In the industrial sector, the American Petroleum Institute (API) has established numerous standards for valves to ensure consistency and quality control in valve design, manufacturing, and application. This article briefly discusses several common API valve standards, including API 600, API 602, API 603, API 623, and more, explaining their applications for different types of valves.
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Using standards in engineering datasheets is critical. API standards ensure consistency in requirements between valve manufacturers and users, such as material selection, body thickness, and stem diameter. For example, when sourcing raw materials from different China steel suppliers, unified API standards help guarantee that the steel meets the same quality and performance requirements regardless of the supplier. Without unified standards, suppliers might use varying specifications, resulting in differences in quality and performance. Therefore, API standards help engineers and manufacturers maintain consistency in valve design and usage.
API 600: API 600 is designed for heavy-duty applications, with a thicker valve body suitable for pressure ratings from 150 to psi. These valves, built with higher thickness than ASME B16.34 (Valve Flange Rating Standard), are intended for demanding industrial environments.
API 603: API 603 offers a lightweight valve standard with a body thickness smaller than API 600, comparable to ASME B16.34. It’s primarily used in lower-pressure environments and provides higher corrosion resistance, making it popular in many industrial and commercial facilities.
API 602: Situated between API 600 and API 603, API 602 applies to small-diameter valves, generally between 1/2 inch and 2 inches, with an 800 psi pressure rating. Its compact design is ideal for small valve applications, often found in narrow piping systems.
Due to the special needs of globe valves in controlling flow, API 623 came into being. API 623 focuses on the thickness, stem diameter and pressure resistance of globe valves to meet the requirements for higher thrust. Especially in high-pressure environments, the API 623 globe valve standard ensures that the valve can withstand higher stresses, making it more stable in flow control applications.
API 623 also draws on many advantages of API 600 and adds a material classification table for control valves to help engineers choose the right material according to application requirements.
ASME B16.34 covers pressure-temperature ratings, dimensions, and testing for valves.
API 600 focuses on steel gate valves for petroleum and natural gas industries, specifying design, materials, and testing.
Although they have overlapping areas, ASME B16.34 is broader for all valve types, while API 600 is more specialized.
For engineers and procurement managers, knowing when to use each is key for compliance and performance.
API 609 is the main standard for butterfly valves. divided into Class A and Class B based on application pressure and environment:
Class A butterfly valves: Suitable for low pressure, non-critical applications and concentric design. These valves use the manufacturer's cold rated pressure and are used in simple applications at a lower cost.
Class B butterfly valves: Suitable for harsh applications with high corrosion and high pressure, and meet ASME 16.5 and 16.47 flange rating standards.
Class B butterfly valves have double and triple offset designs, which can provide excellent sealing performance and are more stable and reliable in high performance and harsh environments, but the cost is higher.
API 608 is specifically for ball valves, with two primary designs:
Floating Ball Valve: A floating ball rests on the valve seat, typically used in medium to low-pressure applications. The fluid flow moves the ball, and the seat holds the ball in place within the valve body. This simple design is cost-effective.
Trunnion Ball Valve: The ball is fixed by specific mounts, ideal for high-pressure applications. Since the ball doesn’t shift under pressure, this design offers better stability and durability in high-pressure conditions.
API 599 and API 594 set the primary standards for plug and check valves, respectively.
API 599 covers plug valve designs for a wide range of applications, with valve sizes from 1/2 inch to 36 inches. API 594 is the main standard for check valves, ensuring they provide one-way flow in systems and prevent backflow.
ASME B16.34 is a comprehensive standard covering pressure–temperature ratings, dimensions, materials, and testing for valves in general industrial use.
API 600 is a standard specifically for steel gate valves used in petroleum and natural gas industries, focusing on design, materials, and quality requirements.
These two standards are widely recognized across oil & gas, water treatment, and industrial engineering projects.
ASME B16.34 provides the baseline requirements for most valves, while API 600 is a specialized guideline for gate valves in demanding applications.
The key difference lies in scope and application:
ASME B16.34 applies to all valve types, covering dimensions, materials, and pressure ratings.
API 600 focuses only on steel gate valves and sets stricter requirements for wall thickness, sealing, and durability.
If your project involves general industrial valves, follow ASME B16.34.
If you are specifying steel gate valves for oil, gas, or high-pressure applications, follow API 600.
Many engineering specifications require compliance with both standards to ensure safety and reliability.
Yes. Many gate valves are designed to comply with both standards.
They follow ASME B16.34 for dimensional and pressure requirements, and API 600 for gate valve–specific design and testing.
In water and wastewater treatment, these standards may be referenced for material quality and testing requirements, especially in projects with high-pressure or corrosive service conditions.
However, local specifications and project requirements should always be reviewed.
In the valve sector, different API standards are applied to various valve types and applications. Below is a summary of each API standard and its applications:
API 600: Heavy-duty gate valve standard for high-pressure environments.
API 603: Lightweight gate valve standard for low to medium pressure with corrosion resistance.
API 602: Small-diameter gate valve standard for narrow piping systems.
API 623: Control valve standard, meeting high-thrust demands for globe valve applications.
API 609: Butterfly valve standard, with Class A (low-pressure, non-critical) and Class B (high-pressure, corrosive) classifications.
API 608: Ball valve standard, encompassing floating and trunnion ball designs.
API 599 and API 594: Primary standards for plug and check valves, respectively.
As industry demands and technology evolve, API standards will continue to be updated, ensuring valve reliability and safety across various environments.
Union Valve, a specialized butterfly valve manufacturer in China, provides custom designs to meet precise specifications. Their products comply with a range of international standards, including GB, BS, GOST, DIN, API, and ANSI. For more information, please contact us.
Introduction:
I’m fully aware that there are already many check-lists for valve selection available on the market. Some of them quite simple and unfortunately also incomplete, others are so complicated that a “normal brained” person like me has trouble understanding the whole picture.
Through the years, and working in different valve-application fields such as Oil & Gas, Power Generation and Waterworks, I have built up my own check-list. It covers all the most important points to be considered when selecting on-off valves. I tried to include some personal experiences, tips and external links that might help to reduce mistakes while selecting valves.
Nothing really new for the experienced valve specialists out there, but maybe a real help for any “Newbie” getting involved in the valves selection process.
Kindly take a special attention to the "TIPS" sections. I offer here a real added-value information based on my own experience.
Enjoy reading and don't hesitate to give any feedback, additional information or clarification.
With humble regards
Michel F. Bolle - 17.7.
1 ) Applicable main standard – DIN (EN)/ASME and/or others?
While often forgotten, this is one of the most important points to clarify in the valve selection process. There are two main standards on the valves market EN (European) and ASME (American).
Depending on the location where a plant is built or located one or the other standard might be used. Usually, this information can be found in the technical specification of a project.
Other standards might be applicable such as GHOST (Russian) or AWWA (Amercian Water Works Association) among many others. In the EU, for example, most valves fall under PED standard requirements. So it would be impossible to install I the EU, a big size high-pressure gate valve made in the USA without CE marking and the related PED approval.
TIPS:
According to EN standards pressure class indication is given in PN and size in DN, while according to American standards we speak about #(lbs) for pressure class and “ (Inches) for the size. When working on a new project, or a replacement project to not take this as a rule. A Valve specified as DN 400 and PN100 does not necessarily mean it is according to EN standards. There is a lot of confusion on the market, people mix up EN & ASME and there also many “hybrid”(mix of standards) valves on the market. Better check twice!
2) Type of Valve?
The type of valve needed is usually given by the process and the main function of the valve. Do we want to use the valve only for isolation (on-off) or do we need to control a certain flow? Might the valve be used to prevent back-flow or as a safety valve? Do we need a valve for steam (most likely a gate valve for isolation) or for water (most likely a Butterfly Valve).
Another important point de define from the beginning is to decide if you need a valve that seals in both directions (Ex. soft seated centric butterfly valve), or a valve that needs to seal only in one direction (Ex. double eccentric butterfly valve)
If working on replacement projects the choice is quite easy as usually the existing valves are replaced by the same type.
TIPS :
A very good source for information about different types of valves and their applications are the catalogues of the valve manufacturers. Usually, they state the main applications for each type of valve. Example: “Gate / Globe Valves excellent for Steam”
3) Size of Valve?
Usually, a valve is mounted in a piping system where the size of the pipe is already given. In this case, it is quite easy as the size of the valve will be the same as the piping size. Nevertheless, there are some factors which can influence the choice of the size of the valve such as:
- Max Allowable pressure drop (if any)
- Max Flow rate (if any)
While defining the size of the valve, these two factors have to be considered. There are some exceptional cases where the size of the valve might be bigger than the pipe size or smaller (which can be an important costs saving factor).
TIPS :
Consider that for many valve types such as globe valves or Ball Valves there are two options available on the market; Full Bore or Regular Bore (Reduced bore). In order to choose the right one, it is important to know if there is any requirement for max allowable pressure drop?
As an example: If you have a valve at a bottom of a pipe just to drain water, the pressure drop might not be so important and you can use a reduced bore valve. On the other hand having a valve in a steam system that brings steam to a turbine, pressure drop requirements might be crucial for the performance of the turbine.
Want more information on DIN Standard Globe Valve? Feel free to contact us.
4) Pressure Class?
In many cases, the pressure class for a valve is already given by the pressure class of the defined piping system.
Otherwise, the pressure class of a valve is the result of the combination of Pressure, Temperature and main body/bonnet materials used.
Here is a great example of a table for pressure classes definition according to ASME B16.34 (Source: Globalsupplyline):
http://globalsupplyline.com.au/wp-content/uploads//10/Valve_Material_Temperature.pdf
TIPS:
In order to define the right pressure class it is very important to know the “design” pressure & temperature for the piping system. If you define a pressure class according to “operating” conditions your selected valve might not withstand the “worst case” scenario.
5) Body/Bonnet Material?
The choice of the material of construction of the main parts (body/bonnet) of your valves depends on the medium. It is part of the job of the valves specifying engineer to check first material compatibility (resistance) with the medium (gas, steam, fluide, etc). In addition to this the design conditions of the piping system have to be considered (for example castings in WCB has a limit of temperature at 425C)
If the material of the piping system has already been defined, then you are lucky, as for the valve you can choose the same grade material.
TIPS :
Do not forget that the ambient conditions, can also be an important factor for the choice of the valve material. While A105 carbon steel might be a great material to be used in central Europe for a globe valve , in Russia (due to the low winter temperatures) you might have to use LF2 material instead of A105. Very salty ambient conditions might let you choose Aluminium Bronze as Valve Body Material instead of Stainless Steel.
6) TRIM Materials?
The choice of trim (stem/seat/disc or ball) materials are most likely to be in line with the chosen body/bonnet materials and will depend also on the medium, design conditions, as well on the leakage rate we want to reach.
While speaking about the trim, here should also be included the choice of all sealing material directly connected to the trim (Ex : Gaskets, Packings, etc)
Other factors to consider are who often a valve is used and for how long it should last. Depending on this we might choose a higher grade for trim materials
TIPS:
If there is the possibility of having a vacuum condition while the valve is in service trim materials & design might have to be different (Example : Lantern ring on gatevalve packings)
Widely used on the market is the API Trim chart. Here you find a useful link:
https://blog.projectmaterials.com/valves/api-trim-chart/
7) Leakage Rate (valve testing)?
Directly related to trim, but often forgotten is the “maximum allowable leakage rate”. There might be some applications where this is not important, but when we start talking about this requirement, it gets quite tricky and we need to be sure which standard is applicable. Checking the questions of the leakage rate will also end-up by defining the applicable valve testing standard.
Here is an excellent overview and explanation of the different standards:
http://globalsupplyline.com.au/wp-content/uploads//10/Valve_Leakage_Rates_Test_Std.pdf
TIPS :
The definition of “0” leakage doesn’t mean anything by itself and is often confused with “Bubble tight”… Always check which is the applicable standard for the maximum allowable leakage rate.
8) Connections?
The most commonly used connections for valves are ; screwed (Ex : NPT or Gaz), welded (SW or BW) or Flanged.
Usually, the choice of the of the connection is given by the philosophy of the whole piping system. Safety and emission aspects might also be considered, as well as how the maintenance should be done.
Consider also that in any case the valve connection must match 100% the pipe connection.
TIPS :
Out of experience there are some general market tendencies of the use of end-connections:
- Power Plant Steam Systems : Welded (un to 2” SW, larger BW)
- Raffineries : Flanged
- Gas Systems : Welded
- House heating systems : Screwed
- Water distribution / wastewater : Flanged
9) Actuation
Once we have defined our valve, we need to figure out how we want to operate it. The most common ways to actuate a valve are:
- Hand actuated (lever / Hand wheel)
- Electric Actuator
- Pneumatic Actuator
- Hydraulic Actuator
- Self Actuated (by the medium)
TIPS:
Consider that for electric actuators the voltages are different depending of the location of the installation. This has to be checked absolutely when defining the actuator. Sizes of hydraulic and pneumatic actuators depend on available min air or oil pressure.
10) Painting
One out of two NCR’s for valves I have seen in the past 20 years have been related to painting.
For many projects, there are available painting specifications and/or colour codes. The choice of painting can depend on many things such as temperature resistance (medium & ambience), location, colour codes, required painting thickness et….
While often forgotten in the selection process of valves, it is a key element.
TIPS:
While usually stainless steel or aluminum bronze valves would be supplied unpainted, there are some installations that use piping color codes these valves might also be painted. Better check twice.
Other points to consider for the selection of valves:
- Accessories (limit switches, solenoid valves, lantern rings)
- Noise
- Emission
- Weight
- Dimensions
- Installation (for example horizontal or vertical)
Valve selection can be quite tricky, but it must not be. Following a simple check-list ensuring that during the selection process all the important key-points are considered is a good step in the right direction.
If you are missing some knowledge somewhere, let’s say “material resistance” speak to your trusted valve partner. According to my experience valve manufacturers are always willing to advise.
Last but not least, consider that the time used to make the right valve selection is a very smart investment! A lot of valve problems on production sites are due to poor and wrong valve selection.
Feel free to comment and share this article. Improvements are very welcome.
Michel F. Bolle - Industrial Valve Expert - 17.7.
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