A guide to the MSS standard for valves

Brief guide to US MSS standards for industrial valves

As we have seen in a recent article, there are different types of industrial valves. Mechanical systems designed to control and regulate the flow of a fluid may vary depending on the valve mechanism, the type of fluid to be controlled and the needs of the fluid. Depending on the type, they can then have not only purposes but also different industrial applications.

But there is another important factor to consider when choosing the perfect industrial valve for your application and it is the compliance with certain construction standards.

Because many industrial sectors and production processes require precise and effective valves, even in heavy environments or mission critical situations, several organizations set specific standards to be respected in the construction of these valves, so that they ensure a recognised "standard" level of quality.

But what are the standards, how do they differ? And what valve characteristics do they regulate? In this short guide we find out how the standards for industrial valves work and, in particular, what the US standard MSS is about.

What are standards?

When engineers have to specify valves for use in a new production plant, or when they have to order replacements and spare parts, they are faced with a complex panorama of codes and standards. In fact, not all industrial valves are the same: they differ not only in terms of materials and types, but also in terms of the standards to which they conform.

Dealing with critical flow control, pressure regulation and stringent safety regulations, it is important that valves are suitable.

But what do the standards cover? They provide clear and consistent specifications for:

construction materials;
validation of the project through testing;
quality control in production;
appropriate applications and compatibility.

Each aspect is regulated by one or more codes, whose compliance ensures that the valves provide reliable fluid flows in various industrial contexts, from energy to production, while managing even extreme pressures and temperatures.
Thanks to the standards, engineers and valve purchasers can navigate effectively through these specifications to choose the right valves for different system requirements. Choosing the wrong standard carries the risk of poor performance or even dangerous failures.

Who sets the standards?

The question therefore inevitably arises, for those less familiar with the world of industrial valves: but who defines these standards? It is not just one actor, but a multiplicity of national bodies. Some of these are only valid at national level (and the most important ones are generally those in the US, in addition to the British BS-EN) while others protect them at global level.

The main standardisation bodies are generally considered to be:

ANSI (American National Standards Institute), oversees and regulates inter-sector standardisation for the US market. Its standards provide the basic specifications for valves for materials, tests and installations aligned with US production and supply chains. ANSI also adopts other international standards if relevant in the US market. MSS is a member of ANSI
API (American Petroleum Institute) identifies several specific standards for valves used in oil, gas and petrochemical applications - the Oil & Gas sector. Given the importance of the sector and the often burdensome conditions of use, these strict codes are also recognised globally. Adherence to API specifications ensures valves give safe control of high-pressure fluids and hydrocarbons as they travel through structures such as pipelines, refineries, offshore platforms and other infrastructure
ASME (American Society of Mechanical Engineers) drafts and develops construction codes for pressure vessels and associated piping systems in all sectors. Their adherence ensures that valve materials, production methods, tests and installations meet the criteria for handling high temperature fluids and pressure loads without failure.
ISO, the International Organization for Standardization, is perhaps the most globally famous and publishes codes adopted by over 165 national standards bodies. These provide a common framework for technical specifications at global level.

The MSS standard

As we have seen, in the institutional system of the United States there are various standards that can be used to specify the industrial valve, mainly depending on its application. This includes the MSS SP (Standards Society of Valve and Fitting Manufacturers).

The company is a member of ANSI and, as their website states, "is a non-profit technical association organized for the development and improvement of codes and industrial, national and international standards related to the valve and fittings sector."

The main purpose of MSS is to provide the means for developing standard engineering practices for the use and benefit of industry and users of its products, such as industrial valves.

The standards drawn up by MSS are manifold and cover a wide range of requirements specific to materials, valve types, processes, tests, applications. This link provides a complete list, but just to give an idea of their variety and comprehensiveness, we can mention:

MSS SP-6, standard for the contact faces of valve pipe flanges and fittings
MSS SP-9, spot coating for bronze, iron and steel flanges
MSS SP-25, standard marking system for valves, fittings, flanges and nozzles
MSS SP-42, Class 150 Corrosion Resistant Gate, Globe, Angle and Check Valves with Flanged Ends and Butt Welds
MSS SP-55, Quality standard for steel castings for valves, flanges and fittings and other piping components
MSS SP-84, steel valves with beaker welding and threaded ends
MSS SP-86, metric data in the standards for valves, flanges and fittings

But the standards drawn up by MSS are still varied and numerous, covering many aspects of the production and use of industrial valves.

ECI valves: safe solutions in compliance with MSS standards

ECI is specialized in the production of industrial valves for oil, water and gas. These systems guarantee high performance and versatility in every operational context, designed and built with carefully selected materials such as brass, bronze and cast iron to ensure a great resistance to corrosion, pressure and high temperatures - Compliance with several international standards, including MSS.

Due to the wide range of valves available, these can be used in different sectors and areas, including heating, ventilation and air conditioning systems, but also Oil & Gas. Each product is tested and monitored to ensure the highest quality standards. The company produces both bronze and cast iron valves in two types of standards, one is the American standard "MSS-SP" and the British "BS-EN".

As a manufacturer of valves for different industrial sectors, ECI offers various types of valves, made according to the MSS standards, including:

bronze globe valve BR42 according to MSS standard SP-80
Bronze ball valve BR120 conforms to MSS standard SP-110
Bronze check valve BR125 according to standard MSS-SP-80
Spheroidal cast iron butterfly valve G103, compliant with MSS standard SP-67
Cast iron gate valve G501, standard MSS SP-70

And many others, both in cast iron and bronze and for different types of valves.

Dealing with the different and varied valve standards can seem complicated even for experienced engineers or plant managers, but they need to specify hundreds of valves. However, unified codes ensure that valves will provide reliable and watertight performance while safely handling fluids for decades.

No problem if you need it: consult the ECI valve experts team to interpret the specifications in line with system requirements. With extensive experience in valve manufacturing and standardisation, the ECI team is always ready to guide you in choosing the appropriate valve. Contact our application engineers today to determine the right valves for your next project.

For more information on ECI’s MSS standard valves or to get advice on the right product for your production needs, please contact us!