ASME B31.3 documents contain about detailed information regarding materials, fittings, joint construction, testing, and other aspects of piping systems. Various industries, including oil and gas, petrochemical, chemical, and power generation, are always in compliance with ASME B313 standards as a way to ensure the safety and reliability of piping systems.

What Is ASME B31.3 Process Piping?

ASME B31.3 is a code for pressure piping commonly used in places like petroleum refineries, chemical, pharmaceutical, hydrogen, textile, paper and pulp, power generation, semiconductor, and cryogenic plants, as well as related processing plants and terminals. The latest version is 2022 Edition.

ASME B31.3 focuses on the design, fabrication, installation, inspection, testing, and maintenance of process piping systems. The B313.3 code applies to all fluids piping, including:

  • Raw, intermediate, and finished chemicals
  • Fluidized solids
  • Gas, steam, air, and water
  • Refrigerants
  • Cryogenic fluids

What Is Fluid Service Category in ASME B31.3?

ASME B31.3 includes various fluid service types to categorize fluids based on their characteristics. These fluid service types are defined to ensure proper design, construction, and maintenance of process piping systems. The fluid service types outlined in ASME B31.3 are as follows:

1. Category D

Category D Fluid Service Fluid services that meet the specified requirements are classified as Category D within ASME B31.3.

  1. The fluid being handled must be non-flammable, non-toxic, and non-harmful to human tissues.
  2. The design pressure should not exceed 150 psi (approximately 10 bar). This indicates that this service deals with moderate pressure levels, considering the typical atmospheric pressure is around 15 psi (approximately 1 bar).
  3. The design temperature ranges from -29 to 186 degrees Celsius. Similar to pressure, this service operates within moderate temperature ranges.

Category D Fluid Service typically includes utility lines such as water, air, and similar substances. Piping for this service follows the design guidelines outlined in ASME B 31.3, chapters I to VI for metallic piping and chapter VII for non-metallic and lined piping.

piping engineer
Piping Designer and Engineer follows ASME B31.3 Standard (Credit: Vecteezy)

2. Category M

Category M fluid refers to highly toxic substances that can cause permanent harm even with minimal exposure resulting from leakage, even if immediate actions are taken.

Therefore, any fluids falling into this category, along with those identified by the facility owner based on their experience, that are deemed to require additional leak tightness measures beyond what is specified for Normal Fluid Service, are included in this group.

When designing piping for Category M fluid service, you must adhere to the guidelines outlined in Chapter VIII of ASME B 31.3. It is essential to incorporate sufficient safeguards to ensure the safety of personnel.

3. High-Pressure Fluid service

According to ASME B31.3, a fluid service that necessitates the utilization of Chapter IX for piping design and construction is called a high-pressure fluid service.

Typically, any service that demands a flange class surpassing 2500 is classified as a high-pressure fluid service.

It is important to note that the use of non-metallic or metallic-lined piping components is not allowed in the high-pressure piping category.

4. Elevated Temperature Fluid Service

ASME B31.3 states that a fluid service falls under the category of Elevated temperature when the metal temperature of the piping is consistently equal to or higher than Tcr.

Tcr is the corrected temperature, which is 25°C lower than the temperature at which time-dependent properties, such as creep, become significant in a material. When the design temperature is sufficiently high to impact stress values, it is considered an Elevated temperature fluid service.

When designing piping for Elevated temperature fluid service, it is crucial to take this mechanical property into account to ensure a safe design.

5. High Purity Fluid Service

As per ASME B31.3, a fluid service that necessitates special fabrication methods, inspection, examination, and testing, and is not addressed elsewhere in the Code, is intended to achieve a specific level of cleanliness.

In cases where the process fluid demands an extremely clean environment to prevent any impurities caused by metals, additional standards are employed for the design of such piping systems. Industries like pharmaceuticals and food processing may require this level of cleanliness in their piping systems, which are categorized as high purity, ultra-high purity, hygienic, or aseptic.

6. Normal Fluid Service

In line with its name, a fluid service that does not fall into any of the previously mentioned categories is classified as a normal service. After considering the categories of high pressure, temperature, purity, Category D, and Category M, any remaining fluid service is deemed as a normal service.

These classifications provide crucial guidance and requirements for designing, constructing, and operating piping systems in diverse industrial sectors. By familiarizing yourself with these types, you can make informed decisions regarding material selection and maximize pipeline production and maintenance in the industry. Reserve your spot in our ASME B31.3 training and increase efficiency in the process of piping with PetroSync!

What Are The Content of ASME B31.3 Standards?

ASME B31.3 is a widely recognized code published by the American Society of Mechanical Engineers (ASME) that provides guidelines and requirements for the design, construction, and operation of process piping systems. Here is a short summary of its contents:

1. The Scope

It outlines the areas where the code is applicable, including the specific types of piping systems that it covers.

2. The Definitions

This section provides an extensive compilation of explanations for important words and phrases utilized within the code.

3. The Design Conditions

It establishes the necessary guidelines for identifying the design conditions, including factors like pressure, temperature, and material choice.

4. The Materials

It addresses the process of choosing, specifying, and understanding the limitations of materials used in process piping systems.

5. The Design

This section offers guidelines for the design of piping systems, including considerations for pressure, temperature, support structures, flexibility, and analysis of stress.

6. The Fabrication, Assembly, and Erection

It sets out the necessary specifications for the fabrication, assembly, and erection of piping systems, which include procedures for welding, inspection, and testing.

7. The Inspection, Examination, and Testing

It encompasses the procedures and criteria for inspecting, examining, and testing piping systems, including methods for non-destructive examination.

8. The Pressure Testing

It provides instructions on performing pressure tests on piping systems to guarantee their integrity and safety.

9. The Nonmetallic Piping and Piping Lining

It incorporates specifications and recommendations for nonmetallic piping and the materials used for lining piping systems.

10. The Vibration

It covers the assessment and mitigation of vibration issues in piping systems to prevent failures.

11. The Failure Analysis

This section offers guidance on investigating and analyzing failures in piping systems to determine the underlying causes and prevent them from happening again.

12. The Maintenance and Operation

This topic provides suggestions for maintaining and operating piping systems to ensure their ongoing reliability and integrity.

13. The Nonmandatory Appendices

It contains supplementary information, examples, and guidance that are not obligatory but can be beneficial in comprehending and implementing the code.

It’s important to note that this summary provides a general overview of ASME B31.3, but the actual code contains much more detailed and specific requirements for the design, construction, and operation of process piping systems.

How is the Piping System Following ASME B31.3 Standard?

ASME B31.3 contains policy of process piping
ASME B31.3 discuss about process piping (Credit: Freepik)

Apart from adhering to the code requirements, any piping engineer has to be compliant with good design practices to ensure that the piping systems’ greatest performance is achieved. These principles are essential for ensuring the safety and cost-effectiveness of the piping systems.  According to ASME B31.3 Process Piping Guide 2020 Edition, a good piping system must consider all aspects such as:

  1. Qualification of The Designer
  2. Design Pressure
  3. Design Temperature
  4. Ambient Effect
  5. Dynamic Effect
  6. Weight Effect
  7. Thermal Expansion and Contraction Effect
  8. Effects of Support, Anchor, and Terminal, Movements
  9. Reduced Ductility Effects, and
  10. Cyclic effect.

What Is The Difference in ASME B31.1 and B31.3?

Both ASME B31.1 and B31.3 provide guidelines for piping design aspects but are different in design considerations. Below are some distinctions that occur between the standards.

Parameter ASME B31.3 – Process Piping ASME B31.1 – Power Piping
Scope Provides rules for process or chemical plants Provides rules for power plants
Factor of Safety Level 3 Factor of Safety Level 4 Factor of Safety
Equation for Pipe Wall Thickness Calculation The equation for pipe wall thickness calculation is valid for t<D/6 No limitation in power piping wall thickness calculation, but the maximum design pressure has limitations.
Design Life designed for 20 to 30 years of service life designed for 40 years or more of service life


Alternatively, you have the option to view the provided video, which delves into an insightful comparison between ASME B31.1 and ASME B31.3.

What Is ASME B31.3 Latest Update?

Since 2014, ASME B31.3 has been regularly updated every two years. The latest edition is ASME B31.3-2022 which updates the 2020 edition of the process piping standard. Cited from ANSI, here are some of the many critical changes for the past 8 years:

1. ASME B31.3 Latest Edition 2022: Changes from the 2020 Edition

  • Updates on the glossary section, including the definitions of construction, designated lot, combination welded (COW) pipe, post-weld hydrogen bakeout, and set pressure, alongside revisions to some of the previously listed definitions.
  • Further explanation was included regarding progressive sampling for examination purposes.
  • Table 323.2.2A, “Tabular Values for Minimum Temperatures Without Impact Testing for Carbon Steel Materials,” underwent a complete revision.
  • Stress Range Factor (para. 302.3.5) – revision
  • Fillet Welds (para. 328.5.2) – revision
  • Fabricated Laps (para. 328.5.5) – revision
  • Attachment Welds (para. 328.7 & 341.4) – revision
  • Postweld Hydrogen Bakeout (paras. 300.2 & 331.1.2) – revision
  • Progressive Sampling for Examination (para. 341.3.4) – revision
  • Weld Acceptance Criteria (Table 341.3.2) – revision
  • Examination Personnel Qualification (para. 342.1) – revision
  • Leak Test Gauges (para. 345.2.2(d)) – revision
  • Pneumatic Leak Test Preliminary Check (para. 345.5.5) – revision
  • Weld Coupon Examination (para. U341.4.5) – revision
  • External Loads on Flanges (para. F312.1) – revision
  • Allowable Stresses for High Pressure Piping (Appendix K) – revision

2. ASME B31.3 2020: Changes from the 2018 Edition

  • The ASME B31 Code was updated to clarify that it covers the criteria for the examination, inspection, and testing of piping in addition to its broad scope.
  • Appendix D, “Flexibility and Stress Intensification Factors,” was removed from the 2018 edition standard.
  • Appendix F includes the bonding of plastics

3. ASME B31.3 2018: Changes from the 2016 Edition

  • The entire range of Chapter IX, “High-Pressure Piping,” underwent a complete revision.
  • The complete content of Appendix Z, “Preparation of Technical Inquiries,” was revised.
  • K315, “Tubing Joints,” included instructions for flared end tubing joints

4. ASME B31.3 2016: Changes from the 2014 Edition

  • The code permits either MPa (megapascal) or ksi (kilopound per square inch).
  • The standards for accepting ultrasonic examinations were added.
  • New instructions concerning severe cyclic conditions were included, or “Conditions applying to specific piping components or joints for which the owner or the designer determines that construction to resist fatigue loading better is warranted.”

In conclusion, the code has been updated regularly since 2014, with critical changes including acceptance of MPa or ksi, new standards for ultrasonic examinations, and instructions for severe cyclic conditions.

The 2018 edition saw a complete revision of Chapter IX and Appendix Z, and instructions for flared end tubing joints. The latest 2022 edition includes updates to the glossary and further explanation of progressive sampling.

Who Can Make The Most Out of ASME B31.3?

You can benefit from ASME B31.3 if you’re involved in various roles related to piping installations in facilities, for instance:

  • As a Piping Designer, you ensure that piping systems meet the code’s requirements and any additional ones set by the owner, using your engineering judgment during the design process.
  • If you’re a Piping Manufacturer, Fabricator, or Erector, your responsibility lies in providing materials, components, and workmanship that align with the B31.3 code and engineering design specifications.
  • Owner’s Inspectors oversee that inspection, examination, and testing meet the code’s standards. They also ensure the effective implementation of any quality systems specified by the owner.

In What Industry ASME B31.3 Is Used?

ASME B31.3 is used in various industries, including:

  • Food and Beverage Processing Facilities
  • Petroleum Refineries
  • Natural Gas Production Facilities
  • Oil & Gas Onshore and Offshore Petroleum Plants
  • Chemical, Pharmaceutical, Textile, Paper, Ore Processing Semiconductor and Cryogenic Plants
  • Any related Processing Plants and/or Terminals

Attending ASME B31.3 Process Piping Code Design Requirements training course can be an essential option for you as piping engineers, designers, or any plant operation personnel assigned to the refineries and petrochemical plants.

You can stay up-to-date with the knowledge in process piping while obtaining comprehensive knowledge about ASME B31.3 by joining our intensive 5-day ASME B31.3 training. Join us now and learn from experienced instructors within the petroleum industry!

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