The subsea end of an electrical cable, optical fiber, thermoplastic hose, or metallic tube may be terminated in half a connector assembly, which can then be mated underwater. Alternatively, the umbilical components may be terminated directly into a subsea control pod or junction box. The design of umbilical terminations and ancillary equipment is invariably specific to a particular umbilical system and, as such, detailed specification data are the scope of ISO 13628-5 [2].

Umbilical Termination Assembly

A topside umbilical termination assembly (TUTA) is designed for dynamic umbilicals. A TUTA provides a termination point for the tubes, wires, and optical fibers from the bull nose assembly with stainless steel tube-to-tube fitting connections. The TUTA assembly includes an electrical junction box for interfacing with the electrical wire and an optical junction box for interfacing with the fiber optic filaments from the bull nose assembly. The metal tubes route to hydraulic couplers via super duplex steel tube pigtails and tube sockets where they are welded. Each set of electrical wires and fiber optic filaments is terminated with the female half of an electrical or optical connector that can be mated underwater.

Bend Restrictor/Limiter

It is usually used where the umbilical is attached to the umbilical subsea termination point.

Bend Restrictor

Pull-In Head

A pull-in head is used to pull the umbilical along the seabed or through an I- or J-tube. The pull-in head is designed to withstand installation loads without damage to the umbilical or its functional components. The pull-in head is designed, if possible, to allow uninterrupted travel over rollers/ sheaves and through I- or J-tube risers without damaging or snagging.

Hang-Off Device

The hang-off device is used for supporting the umbilical to the top of the I-tube or J-tube at the host suspension point. The hang-off point will be on a deck or outboard of the columns in the tubes.

Bend Stiffer

The bend stiffer is a device for limiting the bending radius of the umbilical by providing a localized increase in bending stiffness. It is usually a olded device.

Electrical Distribution Unit (EDU)

The EDU is an oil-filled and pressure-compensated enclosure, within which the incoming
Hang-Off Assemblies
electrical power and electrical signals are distributed to two or more atellite SCMs. More than one EDU may be chained together, with each EDU serving a number of satellite SCMs.

Weak Link

A weak link is a device used to protect equipment that is permanently installed on a manifold or template, so that in the event of an umbilical being snagged, the umbilical will break away, activating the link and shearing jumpers connecting to the fixed subsea equipment.

Splice/Repair Kit

A splice/repair kit should be provided to contain the necessary materials and parts to perform repairs on both the main dynamic umbilical and its components and the in-field static umbilical and its components in the event that it should become damaged during the installation process.

Carousel and Reel

Any reel used is not allowed to violate the MBR of the stored umbilical.
Bend Stiffer

Joint Box

A joint box is used to join umbilical sublengths to achieve overall length requirements or to repair a damaged umbilical. Each umbilical end to be joined has an armored termination, if applied. The joint box is of a streamlined design, with a bend stiffer at each end if required, and of compact size to facilitate reeling storage and installation requirements.

Buoyancy Attachments

Example of a Large Umbilical Termination Assembly with a Large EDU Included

Depending on the installed configuration, a dynamic umbilical can necessitate buoyancy attachments in the form of collars, tanks, etc., to achieve the necessary configuration and dynamic motions. The method of attachment does not induce stress cracking in the umbilical sheath, nor allow xcessive stress relaxation within the compressive zone of the attachment if clamped, nor allow excessive strain of the umbilical and its component.


[1] R.C. Swanson, V.S. Rao, C.G. Langner, G. Venkataraman, Metal Tube Umbilicals- Deepwater and Dynamic Considerations, OTC 7713, Offshore echnology Conference, Houston, Texas, 1995.

[2] International Standards Organization, Petroleum and Natural Gas Industries, Design and Operation of Subsea Production Systems, Part 5: Subsea Umbilicals, ISO 13628-5, (2009).

[3] Technip Technology and Teamwork Achieve World Class Success for Shell Perdido, Oil & Gas Journal on line, Volume 108 (Issue 31) (April 1, 010). index.

[4] N. Terdre, Nexans Looking beyond Na Kika to Next Generation of Ultra-deep Umbilicals, Offshore, Volume 64, Issue 3, Mar 1, 2004, ttp://www.offshore-mag. com/index.

[5] O. Heggdal, Integrated Production Umbilical (IPU for the Fram Ost (20 km Tie- Back) Qualification and Testing, Deep Offshore Technology onference and Exhibition (DOT), New Orleans, Louisiana, 2004, December.

[6] Det Norske Veritas, Submarine Pipeline Systems, DNV-OS-F101, (2007).

[7] Det Norske Veritas, Fatigue Strength Analysis of Offshore Steel Structures, DNV-RPC203 (2010).

[8] J. Hoffman, W. Dupont, B. Reynolds, A Fatigue-Life Prediction Model for Metallic Tube Umbilicals, OTC 13203 (2001).

[9] W.K. Kavanagh, K. Doynov, D. Gallagher, Y. Bai, The Effect of Tube Friction on the Fatigue Life of Steel Tube Umbilical RisersdNew Approaches to Evaluating Fatigue Life using Enhanced Nonlinear Time Domain Methods,