J-tube Supports

Additional seabed support is often required to avoid excessive stress on a riser or umbilical at the point where it exits the j-tube.

We provide dedicated J-Tube Support Formwork designed to reduce installation time and provide even support along the riser bend.

Our formworks features include:

Wide base for enhanced soil bearing and reduced settlement
Formwork shoulders to constrain and shield flowlines and umbilicals
Optional scour mitigation skirts
Optional heavy density grouts for outstanding stability performance in current environmentsMore information is available on our fabric formwork product page.

FAQ’s

Are the supports pre or post installed?

Our custom J-Tube support bags can either be pre installed on a deployment beam prior to the umbilical pull-in or post installed after pull in.

Depending on the available space for the ROV to work, Subcon can tailor an installation method to suit your needs.

Do the supports offer any further functionality?

Subcon’s bespoke supports can be designed with elevated shoulders that protect the umbilical from accelerated water velocities at the base of the structure.

This reduces the fatigue in the umbilical in its overall design life.

Are there any restrictions on size of the J-Tube support?

Our grouted J-Tube supports are custom designed for each application so can be designed with consideration to surrounding infrastructure and seabed configureation.

Is on-bottom stability an issue for the J-Tube supports?

As water particle velocities are accelerated around the base of offshore structures, the overall stability of the support may be compromised. Subcon has proprietary heavy density grouts that can be pumped into the support formworks to ensure stability throughout its design life.