Siemens Subsea Products


“Siemens produce complicated parts in high quality material and each part can be completely different. We developed a system that can take CAD model data and import it into the machine and produce each component correct first time.”

Mark Gerard Senior Software Engineer

Programmable Tube Bender Uses Constant Torque To Create Stress-Free Parts


Siemens Subsea Products (SSP) is a leading manufacturer of subsea equipment for offshore oil and gas applications. Many of its products, such as the renowned Bennex Anguila range of ‘cobra’ heads that terminate umbilicals on subsea equipment, use rigid small-bore tubes to convey hydraulic fluid for power and control purposes. These tubes are fabricated from expensive corrosion-resistant alloys and involve complex precision bends, with tight process control to avoid mechanically stressing the material.

Until recently, SSP fabricated some tubes in-house, using manual bending techniques, but met about 50 to 60% of its needs using expensive bought-in preformed parts. The company therefore decided to improve manufacturing efficiency by automating its tube bending operations, favouring all-electric technology for its programmability, accuracy and repeatability.

Following recommendation from a customer, SSP sought Unison’s help to develop a machine for the task. Most tubes are produced in very small batches, making fast tool changeover important, using hard alloys such as Inconel and Duplex/Super Duplex stainless steel. They are typically one to three metres long, with outside diameters of 3/8 to 5/8 inch and a 3 mm wall thickness.



The tube bender developed for SSP is based on a 25 mm Unison Breeze machine, networked to an Inventor 3D CAD system. It incorporates a ‘rise and fall’ pressure die for right- and left-handed bending, allowing tubes with multiple complex precision bends to be produced in one continuous cycle. The machine accommodates an inter-bend space of just 5 mm to facilitate production of parts for space constrained applications such as cobra heads; with manual bending this was limited to 20 mm. The machine’s use of software-controlled servomotors also allows constant torque to be applied throughout the bending process to prevent material stresses, which is very difficult to achieve manually.


SSP now produces all tube parts in-house. Improved manufacturing flexibility is only part of the story. Other advantages include:

  • Fully automated right-first-time manufacturing
  • Repeatable process with sub-millimetre bend accuracy
  • Scrap from in-house tube bending reduced by more than 90%
  • All tube parts now fabricated from CAD-derived data
  • Proven machine payback time of less than a year
  • Major reduction in skilled labor requirements
  • Spare production capacity for third-party bending.

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