Satish Lele


For Piping Systems, proper selection of Material of Construction along with Specifications, and Adherence to Codes and Standards is essential. Standardization reduces cost, confusion and inconvenience. Standards are published by Professional Societies, Committees and Trade Organizations. Code is also accepted by Governments. The main objective is to have Standardization and Safety.

  • CODE: A group of general rules or systematic procedures for Design, Fabrication, Installation and Inspection methods prepared in such a manner that Code can be adopted by legal jurisdiction and made into a law.

  • STANDARDS: Documents prepared by a Professional group or Committee which are believed to be good and proper Engineering Practices and which contain mandatory requirement.

  • RECOMMENDED PRACTICES: Documents prepared by professional group or committee indicating Good Engineering Practices but which are optional.

Companies also develop Guides in order to have consistency in the documentation. These cover various engineering methods which are considered good practices, without specific recommendations or requirements.

Codes and Standards, besides being regulations, might also be considered as Design Aids since they provide guidance from experts.

Each country has its own Codes and Standards. On global basis, American National Standards are the most widely used and compliance with those requirements are accepted world over. In India, other than American Standards, British and Indian Standards are also used for design and selection of Piping Systems.

  1. AMERICAN STANDARDS: Not all American Standards are issued directly by American National Standards Institute. The Material Standards are covered under ASTM (American Society for Testing and Materials) and Dimension Standards under ANSI (American National Standards Institute). Most of these Standards are adapted by ASME (American Society for Mechanical Engineers).
    The American Standards referred by Piping Engineers are:

    • The American Petroleum Institute (API) : The Standards referred by Piping Engineers are:

      1. API 5L - Specification for Line Pipe
      2. API 6D - Pipe Line Valves, End Closures, Connectors and Swivels
      3. API 6F - Recommended Practice for Fire Test for valves
      4. API 593 - Ductile Iron Plug Valves - Flanged Ends
      5. API 598 - Valve Inspection and Test
      6. API 600 - Steel Gate Valves
      7. API 601 - Metallic Gaskets for Refinery Piping
      8. API 602 - Compact Design Carbon Steel Gate Valves
      9. API 604 - Ductile Iron Gate Valves - Flanged Ends
      10. API 605 - Large Diameter Carbon Steel Flanges
      11. API 607 - Fire Test for Soft Seated Ball Valves
      12. API 609 - Butterfly Valves
      13. API 1104 - Standard for Welding Pipeline and Facilities
    • The American Iron and Steel Institute (AISI) : These specify the material by its Chemical and Physical properties. When specific model of manufacture of the element is not to be specified, then the material can be identified by ANSI Standards. The most commonly used AISI specifications are :

      1. AISI 410 - 13% Chromium Alloy Steel
      2. AISI 304 - 18/8 Austenitic Stainless Steel
      3. AISI 316 - 18/8/3 Austenitic Stainless Steel
    • American National Standard Institute (ANSI) and The American Society for Mechanical Engineers (ASME) : The American National Standards Institute's standards used in the design of the Piping Systems are :

      1. B31.1 - 2001 - Power Piping: Piping for industrial plants and marine applications. This code prescribes minimum requirements for the design, materials, fabrication, erection, test, and inspection of power and auxiliary service piping systems for electric generation stations, industrial institutional plants, central and district heating plants.
        The code covers boiler external piping for power boilers and high temperature, high pressure water boilers in which steam or vapor is generated at a pressure of more than 15 pounds per square inch (PSIG) or 1 Kg per square centimeters, and high temperature water is generated at pressures exceeding 160 pounds per square inch (PSIG) or 12.5 Kg per square centimeters and / or temperatures exceeding 250 degrees F. (120 degrees C.)

      2. 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).

      3. B31.3 - 2002 - Process Piping : Design of chemical and petroleum plants and refineries processing chemicals and hydrocarbons, water and steam. This Code contains rules for piping typically found in petroleum refineries; chemical, pharmaceutical, textile, paper, semiconductor, and cryogenic plants; and related processing plants and terminals.
        This Code prescribes requirements for materials and components, design, fabrication, assembly, erection, examination, inspection, and testing of piping. This Code applies to piping for all fluids including:

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

        Also included is piping which interconnects pieces or stages within a packaged equipment assembly.
        The principal design codes used for piping design are the ANSI/ASME B31.1(Code for Power Piping) and ANSI/ASME B31.3 (Code for Process Piping). Complementing these codes are ASME VIII (Code for Pressure Vessel) and British Standard BS5500 for unfired fusion welded pressure vessel.
        The basic consideration of B31.1 Code is safety. Code includes:
        a. Material and component standards
        b. Designation of dimensional standards for elements of piping system
        c. Requirements for design of components, including supports
        d. Requirements for evaluation and limitation of stresses, reactions and movements associated with pressure, temperatures and external forces
        e. Requirements for fabrication, assembly and erection
        f. Requirements for testing and inspection before and after assembly.
        Pipes: For pipes, the materials used in geothermal application are normally A53-B, A106-B and API 5L-B pipe , with mill tolerance. Commercial available pipes normally have a mill tolerance of 12.5% and pipe schedule numbers based in B36.10.
        Fittings: For elbows, tees, and reducers, the material used in geothermal application is normally A234 WPB. All dimensions are in accordance with B16.9. Flanges and valves rating Flanges are rated to ANSI B16.5 standard, For those up to 24 diameter, they are rated to ANSI 150, ANSI 300, ANSI 600 and ANSI 900. For flanges of 26 and bigger , ANSI B16.47 applies. The flanges are usually classified series A and series B. The material used for these flanges are A181 grade I and A105 grade I. Valve rating is similar to the flange rating selected for the pipe.

      4. B31.4 - 2002 - Pipeline Transportation Systems for Liquid Hydrocarbons and Other Liquids : This Code prescribes requirements for the design, materials, construction, assembly, inspection, and testing of piping transporting liquids such as crude oil, condensate, natural gasoline, natural gas liquids, liquefied petroleum gas, carbon dioxide, liquid alcohol, liquid anhydrous ammonia and liquid petroleum products between producers' lease facilities, tank farms, natural gas processing plants, refineries, stations, ammonia plants, terminals (marine, rail and truck) and other delivery and receiving points.
        Piping consists of pipe, flanges, bolting, gaskets, valves, relief devices, fittings and the pressure containing parts of other piping components. Code also includes hangers and supports, and other equipment items necessary to prevent overstressing the pressure containing parts. Code does not include support structures such as frames of buildings, buildings stanchions or foundations.

      5. B31.5 - 2001 - Refrigeration Piping and Heat Transfer Components : This Code prescribes requirements for the materials, design, fabrication, assembly, erection, test, and inspection of refrigerant, heat transfer components, and secondary coolant piping for temperatures as low as -320 deg F (-196 deg C), whether erected on the premises or factory assembled, except as specifically excluded in the following paragraphs.
        Users are advised that other piping Code Sections may provide requirements for refrigeration piping in their respective jurisdictions. This Code shall not apply to:

        1. any self- contained or unit systems subject to the requirements of Underwriters Laboratories or other nationally recognized testing laboratory.

        2. water piping
        3. piping designed for external or internal gage pressure not exceeding 15 psi (105 kPa) regardless of size

        4. pressure vessels, compressors, or pumps, but does include all connecting refrigerant and secondary coolant piping starting at the first joint adjacent to such apparatus.

      6. B31.8 - 2003 - Gas Transmission and Distribution Piping Systems : This Code covers the design, fabrication, installation, inspection, and testing of pipeline facilities used for the transportation of gas. This Code also covers safety aspects of the operation and maintenance of those facilities.

      7. B31.8S-2001 - 2002 - Managing System Integrity of Gas Pipelines : This Standard applies to on-shore pipeline systems constructed with ferrous materials and that transport gas. Pipeline system means all parts of physical facilities through which gas is transported, including pipe, valves, appurtenances attached to pipe, compressor units, metering stations, regulator stations, delivery stations, holders and fabricated assemblies. The principles and processes embodied in integrity management are applicable to all pipeline systems. This Standard is specifically designed to provide the operator (as defined in section 13) with the information necessary to develop and implement an effective integrity management program utilizing proven industry practices and processes. The processes and approaches within this Standard are applicable to the entire pipeline system.

      8. B31.9 - 1996 - Building Services Piping : This Code Section has rules for the piping in industrial, institutional, commercial and public buildings, and multi-unit residences, which does not require the range of sizes, pressures, and temperatures covered in B31.1. This Code prescribes requirements for the design, materials, fabrication, installation, inspection, examination and testing of piping systems for building services. Code includes piping systems in the building or within the property limits.

      9. B31.11 - 2002 - Slurry Transportation Piping Systems : Design, construction, inspection, security requirements of slurry piping systems. Covers piping systems that transport aqueous slurries of no hazardous materials, such as coal, mineral ores and other solids between a slurry processing plant and the receiving plant.

      Of the above, the most commonly used code is ASME B 31.3. Refineries and Chemical Plants are designed based on the same. All Power Plants are designed as per ASME B31.1. Other major ANSI / ASME Standards refereed for the piping elements are :
      1. ANSI B 1.1 - Unified Inch Screw Threads
      2. ANSI / ASME B 1.20.1 - Pipe threads for general purposes
      3. ANSI / ASME B 16.1 - Cast Iron Pipe Flanges and Flanged Fittings
      4. ANSI / ASME B 16.3 - Malleable Iron Threaded Fittings
      5. ANSI / ASME B 16.4 - Cast Iron Threaded Fittings
      6. ANSI / ASME B 16.5 - Steel Pipe Flanges and Flanged Fittings
      7. ANSI / ASME B 16.9 - Steel Butt Welding Fittings
      8. ANSI / ASME B 16.10 - Face to Face and End to End dimensions of Valves
      9. ANSI / ASME B 16.11 - Forged Steel Socket Welding and Threaded fittings
      10. ANSI B 16.20 - Metallic Gaskets for Pipe Flanges - ring joint, spiral wound
      11. ANSI / ASME B 16.21 - Non Metallic Gaskets for Pipe Flanges
      12. ANSI / ASME B 16.25 - Butt Welding Ends
      13. ANSI / ASME B 16.28 - Short Radius Elbows and Returns
      14. ANSI / ASME B 16.34 - Steel Valves, Flanged and butt welding ends
      15. ANSI / ASME B 16.42 - Ductile Iron Pipe Flanges and Flanged Fittings - Class 150# and 300#
      16. ANSI / ASME B 16.47 - Large Diameter Steel Flanges - NPS - 26" to 60"
      17. ANSI / ASME B 18.2 1 and 2 - Square and Hexagonal head Bolts and Nuts (Inch and mm)
      18. ANSI / ASME B 36.10 - Welded and Seamless Wrought Steel Pipes
      19. ANSI / ASME B 36.19 - Welded and Seamless Austinitic Stainless Steel Pipe
    • American Society for Testing Materials (ASTM) : These consist of 16 sections on definitions and classifications of materials of construction and Test methods. Most of the ASTM Standards are adapted by ASME and are specified in ASME Section II. The Section II has four parts.

      • Part A - Ferrous Materials
      • Part B - Non-Ferrous Materials
      • Part C - Welding Materials
      • Part D - Properties of Materials

      In Section II, the materials are listed in the index based on the available forms such as plates, castings, tubes etc., and also on the numerical index.
      The selection of ASTM Specification depends on the manufacturer, form of material, its mechanical strength and corrosion properties.
      The specification number is given an Alphabetical prefix "A" for ferrous and "B" for non-ferrous materials.
      ASTM also specifies standard practice for numbering metal and alloys as Unified Numbering System.
      Unified Numbering System (UNS) establishes 18 series numbers of metals and alloys. Each UNS number consists of a single letter prefix followed by 5 digits. In most cases the alphabet is suggestive of the family of the metal identified.

      • A00001 - A99999 - Aluminum and Aluminum alloys
      • C00001 - C99999 - Copper and Copper Alloys
      • E00001 - E99999 - Rare earth and rare earth like metals and alloys
      • L00001 - L99999 - Low Melting metals and alloys
      • M00001 - M99999 - Miscellaneous non-ferrous metals and alloys
      • N00001 - N99999 - Nickel and Nickel Alloys
      • P00001 - P99999 - Precious Metals and Alloys
      • R00001 - R99999 - Reactive and Refractory metals and alloys
      • Z00001 - Z99999 - Zinc and zinc alloys
      • D00001 - D99999 - Specified mechanical properties of Steel
      • F00001 - F99999 - Cast Iron and Cast Steel
      • G00001 - G99999 - AISI and ASE Carbon and alloy steels
      • H00001 - H99999 - AISI H Steels
      • J00001 - J99999 - Cast Steel
      • K00001 - K99999 - Miscellaneous Steels and Ferrous alloys
      • S00001 - S99999 - Stainless Steel
      • T00001 - T99999 - Tool Steel
      • W00001 - W99999 - Welding Filler Metals and Electrodes
    • American Welding Society (AWS) : These standards provide information on the welding fundamentals, weld design, welder's training qualifications, testing and inspection of the welds and guidance on the application and use of welds. Individual electrode manufacturers have given their own brand names for the various electrodes and the same are sold under these names.

    • American Water Works Association (AWWA) : These standards refer to the piping elements required for low pressure water services. These are less stringent than other standards. Valves, Flanges etc., required for large diameter water pipelines are covered under this standard and are refereed rarely by piping engineers.

      • C-500 : Gate Valves for Water and sewage system
      • C-504 : Rubber Seated Butterfly Valves
      • C-507 : Ball Valves 6" to 48"
      • C-508 : Swing Check Valves 2" to 24"
      • C-509 : Resilient Seated Gate Valves for water and sewage
      • C-510 : Cast Iron Sluice Gate Valves
    • The manufacturers Standardization Society of Valves and Fitting Industry - Standard Practices (MSS-SP) : In addition to the above standards and material codes, there are standard practices followed by manufacturers. These are published as advisory standards and are widely followed. The most common MSS-SP standards referred for piping are :

      • MSS-SP-6 : Standard Finishes for contact surface for flanges
      • MSS-SP-25 : Standard marking system for valves, fittings, flanges
      • MSS-SP-42 : Class 150 corrosion resistant gate, globe and check valves
      • MSS-SP-43 : Wrought stainless steel butt weld fittings
      • MSS-SP-56 : Pipe hanger supports - Material, design and manufacture
      • MSS-SP-61 : Pressure testing of valves
      • MSS-SP-67 : Butterfly Valves
      • MSS-SP-68 : High Pressure off seat butterfly valves
      • MSS-SP-69 : Pipe hanger supports - selection and applications
      • MSS-SP-70 : Cast iron gate valves
      • MSS-SP-71 : Cast iron check valves
      • MSS-SP-72 : Ball Valves
      • MSS-SP-78 : Cast iron plug valves
      • MSS-SP-80 : Bronze gate, globe and check valves
      • MSS-SP-81 : Stainless steel bonnet-less knife gate valves
      • MSS-SP-83 : Pipe unions
      • MSS-SP-85 : Cast iron globe valves
      • MSS-SP-88 : Diaphragm valves
      • MSS-SP-89 : Pipe hangers and supports - fabrication and installation practices
      • MSS-SP-90 : Pipe hangers and supports - guidelines on terminology
      • MSS-SP-92 : MSS valves user guide
      • MSS-SP-108 : Resilient seated eccentric CI plug valves
  2. BRITISH STANDARDS: In many instances, it is possible to find a British Standard which may be substitutes for American Standards. For example, BS 2080 (British Standard for Face to Face or End to End dimensions of valves) is identical to ANSI/ASME B16.10. Similarly BS 3799 and ANSI/ASME B 16.11 also compare.
    There are certain British Standards referred by Indian Manufacturers for Piping and Valves. The most commonly referred British Standards in the Piping Industry are :

    • BS 10 : Flanges
    • BS 806 : Pipes and Fittings for Boilers
    • BS 916 : Black Bolts, Nuts and Screws
    • BS 970 : Steel for Forging, Bars, Rods, valve steel, etc.
    • BS 1212 : Specification for Float Operated Valves
    • BS 1306 : Copper and Copper alloy pressure piping system
    • BS 1414 : Gate Valves for Petroleum Industry
    • BS 1560 : Steel Pipe Flanges
    • BS 1600 : Dimensions of Steel Pipes
    • BS 1640 : Butt Welding Fittings
    • BS 1740 : Wrought Steel screwed pipe fittings
    • BS 1868 : Steel Check Valves for Petroleum Industry
    • BS 1873 : Steel Globe and Check Valves for Petroleum Industry
    • BS 1965 : Butt welding pipe fittings
    • BS 2080 : Face to Face / End to End dimensions of Valves
    • BS 2598 : Glass Pipelines and Fittings
    • BS 3059 : Boiler and Super-heater Tubes
    • BS 3063 : Dimensions of Gaskets for Pipe Flanges
    • BS 3381 : Metallic Spiral Wound Gaskets
    • BS 3600 : Dimensions of Welded and Seamless Pipes and Tubes
    • BS 3601 : C.S. Pipes and Tubes for pressure purposes at room temperature
    • BS 3602 : C.S. Pipes and Tubes for pressure purposes at high temperature
    • BS 3603 : C.S. and Alloy Steel Pipes and Tubes for pressure purposes at low temperature
    • BS 3604 : Alloy Steel Pipes and Tubes for high temperature
    • BS 3605 : SS Pipes and Tubes for pressure purposes
    • BS 3799 : Socket Weld / Screwed Fittings
    • BS 3974 : Pipe hangers, Slides and Roller type supports
    • BS 4346 : PVC pressure pipe - joints and fittings
    • BS 4504 : Steel, Cast Iron and Copper alloy fittings
    • BS 5150 : Cast Iron Wedge and Double Disc Gate Valves for general purposes
    • BS 5151 : Cast Iron Gate (parallel slide) Valves for general purposes
    • BS 5152 : Cast Iron Globe and Check Valves for general purposes
    • BS 5153 : Cast Iron Check Valves for general purposes
    • BS 5154 : Copper alloy Globe, Gate and Check Valves
    • BS 5155 : Cast Iron and Cast Steel Butterfly Valves for general purposes
    • BS 5156 : Diaphragm Valves for general purposes
    • BS 5157 : Steel Gate (parallel slide) Valves for general purposes
    • BS 5158 : Cast Iron and Cast Steel Plug Valves for general purposes
    • BS 5159 : Cast Iron and Cast Steel Ball Valves for general purposes
    • BS 5160 : Flanged Steel Globe and Check Valves for general purposes
    • BS 5163 : Flanged Cast Iron Wedge Gate Valves for general purposes
    • BS 5351 : Steel Ball Valves for Petroleum Industry
    • BS 5352 : Steel Gate, Globe and Check Valves, smaller than 2" NB
    • BS 5353 : Specifications for Plug Valves
    • BS 5391 : Specifications for ABS pressure pipes
    • BS 5392 : Specifications for ABS fittings
    • BS 5433 : Specifications for underground stop valves for water services
    • BS 5480 : Specifications for GRP pipes and fittings
    • BS 6364 : Specifications for Valves for Cryogenic services
    • BS 6755 : Testing of Valves
    • BS 6759 : Safety Valves
  3. INDIAN STANDARDS: Bureau of Indian Standards (BIS) have so far not developed an Indian Standard for the design of Piping Systems. Hence, ANSI Standards ASME 31.1 and 31.3 are widely used for the design. These standards also accept materials covered in other standards. Unlike American Standards, Indian Standards cover dimensions and material specifications under the same standard number. There are no groupings based on branch of engineering. Some of the most commonly referred Indian Standards by Piping Engineers are :

    • IS 210 : Grey Iron Castings
    • IS 226 : Structural Steel (superseded by IS 2062)
    • IS 554 : Dimensions of Pipe Threads
    • IS 778 : Specification for Copper Alloy Gate, Globe and Check Valves
    • IS 780 : Specification for Sluice Valves - 50 NB to 300 NB
    • IS 1239 (Part I and II) : Specification for Mild Steel tubes and fittings
    • IS 1363 : Hexagonal Bolts, Screws and nuts - Grade C
    • IS 1364 : Hexagonal Bolts, Screws and nuts - Grade A and B
    • IS 1367 : Technical supply conditions for threaded steel fastners
    • IS 1536 : Centrifugally Cast Iron Pipes
    • IS 1537 : Vertically Cast Iron Pipes
    • IS 1538 : Cast Iron Fittings
    • IS 1870 : Comparison of Indian and Overseas Standards
    • IS 1879 : Malleable Iron Pipe Fittings
    • IS 1978 : Lined Pipe
    • IS 1979 : High Test Line Pipe
    • IS 2002 : Steel Plates
    • IS 2016 : Plain Washers
    • IS 2041 : Steel Plates for Pressure Vessels used at moderate and low temperature
    • IS 2062 : Steel for general structural purposes
    • IS 2379 : Color Code for Identification of Pipelines
    • IS 2712 : Compressed Asbestos Fiber Jointing
    • IS 2825 : Code for Unfired Pressure Vessels
    • IS 2906 : Specification for Sluice Valves - 350 NB to 1200 NB
    • IS 3076 : Specification for LDPE Pipes
    • IS 3114 : Code of Practice for laying pipes
    • IS 3516 : Cast Iron flanges and flanged fittings for Petroleum Industry
    • IS 3589 : Seamless or ERW Pipes (150 NB to 2000 NB)
    • IS 4038 : Specifications for Foot Valves
    • IS 4179 : Sizes for pressure vessels and leading dimensions
    • IS 4853 : Radiographic Examination of Butt Weld Joints in pipes
    • IS 4864 to IS 4870 : Shell Flanges for vessels and equipments
    • IS 4984 : Specification for HDPE Pipes
    • IS 4985 : Specification for PVC Pipes
    • IS 5312 : Specification for Check Valves
    • IS 5572 : Classification of Hazardous area for Electrical Installation
    • IS 5822 : Code of practice for laying welded steel pipes
    • IS 6157 : Inspection and Testing of Valve
    • IS 6286 : Seamless and Welded pipes for Subzero temperatures
    • IS 6392 : Steel Pipe Flanges
    • IS 6630 : Seamless alloy steel pipes for high temperature service
    • IS 6913 : Stainless Steel tubes for food and beverage industry
    • IS 7181 : Horizontally cast iron pipes
    • IS 7240 : Code of Practice for Cold Insulation
    • IS 7413 : Code of Practice for Hot Insulation
    • IS 7719 : Metallic spiral wound gaskets
    • IS 7806 : Stainless Steel Castings
    • IS 7899 : Alloy Steel castings for pressure services
    • IS 8008 : Specification for molded HDPE Fittings
    • IS 8360 : Specification for fabricated HDPE Fittings
    • IS 9890 : Ball Valves for general purposes
    • IS 10221 : Code of Practice for coating and wrapping of underground MS pipelines
    • IS 10592 : Eye wash and safety showers
    • IS 10605 : Steel Globe Valves for Petroleum Industries
    • IS 10611 : Steel Gate Valves for Petroleum Industries
    • IS 10711 : Size of Drawing Sheets
    • IS 10805 : Foot Valves
    • IS 10989 : Cast / Forged Steel Check Valves for Petroleum Industry
    • IS 10990 : Technical drawings - Simplified representation of pipelines
    • IS 11790 : Code of Practice for preparation of Butt welding ends for valves, flanges and fittings
    • IS 11791 : Diaphragm Valves for general purposes
    • IS 11792 : Steel Ball Valves for Petroleum Industry
    • IS 12709 : Specifications for GRP pipes
    • IS 13049 : Specifications for Diaphragm type float operated valves
    • IS 13095 : Butterfly Valves
    • IS 13257 : Ring type joint gasket and grooves for flanges

    There are certain other international standards, which are also referred in Piping Industry. These are DIN standards of Germany and JIS standards of Japan. DIN standards are more popular and equivalent.
    Periodic review of the standards by the committee are done and these are revised to incorporate the modified features based on the research and feedback from industry. It is, hence, necessary that the latest editions of the codes and standards are referred for the design.

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