What Does MSS Mean in Piping Industry? List of MSS Standards (PDF)

The full form of MSS is the Manufacturers Standardization Society of the Valve and Fittings Industry. They are a non-profit technical association. Officially founded in the year 1924, the Manufacturers Standardization Society of the Valve and Fittings Industry (MSS) publishes various international codes and standards to ensure compliance, interoperability, safety, and operation of process piping systems for various industries like petroleum, petrochemical, food, beverage, and utility. The MSS standards mainly cover the following product segments:

  • Valves, Actuators, Valve modifications.
  • Pipe hangers.
  • Pipe fittings
  • Flanges
  • Seals, etc

With its 26 technical committees, MSS reviews and writes various useful industry standards. They have a wide range of participations including some of the most prestigious institutions like

  • American Society for Testing and Materials ASTM),
  • American Society of Mechanical Engineers (ASME),
  • American National Standards Institute (ANSI),
  • American Petroleum Institute (API),
  • American Waterworks Association (AWWA), and
  • the National Fire Protection Association (NFPA).

The Manufacturers Standardization Society of the Valve and Fittings Industry provides membership benefits to the member organizations including access to all their standards. Some of the standards and specifications developed by MSS are widely used in the piping industry. The standards developed by the MSS are provided with the term MSS followed by the term SP followed by the number and year of the latest publication (edition). Example; MSS SP-44-2019 or MSS SP-58-2018.

The following section will list the common MSS Standards that are extensively used in the Piping Industry.

List of MSS Standards

The following table lists some of the popular MSS standards:

MSS StandardDescriptionLatest Publication Year
MSS-SP-25Standard Marking System for Valves, Fittings, Flanges, and Unions2018
MSS-SP-44Steel Pipeline Flanges2019
MSS-SP-55Quality Standard for Steel Castings for Valves, Flanges, Fittings, and Other Piping Components – Visual Method for Evaluation of Surface Irregularities2011
MSS-SP-58Pipe Hangers and Supports – Materials, Design, Manufacture, Selection, Application, and Installation2018
MSS-SP-75High-Strength, Wrought, Butt-Welding Fittings2019
MSS-SP-86Recommended Rules and Guidelines for SI (Metric) Data in MSS Standards2021
MSS-SP-92Valve User Guide2021
MSS-SP-96Terminology for Valves, Fittings, and Their Related Components2017
MSS-SP-138Quality Standard Practice for Oxygen Cleaning of Valves and Fittings2014
MSS-SP-144Pressure Seal Bonnet Valves2020
MSS-SP-6Standard Finishes for Contact Faces of Pipe Flanges and Connecting-End Flanges of Valves and Fittings2021
MSS-SP-9Spot Facing for Bronze, Iron, and Steel Flanges2018
MSS-SP-42Corrosion-Resistant Gate, Globe, Angle, and Check Valves with Flanged and Butt Weld Ends (Classes 150, 300, & 600)2013
MSS-SP-43Wrought and Fabricated Butt-Welding Fittings for Low Pressure, Corrosion Resistant Applications2019
MSS-SP-45Bypass and Drain Connections2020
MSS-SP-51Class 150LW Corrosion Resistant Flanges and Cast Flanged Fittings2021
MSS-SP-53Quality Standard for Steel Castings and Forgings for Valves, Flanges, Fittings, and Other Piping Components – Magnetic Particle Examination Method2021
MSS-SP-54Quality Standard for Steel Castings for Valves, Flanges, Fittings, and Other Piping Components – Radiographic Examination Method2013
MSS-SP-60Connecting Flange Joints between Tapping Sleeves and Tapping Valves2021
MSS-SP-61Pressure Testing of Valves2019
MSS-SP-65High-Pressure Chemical Industry Flanges and Threaded Stubs for Use with Lens Gaskets2019
MSS-SP-67Butterfly Valves2022
MSS-SP-68High-Pressure Butterfly Valves with Offset Design2021
MSS-SP-70Gray Iron Gate Valves, Flanged and Threaded Ends2011
MSS-SP-71Gray Iron Swing Check Valves, Flanged and Threaded Ends2018
Table 1: MSS SP Standards
Common Piping Abbreviations (PDF)
Common Piping Abbreviations (PDF)

Other MSS Standards

Other MSS SP standards are listed below:

  • MSS-SP-72-2010a: Ball Valves with Flanged or Butt-Welding Ends for General Service
  • MSS-SP-78-2011: Gray Iron Plug Valves, Flanged, and Threaded Ends
  • MSS-SP-79-2018: Socket-Welding Reducer Inserts
  • MSS-SP-80-2019: Bronze Gate, Globe, Angle, and Check Valves
  • MSS-SP-81-2021: Stainless-Steel or Stainless-Steel-Lined, Bonnetless, Knife Gate Valves with Flanged Ends
  • MSS-SP-83-2018: Class 3000 and 6000 Pipe Unions, Socket Welding, and Threaded (Carbon Steel, Alloy Steel, Stainless Steel, and Nickel Alloys)
  • MSS-SP-85-2011: Gray Iron Globe & Angle Valves, Flanged and Threaded Ends
  • MSS-SP-87-1991(R1996 – Reinstated 2011): Factory-Made Butt-Welding Fittings for Class I Nuclear Piping Applications
  • MSS-SP-88-2021: Diaphragm Valves
  • MSS-SP-91-2009: Guidelines for Manual Operation of Valves
  • MSS-SP-93-2020: Quality Standard for Steel Castings and Forgings for Valves, Flanges, Fittings, and Other Piping Components – Liquid Penetrant Examination Method
  • MSS-SP-94-2020: Quality Standard for Ferritic and Martensitic Steel Castings and Forgings for Valves, Flanges, Fittings, and Other Piping Components – Ultrasonic Examination Method
  • MSS-SP-95-2018: Swage(d) Nipples and Bull Plugs
  • MSS-SP-97-2019: Integrally Reinforced Forged Branch Outlet Fittings: Socket Welding, Threaded, and Buttwelding Ends
  • MSS-SP-98-2020: Protective Coatings for the Interior of Valves, Hydrants, and Fittings
  • MSS-SP-99-2016a: Instrument Valves
  • MSS-SP-100-2020: Qualification Requirements for Elastomer Diaphragms for Nuclear Service Diaphragm Valves
  • MSS-SP-101-2014: Part-Turn Valve Actuator Attachment – FA Flange and Driving Component Dimensions and Performance Characteristics
  • MSS-SP-102-1989(R2001): Multi-Turn Valve Actuator Attachment – Flange and Driving Component Dimensions and Performance Characteristics
  • MSS-SP-104-2018: Wrought Copper, Solder-Joint Pressure Fittings
  • MSS-SP-105-2016a: Instrument Valves for Code Applications
  • MSS-SP-106-2019: Cast Copper Alloy Flanges, and Flanged Fittings: Class 125, 150, and 300
  • MSS-SP-108-2020, Resilient-Seated Cast Iron Eccentric Plug Valves
  • MSS-SP-109-2018, Weld-Fabricated, Copper Solder-Joint Pressure Fittings
  • MSS-SP-110-2010, Ball Valves Threaded, Socket-Welding, Solder Joint, Grooved and Flared Ends
  • MSS-SP-111-2020, Gray-Iron, and Ductile-Iron Tapping Sleeves
  • MSS-SP-112-2021, Quality Standard for Evaluation of Cast Surface Finishes – Visual and Tactile Method
  • MSS-SP-113-2021, Connecting Joints between Tapping Machines and Tapping Valves
  • MSS-SP-114-2018, Corrosion Resistant Pipe Fittings Threaded and Socket Welding Class 150 and 1000
  • MSS-SP-115-2017, Excess Flow Valves, NPS 1-1/4 and Smaller, for Fuel Gas Service
  • MSS-SP-116-2019, Service-Line Valves and Fittings for Drinking Water Systems
  • MSS-SP-117-2011, Bellows Seals for Globe and Gate Valves
  • MSS-SP-119-2010, Factory-Made Wrought Belled End Pipe Fittings for Socket-Welding
  • MSS-SP-120-2017, Flexible Graphite Packing Sealing for Rising Stem Valves
  • MSS-SP-122-2017, Plastic Industrial Ball Valves
  • MSS-SP-123-2018, Non-Ferrous Threaded and Solder-Joint Unions for Use with Copper Water Tube
  • MSS-SP-124-2020, Fabricated Tapping Sleeves
  • MSS-SP-125-2018, Check Valves: Gray Iron and Ductile Iron, In-Line, Spring-Loaded, Center-Guided
  • MSS-SP-126-2013, In-Line, Spring-Assisted, Center-Guided Check Valves (Carbon, Alloy Steel, Stainless Steel, & Nickel Alloys)
  • MSS-SP-127-2014a, Bracing for Piping Systems: Seismic-Wind-Dynamic Design, Selection, and Application
  • MSS-SP-128-2012, Ductile Iron Gate Valves
  • MSS-SP-129-2021, Copper-Nickel Fittings
  • MSS-SP-130-2013, Bellows Seals for Instrument Valves
  • MSS-SP-131-2017, Metallic Manually Operated Gas Distribution Valves
  • MSS-SP-132-2022, Compression Packing Systems for Instrument Valves
  • MSS-SP-134-2012, Valves for Cryogenic Service, including Requirements for Body/Bonnet Extensions
  • MSS-SP-135-2021, High-Pressure Knife Gate Valves
  • MSS-SP-136-2020, Ductile Iron Swing Check Valves
  • MSS-SP-137-2020, Quality Standard for Positive Material Identification of Metal Valves, Flanges, Fittings, and Other Piping Components
  • MSS-SP-139-2014, Copper Alloy Gate, Globe, Angle, and Check Valves for Low Pressure/Low-Temperature Plumbing Applications
  • MSS-SP-140-2021, Quality Standard Practice for Preparation of Valves and Fittings for Silicone-Free Service
  • MSS-SP-141-2012, Multi-Turn and Check Valve Modifications
  • MSS-SP-142-2012, Excess Flow Valves for Fuel Gas Service, NPS 1½ through 12
  • MSS-SP-143-2018, Live-Loaded Valve Stem Packing Systems
  • MSS-SP-145-2013, Metal Ball Valves for Low Pressure/Low-Temperature Plumbing Applications
  • MSS-SP-146-2019, High-Pressure Knife Gate Valves: Iron and Ductile Iron, Lug-, Wafer-, and Flange-Type
  • MSS-SP-147-2014, Quality Standard for Steel Castings Used in Standard Class Steel Valves – Sampling Method for Evaluating Casting Quality
  • MSS-SP-148-2019, Low-Pressure Flanged or Lugged Carbon Steel and Iron or Ductile Iron, Cast or Fabricated, Bonnetless, Knife Gate Valves without Liners
  • MSS-SP-149-2018, Preformed Elastomeric and Polytetrafluoroethylene (PTFE) V-Ring Packing Sets for Waterworks Valves
  • MSS-SP-150-2019, Valves for Use in Hydrogen Peroxide Service
  • MSS-SP-151-2021, Pressure Testing of Knife Gate Valves
  • MSS-SP-152-2022, Knife Gate Valves for Double Block and Bleed
  • MSS-SP-153-2017, Modification of New Water Works Valves
  • MSS-SP-154-2018, Low-Pressure Knife Gate Valves for Double Block and Bleed
  • MSS-SP-155-2018, Plastic-Lined Metal Valves
  • MSS-SP-156-2019, Ductile Iron, Metal-Seated, Non-Lubricated, Eccentric Plug Valves
  • MSS-SP-157-2020, Quality Standard for Phosphate Surface Protective Coatings for Valves, Fittings, and Related Steel Piping Components
  • MSS-SP-158-2021, Supplemental High-Pressure Gas Test Procedures for Valves
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Anup Kumar Dey

I am a Mechanical Engineer turned into a Piping Engineer. Currently, I work in a reputed MNC as a Senior Piping Stress Engineer. I am very much passionate about blogging and always tried to do unique things. This website is my first venture into the world of blogging with the aim of connecting with other piping engineers around the world.

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