Valves Are Everywhere

MSS Valves

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.

Manufacturers 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.

Ball Valves

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.

Ball Valve Standards

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.

Butterfly Valves

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

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.

Gate Valve Standards

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.

Diaphragm Valves

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.

MSS SP-88-2015 - Diaphragm Valves outlines the limitations of valves using a nonmetal diaphragm to separate the working parts of the valve from the line fluid. These guidelines are for the different variants of resilient diaphragm valves, and provide the means to reduce the necessary lifetime 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.

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  1. The reason the valve doesn’t properly turn off, as shown by the closing mechanism as shown in the picture (4) is because, as the gate valve gets older, you will find that the dirt or scale will built up, which stops the closing mechanism from correctly shutting. The way that is best to solve this is to either clean the valve out completely or to replace the gate valve.