Jumper hose: nodule transport as flexible pipes

The jumper hose line provides a flexible connection between the vertical riser system and the mining vehicle with the sole purpose of transporting the mined ores in slurry form. It is built up from individual composite hoses made from rubber, textile and steel. They have to withstand extreme operational loads (pressure, axial tension, bending, etc.) and environmental effects (drag, environmental temperature, etc.) which results a complex design and development procedure.

The development started with a preliminary analysis to determine the key parameters of the 12” inner diameter jumper line. A preliminary design was created for the hose line using the initial design input parameters (inner diameter, line length, slurry density and velocity, etc.). A thorough model of the system (vessel, vertical riser, jumper hose line) was built in a specialist software, where the jumper hose line has an „S” shape (Figure 1) achieved by attaching bouyancy modules at designated locations. The static and dynamic analysis resulted in two key parameters: weight and bending stiffness of the flexible line. The weight can be balanced by the numbers and positioning of the buoyancy modules, the main design parameter would be the bending stiffness.

Figure 1 – line layout

Achieving proper bending stiffness of a hose is mainly driven by the stiffness of the reinforcement plies, which can be fine tuned by the following parameters: main diameter (where are they located in the hose wall), base material, thickness, application angle and number of plies. Naturally, adjusting these parameters has an effect on all other Capabilities of the hose, so the design is an iterative process to reach the required behaviour. A hose body builds up form the following layers (Figure 2):

Figure 2 – hose body
  1. Abrasion resistant rubber liner with coloured wear indicator layers
  2. Main reinforcement layers: rubberized polyester cords for operational loads
  3. Secondary reinforcement: steel spiral embedded in rubber for collapse and kink resistance
  4. Main reinforcement layers: rubberized polyester cords for operational loads
  5. Special rubber compound for protection against mechanical damage as cover layers.

To be able to use the hose bodies, it certanly needs connections: ASME 14” B16.5 Class 150 Standard pipe flange were selected for the application which is applied to a steel coupling body. An individual hose length is adjusted to 22.86 m (75 ft, the length of the vertical riser elements), each one of them has reinforcement on the body close to the coupling and location collars, where the buoyancy modules can be applied. This ensures, that all hoses of a line are indentical, their position in the line can be varied at each deployment. The complete 297.18 m (975 ft) long hose line builds up as the following:
• 4 pcs of submarine hoses,
• 7 pcs of floated submarine hoses (attached buoyancy modules, 8 pcs/hose),
• 2 pcs of submarine hoses,
Prototypes have been manufactured to validate hose properties. While there are no official regulations valid for deep sea mining hoses, the GMPHOM 2009 standard and API17B recommended practice was used as guidance for testing.

Pressure (Figure 3), Vacuum, Minimum Bending Radius, Bending Stiffness, Torsional Stiffness and Axial Stiffness tests as non-destructive, Burst and Axial tension test as destructive test were performed, all with satisfactory results.