Codes and Standards

Some Important Piping Codes and Standards

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Piping codes and standards are the main pillars of any piping industry. As, the integrity of the piping system depends upon the considerations and principles used for designing, construction, inspection, and maintenance of the system. In practice, the assurance that the design and construction of a piping system will meet safety requirements is achieved through the use of published engineering codes and standards.

Piping systems are made of components like pipes, fittings, flanges, gaskets, bolts, nuts, valves, strainers, piping supports, and special parts such as steam traps, bellows, flame arresters, hoses, sight glasses, etc. These piping components can be made in a variety of materials, in different manufacturing processes, in different types and sizes. These different processes can be achieved with defined codes and standards.

In these articles, we will see some major piping codes and standards and their application.

Difference Between Codes and Standards


Codes and standards both provide the engineering criteria or method through which the piping integrity can be ensured and it simplifies the design consideration to make sure adherence to the standards. Many of us (the designers and engineers) think that the terms code and standard are synonymous, but this understanding is incorrect. Let’s understand the difference below.


The piping codes provide specific design criteria for the activities such as material (MOC) selection, checking of allowable working stresses, and load criteria that must be considered for design per the particular application.

In addition, criteria are provided to determine the minimum pipe wall thickness, material behavior due to the effects of internal or external pressure, dead weight, seismic loads, live loads, and thermal expansion/contraction.

Piping codes provide design rules for non-standard fittings like miter bend and also for the reinforcement pad of stub-in or stub-on piping branch connections. Piping Codes do not provide design consideration for standard fittings or components such as elbows, tees, flanges, valves, olets fittings, etc.

Example of Codes

ASME B31.1, ASME B31.3, ASME B31.4, etc.


Standards provide the design criteria and rules for individual piping components or fittings, and also the Class (pressure-temperature ratings) selection criteria of piping components such as flanges, valves, gasket, bolts and nuts.

There are mainly two types of standards:

  • Dimensional Standards
  • Pressure-temperature based standards

Dimensional standards provide dimensional parameters for the particular piping components. The main purpose of dimensional standards is to ensure the same dimensions for similar components manufactured by different vendors to achieve interchangeability. Some components are also manufactured per the manufacturing standards.

Pressure-temperature based standards are used for the rating based components which provides the maximum pressure holding capacity of that particular component.

Example of Standards

ASME B16.9, ASME B16.10 ASME B16.5, etc.

What do You Mean by Recommended Practices?

Recommended practices are the documents prepared by a professional group, committee, or company based upon good engineering practices held in the industry. Many companies also generate their own recommended practices based upon the old projects. In order to have consistency in design and to avoid having one project differ from others for cost-effectiveness.

Benefits of Referring Codes and Standards

  • Codes and standards provide single direction thinking to all.
  • It ensures the safety and reliability of the system.
  • The local government shows the green signal only if the plant is designed under the published codes and standards.
  • It creates a similarity in engineering considerations, terms, principles, practices, materials, processes, etc.
  • Standardization to the way of working.
  • It minimizes mismatching and promote the interchangeability.
  • Helps to reduce the cost of the projects.
  • Code & standards make ease of communicating within the different engineering departments.

Now, we will see the different types of Piping codes and standards, recommended practices, and their applications below-

Pressure Piping Codes

The American Society of Mechanical Engineers (ASME) established the ASME B31 Pressure Piping Code to ensure the safety of the pressure piping system design and construction through published engineering rules.

Followings are the some major pressure piping codes-

ASME B31.1 Power Piping

ASME B31.1 Code is mainly used for the design and construction of power piping of Electric Power Generating Stations, Industrial & Institutional Plants, Geothermal Heating Systems, and Central & District Heating and Cooling Systems.

ASME B31.3 Process Piping

ASME B31.3 Code is mainly applicable to the design and construction of pressure piping found in Petroleum Refineries, Chemical plant, Pharmaceutical, Food, Textile, Paper, Paint, Cryogenic, and any Process Plants and Terminals.

ASME B31.4 Hydrocarbon Transportation Pipeline

ASME B31.4 Code is applicable for the pipelines that are used to transport liquids between plants, terminals, and pumping regulating stations. These liquids include crude oil, condensate, natural gasoline, liquefied petroleum gas, carbon dioxide, liquid alcohol, and liquid petroleum products. For example the pipeline from upstream to midstream or downstream.

ASME B31.5 Refrigeration Piping and Heat Transfer Components

ASME B31.5 Code is applicable for the design and construction of pressure piping containing refrigerants or coolants. It is mainly used for HVAC piping system.

ASME B31.8 Gas Transportation and Distribution Piping Systems

ASME B31.8 Code is applicable for gas transportation pipelines between the sources and terminals. It also applies to gas pipelines, gas compressor stations, gas metering & regulation stations.

ASME B31.8 deals with the design, construction, inspection, operation, and maintenance of gas transportation pipeline, but it does not deal with auxiliary piping, such as water, air, steam, or lubricating oil.

ASME B31.9 Building Services Piping

ASME B31.9 Code is used for the design and construction of piping found in Industrial, Institutional, Commercial, Public Buildings, and multi-unit residences which do not require the different range of pipe sizes.

ASME B31.11 Slurry Transportation Piping Systems

ASME B31.11 Code is mainly applicable to transport slurry of non-hazardous materials, such as coal, mineral ores, and other solids, between the slurry process plants and process piping system. One of the important uses of these pipelines is in the mining industries to move ores from the mines to elsewhere.


There are many similarities in each Code, such as minimum pipe wall thickness calculation, inspection, and testing. But the exact rules are different for each code depending upon their application. The allowable stresses are different for each code, reflecting a different factor of safety per the different applications and operating conditions.

ASME Standards for Piping Components or Fittings

The below standards are used for design, dimensions, manufacturing processes, and end preparation for many commonly used piping components under ASME B31.3 process piping systems.

ASME B16.1 – Cast Iron Flanges and Flange End Fittings
ASME B16.3 – Malleable Iron Threaded Fittings of class 150 & 300
ASME B16.4 – Cast Iron Threaded Fittings of Class 125 & 250
ASME B16.5 – Flanges and Flanged Fittings
ASME B16.9 – Factory-Made Wrought Steel Buttwelding Fittings
ASME B16.10 – Face to Face and End to End Distance of Valves Except for Socket & Threaded End
ASME B16.11 – Forged Fittings, Socket Weld and Threaded, Socket weld End Preparation
ASMEB 16.12 – Cast Iron Threaded Drainage Fittings
ASME B16.15 – Cast Bronze Threaded Components of Class 125 & 250
ASME B16.18 – Copper Alloy Solder Joint Pressure Fittings
ASME B16.20 – Metallic Gasket
ASME B16.21 – Nonmetallic Gasket
ASME B16.25 – Buttweld or Bevel End Preparation
ASME B16.26 – Copper Alloy Components for Flared Copper Tubes
ASME B16.28 – Wrought Steel Buttweld Short Radius Elbows and Bend
ASME B16.34 – Valves Design – Flanged, Threaded, and Welding End
ASME B16.36 – Orifice Flanges
ASME B16.37 – Hydrostatic Testing of Control Valves
ASME B16.39 – Malleable Iron Threaded Pipe Unions, Classes 1150, 250 and 300
ASME B16.42 – Ductile Iron Flanges and Flange End Fittings of Class 150 & 300
ASME B16.44 – Manually Operated Metallic Gasket Valves for Building piping system
ASME B16.45 – Cast Iron Components for Solvent Drainage Systems
ASME B16.47 – Large Diameter Steel Flanges (NPS 26″ through NPS 60″)
ASME B16.48 – Steel Line Blanks
ASME B1.20.1 – Threading End Preparation
ASME B18.20.1 – Dimensions of Stud Bolts and Machine Bolts
ASME B18.20.2 – Dimensions of Nuts

API – American Petroleum Institute

API 5L – Line Pipe
API 6D – Pipeline Valves
API 6FA – Fire Test for Valves
API 12D – Field Welded Tanks for Storage of Finish Products (liquid)
API 12F – Shop Welded Tanks for Storage of Finish Products (liquid)
API 12J – Oil and Gas Separators
API 520 – Pressure Safety Valve
API 594 – Wafer and Wafer-Lug Check Valves
API 598 – Valve Inspection and Testing
API 599 – Plug Valves – Flanged and Butt-Weld Ends
API 600 – Gate Valves-Flanged and Butt-Weld Ends
API 602 – Small Bore Steel Gate Valves-Flanged, Threaded, or Buttweld End
API 608 – Ball Valves-Flanged and Butt-Weld Ends
API 609 – Lug-and Wafer-Type Butterfly Valves
API 610 – Centrifugal Pumps
API 617 – Centrifugal Compressors
API 618 – Reciprocating Compressors
API 619 – Rotary-Type Positive Displacement Compressors
API 620 – Design and Construction of Low-Pressure Storage Tanks
API 650 – Breather Valve
API 660 – Heat Exchangers used for General Refinery Service
API 661 – Air-Cooled Fin-fan Heat Exchangers used for General Refinery Service

ASTM – American Society of Testing Materials

ASTM provides a collection of documents called material specifications for pipes and piping components.

  • Specifications starting with “A” denotes Ferrous steel
  • Specifications starting with “B” denotes non-ferrous alloys
  • Specifications starting with “D” denotes plastic material

ASTM codes specify the basic chemical composition of the material and the manufacturing process through which the material is shaped into the finished product. Some of the common material standards are:

  • ASTM A 53 Gr. B – CS (Carbon Steel)Seamless and Welded Pipe
  • ASTM A106 Gr. B CS Seamless Pipe
  • ASTM A 672 Gr. B60 CS Welded Pipe (EFW)
  • ASTM A333 Gr. 6 – LTCS (Low-Temperature Carbon Steel) Seamless and Welded Pipe
  • ASTM A671 Gr. CC60 – LTCS Welded Pipe
  • ASTM A335P11, P22, P5, P9, P91 & P92 – LAS (Low Alloy Steel) Seamless Pipe
  • ASTM A691 – LAS Welded Pipe
  • ASTM A 312TP304, TP316, TP321 & TP347 – SS (Stainless Steel) Seamless & Welded Pipe
  • ASTM A358 Gr. 304, 316, 321 & 347 – SS Welded Pipe
  • ASTM A105 – CS Forged Fittings
  • ASTM A350 Gr. LF2 – LTCS Forged Fittings
  • ASTM A182 Gr. F11, F22, F5, F9, F91 &F92 – LAS Forged Fittings
  • ASTM A182 Gr. F304, F316, F321 & F347 – SS Forged Fittings
  • ASTM A234WPB – CS Wrought Fittings
  • ASTM A420 Gr. WPL6 – LTCS Wrought Fittings
  • ASTM A234 Gr. WP11, WP22, WP5, WP9, WP9 & WP92 – LAS Wrought Fittings
  • ASTM A403 Gr. WP304, WP316, WP321 & WP347 – SS Wrought Fittings
  • ASTM A216 Gr.WCB – CS Casted Fittings
  • ASTM A352 Gr.LCB – LTCS Casted Fittings
  • ASTM A217 Gr. WC6, WC9, C5, C12, & C12A – LAS Casted Fittings
  • ASTM A351 Gr.CF8, CF8M & CF8C – SS Casted Fittings
  • ASTM A515 Gr. 60 – CS Plate/Sheet
  • ASTM A516 Gr. C60 – LTCS Plate/Sheet
  • ASTM A387 Gr. 11, 22, 5, 9, 91 &92 – LAS Plate/Sheet
  • ASTM A240 Gr. 304, 316, 321 & 347 – SS Plate/Sheet
  • ASTM A193 Gr. B7 – Bolt used with CS Fittings
  • ASTM A320 Gr. L7 – Bold used with LTCS Fittings
  • ASTM A193 Gr. B16 – Bolt used with LAS Fittings
  • ASTM A515 Gr. B8 – Bolt used with SS Fittings
  • ASTM A194 Gr. 2H – Nut used with CS Fittings
  • ASTM A194 Gr. 4 – Nut used with LTCS Fittings
  • ASTM A194 Gr. 4 – Nut used with LAS Fittings
  • ASTM A194 Gr. 8 – Nut used with SS Fittings

AWS – American Welding Society

AWS provides information on the welding procedure, different weld application, weld design, welder training, testing, and inspection of the weld joints. Click here to see the different welding positions 1G, 2G, 5G & 6G.

  • AWS D10.12 – For Pipe welding (mild steel)
  • AWS D10.18 – For Pipe welding (stainless steel)
  • AWS B1.10 – Procedure for the nondestructive testing of welds
  • AWS B2.1 – Guide for Welding Procedure and welder Qualification

AWWA – American Water Works Association

AWWA standards are applicable to the piping elements required for low-pressure water services. Few commonly used standards are as follows-

  • AWWA C-207 – Flanges for General Services (4″ to 144″ NPS
  • AWWA C-500 – Gate Valves for Water and Sewage system
  • AWWA C-502 – Dry-Barrel Fire Hydrants
  • AWWA C-503 – Wet-Barrel Fire Hydrant
  • AWWA C-504 – Rubber Seated Butterfly Valves
  • AWWA C-507 – Ball Valves for Size Range 6″ to 48″ NPS
  • AWWA C-508 – Swing Check Valves 2″ to 24″ NPS
  • AWWA C-509 – Resilient Seated Gate Valves for water and sewage
  • AWWA C-510 – Cast Iron Sluice Gate Valves
  • AWWA C-900 – PVC Pressure Pipe, 4″ to 12″ NPS for Water services

MSS-SP: Manufacturers Standardization Society – Special Practices

The most common MSS-SP standards are mentioned below-

MSS-SP 6 Flange Face Finish
MSS-SP 25 Marking Procedure for Valves, Piping Components, and Flanges MSS-SP 42 – Corrosion-resistant of Class 150 Gate, Globe and Check Valves
MSS-SP 43 – Stud End
MSS-SP 56 – Procedure for Design, Manufacturing, and Material Selection, of Hanger-Supports
MSS-SP 61 – Procedure for Pressure Testing of Valves
MSS-SP 67 For Butterfly Valves
MSS-SP 70 – For Cast Iron Gate valves
MSS-SP 71 – For Cast Iron Check Valves
MSS-SP 72 – For Ball Valves
MSS-SP 78 – Cast Iron Plug Valves
MSS-SP 80 – For Bronze Gate, Globe and Check Valves
MSS-SP 83 – Unions Fittings
MSS-SP 85 – For Cast Iron Globe Valves
MSS-SP 88 – For Diaphragm valves
MSS-SP 95 – Swaged Nipple
MSS-SP 97 – Olets Fittings, Click here to see the different type of Olets fittings and their application

Boiler and Pressure Vessel Code

ASME Section  I              Power Boilers
ASME Section  II            Materials Specifications
ASME Section  IV           Heating Boilers
ASME Section  V            Non-Destructive Examination
ASME Section  VIII        Pressure Vessels – Division 1 and Division 2
ASME Section  IX           Welding and Brazing Qualifications
ASME Section  X            Fibreglass-Reinforced Plastic Pressure Vessels

TEMA – Tubular Exchanger Manufacturing Association

TEMA is applicable for Heat Exchangers-

  • TEMA R – Heat Exchangers Used in Hydrocarbon Industry
  • TEMA C – Heat Exchangers Used in General Services
  • TEMA B – Heat Exchangers Used in Chemical Services

NACE – National Association of Corrosion Engineers

NACE standards apply to corrosion prevention and control and are used where corrosion is a key concern. NACE assists during the design, building, and operation of the piping system and minimizes the negative impacts of corrosion.


EJMA – Expansion Joint Manufacturing Association

The EJMA standards are used for the proper selection, manufacturing, and application of metallic bellows expansion joints.


IBR – Indian Boiler Regulations

IBR is the Indian Standard for design, operation, inspection, and maintenance of the Boiler.

These were the most commonly used piping codes and standards. There are more piping codes and standards other than listed above. I have listed the important ones.

Some Useful Topics
Pipe Thickness Calculation for Internal Pressure
Pipe Rack Design and Calculations
A Presentation on Pipe Insulation
A Presentation on Pipe Stress Analysis


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About Rehan Ahmad Khan

I'm a graduate in mechanical engineering, and a piping professional. I'm exploring this industry and having a great experience. In the process felt to share my knowledge with the other Piping Engineers and as a result, I am here with you.
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9 thoughts on “Some Important Piping Codes and Standards

  1. what is the procedure for PRECOMMISSIONING and what are the testing methods in pre commissionnig check list.

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