API 6DSS Subsea Ball Valve Buyer’s Guide


Total announced in 2020 it was preparing to drill an offshore well at a record water depth of more than 3.6 meters. As the demands of subsea production increase, you need valves that can perform under these severe conditions.

As water depth increases, water pressure also increases. Valves must withstand this pressure. They must perform reliably to control the process fluid without letting the fluid leak or seawater enter.

In addition, specialized boats and personnel are necessary for any repairs or maintenance. Valves must perform maintenance-free for years. They must withstand a variety of media, such as hydrocarbons, seawater, and injection chemicals.

An API 6DSS subsea ball valve has many advantages for subsea applications. Learn more about API 6DSS subsea ball valves and how to choose the right valve for your system.

Benefits of Ball Valves for Subsea Applications

Isolation or on-off valves are some of the most common in subsea applications. Ball and gate valves are two common choices. Ball valves have several benefits in subsea pipeline systems.

Ball valves have a more compact design than gate valves. They can be smaller and lighter.

Ball valves have a low pressure drop and a high flow capacity. These features make them a high recovery valve. They’re efficient to operate.

Ball valves are simpler than other types of valves. They require less maintenance. When repairs and ball valve maintenance are necessary, the process is straightforward.

Ball valves are very robust. They can withstand high pressure. They’re available in a range of materials suited for subsea applications.

What Is API Spec 6DSS?

API Specification 6DSS defines requirements for valves in subsea petroleum and natural gas pipelines. The American Petroleum Institute (API) released the most current version of Spec 6DSS in 2017.

API Spec 6DSS is essentially the same as ISO 14723. It refers to other relevant ISO and ASME standards, like ISO 13623 on pipeline systems. API Spec 6DSS covers the entire valve production process, which includes:

  • Design
  • Manufacturing
  • Quality control
  • Assembly
  • Testing
  • Documentation

The standard covers several types of valves, such as:

  • Ball
  • Check
  • Gate
  • Plug
  • Axial on-off

It covers ASME Class 150, 300 600, 900, 1500, and 2500 valves. It doesn’t apply to valves with pressure ratings beyond Class 2500.

How to Choose an API 6DSS Subsea Ball Valve

You know that an API 6DSS ball valve will meet the basic requirements for subsea pipeline systems. You have several choices to make, though, to find the right valve for your application.

Size, Pressure, and Temperature Requirements

Your subsea ball valve must be able to handle the media in your application. It needs to be large enough for the flow rate.

The valve needs to withstand the minimum and maximum pressure of the subsea pipeline system. The material of the housing is a key factor in the valve’s pressure range.

The valve also needs to handle the minimum and maximum operating temperatures of your system. The housing and seal materials are the main determining factors for a valve’s temperature range.


A subsea ball valve must withstand a variety of corrosive fluids. Factors to consider include:

  • Produced and injected fluids that will contact the valve
  • Service temperatures
  • Operating pressure ranges
  • Possible galvanic effects from the contact of dissimilar metals
  • Crevice corrosion at seal and flange faces
  • Weldability

Metals are the best choice for the valve body and components like bolts. Other parts like the seats are frequently made from thermoplastic.

Metals for Subsea Ball Valves

Several metals are options for the valve body. Stainless steels such as 410 and F6NM have good corrosion resistance. They need a weld overlay with corrosion-resistant alloy to minimize pitting in subsea environments, though.

Duplex stainless steel also has good corrosion resistance. They combine features of austenitic and ferritic stainless steel. Super duplex grades have even higher corrosion resistance.

For the most severe environments, nickel-based alloys can be a good option. Nickel alloys have excellent corrosion resistance. They’re usually a more expensive choice, though.

Thermoplastic Options for Ball Valves

Thermoplastics can be a good choice for ball valve seats, packing, and shaft seals. They provide excellent resistance to chemicals, heat, and abrasion.

PEEK (polyetheretherketone) is a common choice for ball valve seats. PEEK is tough and durable. It retains these properties in high-pressure, high-temperature environments.

PTFE (polytetrafluoroethylene) is an option for the shaft seal and stem packing. It has a low coefficient of friction and low moisture absorption. It remains flexible at low temperatures.

Floating or Trunnion Design

Options for ball valves include floating or trunnion design. In a floating ball valve, the ball is attached to the valve body through the stem. Pressure from the media forces the ball into the downstream seat to make a tight seal.

The ball in a trunnion ball valve is connected to the valve body through the stem and a bottom shaft. The ball doesn’t move downstream with the pressure of the media. Trunnion valves can maintain a tight seal on both sides at the same time.

Trunnion valves are effective for high- and low-pressure applications. They require less torque than floating ball valves. However, they’re a more expensive option.

Type of Operator

The options for subsea ball valve operators depend on the depth of the water. Manual operation by a diver is possible for shallow water applications.

For deep water systems, electric and hydraulic actuators are possibilities. These valves can use remote actuation or actuation by a Remotely Operated Vehicle (ROV).

Finding the Right Ball Valve Provider for Subsea Applications

Choosing the right API 6DSS subsea ball valve is critical for the safety and performance of your pipeline system. The valve must meet the requirements of your project. It also needs to fit into your ball valve budget.

The right ball valve provider can help you find the best valve for your application. We have an extensive inventory, OEM support, and expert logistics. We can design a customized solution to meet your needs.

Contact us today for more information about how our API 6DSS subsea ball valves can support your project.