Valves are everywhere, and we rightly need them to be. As the main switch regulating the passage of fluids, valves are a necessity for almost anything involving the movement of liquids and gases in contained areas. Valve systems are even a major component of natural processes, with four valves being found in the human heart to control movement of blood through the ventricles. In the simplest sense, valves keep us alive.
Valves are fabricated with the same level of quality that goes into the biological valves in our bodies, ideally never losing control of the piping system that they manage. They have applications in almost every industry, including but not limited to: the nuclear industry, petrochemical industry, waste management, and aerosols. With such a wide range of usage and high level of dependency, it is necessary that there are standard practices for valves at the manufacturing stage.
Standardization Society of the Valve and Fittings Industry (MSS)
The Manufacturers Standardization Society of the Valve and Fittings Industry (MSS) is a standards-developing organization devoted primarily to the advancement of the valve industry. For general use of valves, they have published ANSI/MSS SP-96-2011 - Guidelines on Terminology for Valves and Fittings and MSS SP-91-2009 - Guidelines for Manual Operation of Valves.
MSS also has published many different requirements catered for the production of specific valve types.
A ball valve is a quarter-turn valve that makes use of a ball pierced with an opening through the ball and fixed to rotate on a spindle. Excellent for tasks that require quick action in start/stop applications, these valves are commonly found in flowing systems on ships, chlorine manufacturing, fire safety services, chemical and non-sterile industries. However, since they cannot be easily cleaned, they are not often used in the pharmaceutical or food and beverage industries.
MSS SP-110-2010 (INCLUDES ERRATA) - Ball Valves Threaded, Socket-Welding, SolderJoint, Grooved and Flared Ends (includes errata sheet) and MSS SP-72-2010A - Ball Valves with Flanged or Butt-Welding Ends for General Service specify guidelines for the manufacturing of ball valves through a variety of welding and connecting methods. Guidelines for ball valves designed out of plastic materials compatible with the pipe system’s fluid are covered in MSS SP-122-2012 - Plastic Industrial Ball Valves. MSS ball valve guidelines also cover specific industry manufacturing and use of ball valves, such as in MSS SP-145-2013 - Metal Ball Valves for Low Pressure/Low Temperature Plumbing Applications.
Like ball valves, butterfly valves have short operation time because they use a valving element that simply rotates on a quarter turn to open or close the passageway through which fluids travel. For butterfly valves, this element is a disc that is held in place in the center of the valve by a rod. Butterfly valves are characterized by their simple construction and compact design, and, despite having limits for use at certain temperatures, they are often used in applications for air and water.
MSS SP-67-2011 - Butterfly Valves covers a wide breadth of standard practices and specifications of different components of butterfly valves and related testing procedures and design requirements. In addition, to confront the challenges that come with high-pressure butterfly valves, MSS SP-68-2011 - High Pressure Butterfly Valves with Offset Design provides guidance.
Gate valves, as their name implies, function by lifting a rectangular or circular gate in and out of the path of the fluid. This valve is generally suited for on/off liquid service.
There is a wide range of variation among the different types of gate valves. For example, knife gate valves, which are used to cut through incredibly thick fluids and dry bulk solids need unique specifications that keep the valve self-cleaning and functioning properly. These include MSS SP-135-2016 - High Pressure Knife Gate Valves and MSS SP-148-2014 - Low Pressure Flanged or Lugged Carbon Steel and Iron or Ductile Iron, Cast or Fabricated, Bonnetless, Knife Gate Valves without Liners. Gate valves also have stems, which indicate the valve position, and can either be rising, as addressed in MSS SP-121-2006 - Qualification Testing Methods for Stem Packing for Rising Stem Steel Valves, or nonrising. In addition, some gate valves also have bonnets, which prevent the occurrence of leaks. These are addressed in ANSI/MSS SP-144-2013 - Pressure Seal Bonnet Valves.
Because of their immense variation, gate valves have applications in a variety of industries. For example, knife gate valves are often used to manage petroleum and crude oil.
A diaphragmvalve uses a diaphragm to isolate or block flow, and, because the material of the membrane can chemically degrade, diaphragm valves are used under the conditions of low pressure and a limited temperature operating range. It is important that users are aware of the physical limitations of the diaphragm membrane and restrict the operating temperature and pressure. These valves can regulate most gases and liquids, but they require frequent maintenance.
Valve Actuators, Pipe Fittings, Flanges, Associated Seals
In addition to these four examples, MSS has a variety of standards documents giving specifications and standard dimension requirements for many other types of valves. However, the focus of MSS is not just limited to valves, but concentrates on the manufacturing of the different connective and regulative components of pipes. These standards can be downloaded from the ANSI Webstore.