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Replace a single ball valve by a Double Block & Bleed

When creating the design specification for our Taurus Series we came along the point ‘face to face’ dimensions. Immediately some colleague said “ASME B16.10 and EN 558 – but same length as a single ball valves for the Taurus DBB with 2 balls and a bleed in between?”

Well, we discussed that there might be a possibility to achieve this goal and we listed some values and benefits we could offer to our customers with such a short face to face dimension:

The major benefit would be that the new Double Block & Bleed (DBB) Pipeline Ball Valve (Taurus-Series) has the same face-to-face dimension as a single block ball valve. The length of a single block ball valve is specified in ASME B16.10 and APl 6D. As a consequence the valve can easily be installed into an existing pipeline without the need for any re-work on the pipeline.

The Customer then has the possibility to exchange an already installed single ball valve with a Double Block & Bleed valve without taking care of all the action which is necessary to adjust the distance between the two flanges of the pipeline.


Please consider the following situation: Due to increased safety requirements you get the task to change all single ball valves in a specific application to a Double Block & Bleed Ball Valve.

Presumably your first thoughts are “Oh my gosh, how many flange connections are affected! – Disconnecting the pipeline flange, shorten the pipe, prepare the weld seam, welding the new flange on the new position, testing the weld seam, doing the painting.”

Good to know, that there are DBB’s with ASME B16.10 face-to-face dimension available on the market.

Beside this main benefit, there are others which correspond with the short length:

  • saving space when planning a new piping.
  • reducing weight, especially on ships or off-shore application
  • Saving costs, especially for exotic materials like Alloy 625 or similar.

Seeing those benefits for our customers, we realized that we had to specify the ASME B16.10 dimension wherever possible in our “design specification”.

Today we can say that for our Taurus 2 piece design we can offer the ASME B16.10 length for most of the sizes – without using tapped flange connections:

  • Floating Ball Design Class 600, 900 & 1,500
  • Trunnion Ball Design Class 900, 1,500

(Image source: © AS-Schneider)