used code in “process industries” such as petroleum, chemical, pharmaceutical, and food. Fluids are categorized as high-risk (High Pressure/High Temperature/Flammable/Toxic) and normal fluids, corresponding to different design factors, examination proportions, and stress limits. It provides detailed flexibility and stress analysis clauses, cold spring methods, combinations of impact and cyclic loads, and special requirements for various non-metallic and lined piping.
B31.4 Pipeline Transportation Systems for Liquids and Slurries
Covers long-distance transmission pipelines for crude oil, refined products, chemicals, and mineral slurries. Contents include route selection and burial depth, girth weld examination proportion, coatings and cathodic protection, pump station and tank connections, surge pressure control, test mediums (water, oil, or slurry), and integrity management during operation (ILI in-line inspection, pressure test revalidation intervals).
B31.5 Refrigeration Piping and Heat Transfer Components
Applicable to commercial and industrial refrigeration systems, air-conditioning chilled water systems, and heat pumps, with fluid temperature ranges from −196 °C to 200 °C. It specifies impact testing for low-temperature brittle materials, refrigerant leakage classification (A1/A2/A3/B1/B2), special processes for brazing and copper tubing, vibration control for expansion valves and evaporator connections, and safety valve discharge capacity calculation.
B31.8 Gas Transmission and Distribution Piping Systems
Applicable to urban high-pressure, sub-high-pressure, medium-pressure, and low-pressure gas distribution networks, as well as long-distance natural gas pipelines. Design factors are set from 0.72 to 0.40 based on Location Class 1–4, requiring 100% UT/RT for girth welds or reduced factors. It provides requirements for burial depth, cased crossings under roads/railroads, cathodic protection potential criteria, leak detection intervals, and customer tie-in pressure regulation.
B31.8S Managing System Integrity of Gas Pipelines
A supplementary standard to B31.8, it outlines methods for identifying “High Consequence Areas” (HCA), threat lists (external corrosion, internal corrosion, stress corrosion cracking, third-party damage, etc.), integrity assessment methods (MFL/UT in-line inspection, Direct Assessment DA, pressure testing), and re-assessment intervals. It aligns with DOT PHMSA regulations 49 CFR 192.
B31.9 Building Services Piping
Used for HVAC, domestic hot water, compressed air, fire sprinkler, and low-pressure steam systems within commercial, residential, and public buildings. Pressure is generally ≤ 1.0 MPa and temperature ≤ 121 °C. It permits the use of threaded, copper brazed, press-fit, PEX, and other quick-connect methods. Simplified tables are provided for hanger spacing, expansion joint installation, and system hydrostatic testing, facilitating rapid selection in the construction industry.
B31.12 Hydrogen Piping and Pipelines
Addresses the transmission and station piping for pure hydrogen or hydrogen-rich gas mixtures. Due to hydrogen embrittlement risks, it sets hardness limits, maximum yield strength, and post-weld heat treatment requirements for C-Mn steel, Cr-Mo steel, stainless steel, and composite pipes. The design factor ranges from 0.72 (Class 1 location) down to 0.40 (Class 4 location), with 100% UT/RT required. It also covers hydrogen permeation leak detection, flare stack distances, and integrity re-assessment intervals.
B31J Stress Intensification Factors & Flexibility Factors
This is not a design code but provides the “i” and “k” factors required for flexibility analysis across all B31 series codes. Through extensive testing and finite element calibration, it updates the SIF (Stress Intensification Factor) and flexibility factors for fittings such as elbows, tees, miters, branch connections, and flanges, aligning stress calculation results more closely with field strain measurements. All design codes in the series reference this standard for stress verification.
B31G Manual for Determining the Remaining Strength of Corroded Pipelines
This is not a design code but a set of “field rapid corrosion assessment” tools. Through full-scale burst tests and elastoplastic finite element calibration, it provides simplified failure pressure formulas (Original/Modified B31G) and evaluation curves for localized metal loss (corrosion, mechanical gouges, etc.). This enables operators to determine whether defects require immediate pressure reduction, repair, or replacement without complex calculations. Main volumes like B31.4 and B31.8 directly reference the Remaining Strength Factor (RSF) from this manual as acceptance criteria in their integrity management clauses.
B31T Standard Toughness Requirements for Piping
This is not a standalone design code but provides a unified “low-temperature brittle fracture exemption” baseline for all main B31 volumes. It consolidates Charpy impact test temperatures, minimum absorbed energy, lateral expansion values, and exemption curves based on thickness, stress level, and material category. Calibrated through extensive fracture mechanics testing and historical failure data, it ensures sufficient toughness in low-temperature, hydrogen service, or high-strain-rate scenarios. Each volume’s “Impact Testing” section directly references B31T, making it mandatory once the service temperature falls below the exemption temperature.
