Design and Analysis of Rigid Jumpers
Contents
Design Loads
The design parameters used to analyze a rigid pipe jumper are:
- Working pressure (external hydrostatic pressure not considered);
- Temperature of the product inside the pipe, which may constitute derating the minimum yield strength of the per code;
- Insulation thickness and density required to prevent hydrate formation;
- Height of the jumper’s mating hubs off the mud line. The design of the jumper system should take into account all loads, which may be imposed as a result of the following issues:
- Fabrication, assembly, and testing loads;
- Loadout and transportation;
- Installation, including keelhauling, cross hauling, lowering to seabed, and landing. The jumper system will be assumed filled with water during deployment;
- Hydrostatic load;
- Hydrotest load;
- Fabrication and measurement tolerances;
- Thermal and pressure loads, including effect of thermal/pressure cycling;
- Wave and current forces;
- Flowline operational loads (flowline end movement due to pressure, temperature, etc.);
- ROV impact loads;
- Subsidence loads (differential settlement);
- Vibration fatigue (from unsteady flow or VIVs from currents);
- Other operation-induced loads, including drill riser/BOP movement to tree/well jumper during workover. 21.4.2.
Analysis Requirements
The jumper analysis should consider the analyses discussed next as a minimum.
Tolerance Analysis
A tolerance analysis should be performed to determine maximum allowable tolerances between mating components and subassemblies. It demonstrates that repeatable interfaces can be achieved and that connectors are fully interchangeable with mating hubs. It also determines the optimum jumper geometry for meeting functional requirements.
ROV Access Analysis
The contractor should perform an ROV accessibility analysis to demonstrate that the ROV has clear access to all ROV panels, mechanical overrides, hydraulic hot stabs, position indicators, jumper connections, etc.
Loading Analysis
The design must be confirmed through analysis of the following loading conditions:
- Transportation: Transportation criteria should be determined during the detailed design phase. The jumpers should be analyzed for transportation
to the field.
- Offshore lifting: Analyses should be performed with appropriate load factors taking into account the dynamics of the installation vessel.
- Installation: An installation analysis should be performed.
- Thermal expansion: All thermal expansion loads should be considered to establish design loads for the manifold structure and the jumper
system.
- Local stress analyses: Local stress analyses should be carried out for all joints, lifting points, and high stressed welds.
Thermal Analysis
A thermal analysis should be performed to confirm the expected time required to reach hydrate formation temperature in the jumper system. The analysis must include the jumper and the connector assembly.
Materials and Corrosion Protection
A coating system should be used for protection against corrosion. Careful attention should be given to the grounding of subassemblies to maintain continuity throughout the jumper connection system. The use of dissimilar metals in the system should be avoided.
Subsea Equipment Installation Tolerances
Tie-in connections are either vertical or horizontal based on system selection. Designed for water depths exceeding 10,000 ft (3000 m) and working pressures to 15,000 psi. Jumpers or spool pieces are installed after onshore construction and testing to mate to previously installed equipment, based on subsea metrology data. The installation tolerances of the subsea equipment may not exceed the tolerance of 2 degrees off verticality for any vertically oriented hub. Installation tolerances should be determined from the tolerance analysis of the well and flowline jumpers.
References
[1] FMC Technologies, Subsea Tie-In Systems, http://www.fmctechnologies.com/subsea.
[2] T. Oldfield, Subsea, Umbilicals, Risers and Flowlines (SURF): Performance Management of Large Contracts in an Overheated Market; Risk Management and Learning, OTC 19676, Offshore Technology Conference, Houston, Texas, 2008.
[3] G. Corbetta, D.S. Cox, Deepwater Tie-Ins of Rigid Lines: Horizontal Spools or Vertical Jumpers? 2001, SPE Production & Facilities, 2001.
[4] F.E. Roveri, A.G. Velten, V.C. Mello, L.F. Marques, The Roncador P-52 Oil Export System Hybrid Riser at an 1800m Water Depth, OTC 19336, Offshore Technology Conference, Houston, Texas, 2008.
[5] Technip, COFLEXIP Subsea and Topside Jumper Products, www.technip.com.
[6] Cameron, Cameron Vertical Connection (CVC) System, http://www.c-a-m.com.
[7] American Petroleum Institute, Specification for Subsea Wellhead and Christmas Tree Equipment, API Spec 17D (1992).
[8] American Society of Mechanical Engineers, Pipe Flanges and Flanged Fittings, ASME/ANSI B16.5 (1996).
[9] International Organization for Standardization, Petroleum and Natural Gas Industries - Design and Operation of Subsea Production Systems - Part 4: Subsea Wellhead and Tree Equipment, ISO 13628-4, (1999).
[10] B. Rose, Flowline Tie-in Systems, SUT Subsea Awareness Course, Houston, 2008.
[11] American Petroleum Institute, TFL (Through Flowline) Systems, second ed., APIRP-17C, 2002.
[12] E. Coleman, G. Isenmann, Overview of the Gemini Subsea Development, OTC 11863, Offshore Technology Conference, Houston, Texas, 2000.
