Table of Contents

What is Code?

Piping codes are defined as the requirements of design, fabrication, use of materials, tests and inspection of pipes and piping systems –

There are many definitions of the codes but to actually understand the Codes, we need to understand few facts about the codes which are listed below:

Important Facts about Codes:

  • Codes define what you need to do to establish a Process plant
  • A code has a limited jurisdiction defined by the code.
  • A code is not law but can be adopted into law.
  • Codes provide specific design criteria
    • for the activities such as material (MOC) selection,
    • checking of allowable working stresses, and loads
    • to determine the minimum pipe wall thickness,
    • material behaviour due to the effects of internal or external pressure, dead weight, seismic loads, live loads, and thermal expansion/contraction.
    • design rules for non-standard fittings like miter bend
    • for the reinforcement pad of stub-in or stub-on piping branch connections

Important ASME Pressure Piping Codes: 

ASME B31 Piping Codes

Starting with Project B31 in March 1926, the first edition of American tentative Standard Code for Pressure Piping was published in 1935. In view of continuous industry developments and increases in diversified needs over the years, decisions were made to publish several sections of the Code for Pressure Piping. Since December 1978, the American National Standards Committee B31 was reorganized as the ASME Code for Pressure Piping B31 Committee under procedures developed by the ASME and accredited by ANSI.

These codes are commonly used for the design of commercial power and industrial piping systems:

Piping codes developed by the American Society of Mechanical Engineers:

ASME B31.1 Power Piping

Piping found in electric power stations or power plants, in industrial and institutional plants, geothermal heating systems and central and district heating and cooling plants.

ASME B31.2 – 1968 – Fuel Gas Piping:

This has been withdrawn as a National Standard and replaced by ANSI/NFPA Z223.1, but B31.2 is still available from ASME and is a good reference for the design of gas piping systems (from the meter to the appliance).

ASME B31.3 Process Piping

Piping typically found in petroleum refineries, chemical, pharmaceutical, textile, per, semiconductor and cryogenic plants and related processing plants and terminals.

ASME B31.4 Pipeline Transportation Systems for Liquids

Piping transporting products between plants and terminals and within terminals, pumping, regulating, and metering stations.

ASME B31.5 Refrigeration Piping

Piping for refrigerants and secondary coolants.

ASME B31.8 Gas Transportation and Distribution Piping Systems

Piping transporting products which are predominately gas between sources and terminals including compressor, regulating, and metering stations, gas gathering pipelines.

ASME B31.9 Building Services Piping

Piping typically found in industrial, institutional, commercial and public buildings and in multi-unit residences which does not require the range of sizes, pressures and temperatures covered in B311.1

ASME B31.11 Slurry Transportation Piping Systems

Piping transporting aqueous slurries between plants and terminals within terminals, pumping and regulating stations.

ASME B31. 12 Standard on Hydrogen Piping and Pipelines 

It contains requirements for piping in gaseous and liquid hydrogen service and pipelines in gaseous hydrogen service.

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What are piping Standards?

Standards provide specific design criteria and rules for individual components or classes of components such as valves, flanges, and fittings.

Types of standards

There are two general types of standards:

  1. Dimensional Standards
  2. Pressure integrity Standards.
Dimensional standards
What are Dimensional Standards?

These establish the benchmarking for configuration control parameters i.e. dimensional parameters for piping components.

Purpose of Dimensional Standards

The main purpose of dimensional standards is to ensure & establish that similar piping components manufactured by different suppliers & vendors will be physically interchangeable.

Interesting Facts to be noted about Dimensional Standards

Conformity to a particular dimensional standard during the manufacture of a product does not establish the fact that all such similarly configured items will provide equal performance.

The fact can be explained with the example, Let’s take two valves of 10” with 300 Class, one from two different vendors or manufacturers. Now both the manufactures may follow the same Dimensional standard i.e. ASME B16.10, to establish the Face-to-Face and End-to-End Dimensions of Valves.

The valves would be physically interchangeable between 300# mating flanges in a particular piping system. But that doesn’t establish the fact that both the valves will perform the same way. There can be many reasons, there may be different seat and disk design, one valve might be capable of meeting far more stringent seat leakage criteria than the other.

Important ASME Dimensional Standards

Listed below are the most used piping-related dimensional standards:

  • ASME B1.20.1, Pipe Threads, General Purpose (Inch)
  • ASME B1.20.3, Dryseal Pipe Threads (Inch)
  • ASME B16.10, Face-to-Face and End-to-End Dimensions of Valves
  • ASME B16.20, Metallic Gaskets for Pipe Flanges—Ring Joint, Spiral Wound, and Jacketed
  • ASME B16.21, Non-Metallic Flat Gaskets for Pipe Flanges
  • ASME B16.25, Buttwelding Ends
  • ASME B36.10M, Welded and Seamless Wrought Steel Pipe
  • ASME B36.19M, Stainless Steel Pipe

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What are Pressure-integrity standards?

First of all, let’s try understanding what is pressure integrity? Pressure integrity can be defined the structural and leak resistant capability of a product to contain applied pressure.

Definition of Pressure-Integrity standard

Those standards which are based on Pressure-temperature rating, are furnished for the rating-based components which provides the maximum pressure holding capacity of that particular component. Hence, these standards provide minimum-performance criteria based on PT rating.

Interesting Facts to be noted about Pressure-Integrity Standards

All Components which are designed and manufactured to the same pressure-integrity standards will function in an equivalent manner which was not the case for dimensional standards.

The same can be explained with an example. Suppose, we consider flanges of 12” Class 150, which are constructed in accordance with ASME B16.5 from two different manufacturers. Once both the manufacturers confirm that the Pressure-integrity standard ASME 16.5 has been followed to manufacture the flanges, we can say that both the flanges will perform in an equivalent manner.

Important ASME Pressure-Integrity Standards

The standards listed below provide design and manufacturing criteria for many commonly used piping components.

  • ASME B16.1, Cast Iron Pipe Flanges and Flanged Fittings
  • ASME B16.3, Malleable Iron Threaded Fittings
  • ASME B16.4, Gray Iron Threaded Fittings
  • ASME B16.5, Pipe Flanges and Flanged Fittings (NPS ¹⁄₂ Through NPS 24)
  • ASME B16.9, Factory Made Wrought Steel Buttwelding Fittings
  • ASME B16.11, Forged Fittings, Socket-Welding and Threaded
  • ASME B16.15, Cast Bronze Threaded Fittings (Class 125 and 250)
  • ASME B16.18, Cast Copper Alloy Solder Joint Pressure Fittings
  • ASME B16.22, Wrought Copper and Copper Alloy Solder Joint Pressure Fittings
  • ASME B16.24, Cast Copper Alloy Pipe Flanges and Flanged Fittings (Class 150, 300, 400, 600, 900, 1500, and 2500)
  • ASME B16.26, Cast Copper Alloy Fittings for Flared Copper Tubes
  • ASME B16.28, Wrought Steel Buttwelding Short Radius Elbows and Returns
  • ASME B16.33, Manually Operated Metallic Gas Valves for Use in Gas Piping Systems up to 125 psig (Sizes ¹⁄₂ Through 2)
  • ASME B16.34, Valves—Flanged, Threaded and Welding End
  • ASME B16.36, Orifice Flanges
  • ASME B16.38, Large Metallic Valves for Gas Distribution (Manually Operated, NPS 2¹⁄₂ to 12, 125 psig Maximum)
  • ASME B16.39, Malleable Iron Threaded Pipe Unions, Classes 150, 250, and 300
  • ASME B16.42, Ductile Iron Pipe Flanges and Flanged Fittings, Classes 150 and 300
  • ASME B16.47, Large Diameter Steel Flanges (NPS 26 Through NPS 60)

What are Piping Specifications?

The Piping Specification, mostly abbreviated as Pipe Spec is a document that is prepared & finalized during the design phase of any project, although the same can be updated during the course of project.

Interesting Facts about Piping Specifications

  1. It provides the appropriate selection, specification and material grade of pipe and piping components for a given service in a particular project.
  2. It provides guidelines & instructions for maintenance and repair on a section of pipe
  3. The piping specifications becomes basis & act as the key to correct material selection.
  4. Prior to start of the any job, reference to the piping specification is essential to specify and use the correct materials.
  5. To ensure meeting of project requirements, the latest revision of the specification need to be referred.
  6. If a discrepancy is found at any stage of the project, it should be reported & revised suitably with the consent of relevant stakeholders.

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Examples of Piping Specifications

There are many specifications which prepared during initial phase of the project & during the life cycle of the project. Few of the important examples of the same are following:

Design Basis

Piping design basis provides guidelines for design of Plot plan, Equipment layout, Piping Layout and selection of materials. 

Piping Material Specification (PMS)

It provides the appropriate selection, specification and material grade of pipe and piping components for a given service.

Support Standards

This specification establishes not only support types but material, design, spacing criteria & loading criteria to be used in the manufacturing of standard pipe supports.

Valve Material Specifications

Valve Material Specifications (VMS) is a specification which talks about various valves in a project. It provides complete details of individual valve in the form of valve data sheets.

Specifications of Material Requisitions

MRs are the documents which are prepared to list out all the requirements (Technical & design) so that the manufacturers can understand the client’s requirements and offer them the best suitable required piping items.

What are Recommended Practices?

Recommended practices can be available from two sources:

Prepared by Professional Groups

Recommended practices are the documents prepared by professional group or committee indicating good engineering practices based on their past experience, learning from others projects. The Important point to Note here is these recommendations are only optional. 

Few examples

Shell or Aramco Standards, which are globally accepted as a best practices and are adopted in many of the clients in their projects.

Prepared by Companies

Companies also develop their own recommended practices in order to have consistency in design and to avoid having one project differ substantially from others.

Few examples

Most of the client companies or EPC companies develop their in-house specifications which can be used as benchmarking while developing the project specific best practices. For example most of the companies have QMS (Quality Management System) which contains a lot of technical documentation which is used not only at the initial stage of the project to refer the past experience and lesson learnt, but can also be used during audits to establish that the best practices have been followed.

What are differences between Codes and Standards

  • Based on above details, it can be concluded that the Codes explain the rules for what you need to do, Standards tell us how to do and specifications establishes the requirements of the company.
  • Code is a group of general rules or systematic procedures for design, fabrication, installation and inspection that are adopted by legal jurisdiction and made into law which is not the case for standards or specifications.
  • A code has the force of law unlike standards which are voluntarily accepted guidelines which become mandatory only when incorporated into a business contract.

Advantages of Having Codes and Standards

  • Codes and standards bring consistency to technical standards, terminology, principles, practices, materials, processes,
  • Helps users establish standard working
  • Working with Codes & Standards ensures built-in security, reliability, and continuity.
  • Its usage minimizes conflicts and promote compatibility.
  • Implementing the codes & Standards save on systems, reduce inventory, and ensure market-ready backups.
  • It really helps gather knowledge and add confidence
  • Helps avoid reinventing the wheel; at the same time can be utilised in the every unique project.

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