CODES and STANDARDS
For Piping Systems proper selection of of Material of Construction alongwith Specifications, Adherence to Codes and Standards is essential. Standardization reduces cost, confusion and inconvenience. Standards are published by Professional Societies, Committees and Trade Organizations. It is also accepted by Governments. The main objective is to have Standardization and Safety.
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.
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 mainly the standards by :
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 :
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 :
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 :
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.
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.
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.
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 :
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 alooy 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 Superheater 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
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 :
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.