Recommended Practice for Flowline Connectors and Jumpers API RECOMMENDED PRACTICE 17R FIRST EDITION, MARCH 2015 Special Notes API publications necessarily address problems of a general nature With res[.]
Terms and Definitions
For the purposes of this document, the following definitions apply.
The tools, equipment, or materials required for the mounting, operation, and testing of the installed connector system.
This article covers essential tools and equipment for underwater operations, including inboard and outboard hub end closures, seal removal and replacement tools, and ROV interface panels with hydraulic manifolds and tubing for connector actuation It also highlights the importance of soft landing systems, jumper fabrication jigs, measurement interface caps, debris caps, hub cleaning tools, and various tools used for connection assembly and seal testing.
The maximum bending load that can be applied to the flowline jumper during installation and connector make-up is essential to account for fabrication and metrology tolerances, as well as elastic deflections caused by self-weight.
Vertical flowline jumpers need either their own weight or a pull-down force, while horizontal flowline jumpers require a pull-in force to adequately deflect the jumper This deflection is essential for properly positioning the connector onto the inboard hub for a successful connection.
The flowline geometry, external loads, contained fluid and contained fluid flow conditions, metocean conditions, and other parameters required to define the flowline jumper at any point along its length.
The actuated mechanical connector and related accessories required for its function
The components involved include the inboard hub with structure, outboard hub with connector, alignment guides, soft landing hydraulic cylinders, flowline connection structures at the flowline sleds, tie-in manifolds, line pipe, metal-to-metal seal ring, secondary seal, and fluid coupling, all essential for actuation, connector function, and seal pressure testing.
NOTE 2 The hydraulic actuators for connector make-up and/or soft landing may remain with the system, or may be recovered with a separate connector actuation tool.
An alternate seal used in place of the connector primary metal seal.
A contingency seal can be utilized if the primary seal or the sealing surfaces in the inboard or outboard hub are compromised due to physical damage, corrosion, or other factors.
Time period during which the pipeline operating temperature decreases due to a pipeline flow decrease or stoppage.
A length of pipe terminated by connector systems between two subsea structures.
Separation of the inboard and outboard hub faces at any point around the circumference caused by internal pressure, external loading, or a combination thereof.
The hub attached to the subsea structure pipe.
A connector that contains a non-removable actuation mechanism utilized to lock and unlock the connector from the inboard hub.
The act or state of the connector being fully engaged on the inboard hub and having the full preload applied.
Any connector that has more than a single bore for the transfer of fluids.
NOTE Bores may be concentric, symmetric, or non-symmetric; contained fluids may include produced and/or injected liquids or gases, hydraulic control fluids, corrosion inhibitors, and others.
A connector that utilizes an external actuation mechanism to lock and unlock the connector from the mating hub.
The hub attached to the flowline jumper pipe.
The act of landing the flowline jumper on the subsea structures in the disconnected position.
In a vertical flowline jumper, the connector is typically positioned directly above or next to the vertical inboard hub, while in a horizontal flowline jumper, it is aligned and held in a retracted position away from the horizontal inboard hub.
The flowline jumper remains stable in a parked condition, typically achieved through self-support or seabed support, except when connector actuation tools are installed for non-integral connectors.
The clamping force generated at the connection that is necessary to resist or counteract the separating forces caused by the internal pressure and/or externally applied forces and moments.
A gasket forming a metal seal in machined surfaces of the inboard and outboard hubs to retain internal flowline pressure.
A flowline jumper fabricated using steel pipe, as opposed to flexible pipe.
A metal or elastomeric seal positioned between the inboard and outboard hubs serves multiple functions, including acting as a test seal, providing a primary barrier against external ambient pressure, and serving as a secondary barrier to internal flowline pressure.
The external loading with or without RWP which the connector system is able to sustain within the accepted stress limits of the weakest component.
Stresses occurring in the subsea jumper and/or connected piping at start-up and/or shutdown due to the differential between ambient temperature and pipeline operating temperature.
A flowline jumper located between a subsea tree and another subsea structure (typically a manifold or PLET).
Acronyms and Abbreviations
EFAT extended factory acceptance testing
IOM installation, operation, and maintenance
NORM naturally occurring radioactive material
PLET pipeline or flowline end termination
SPFM single phase flow meter
General
A subsea jumper system is designed to connect subsea facilities using a rigid pipe spool or flexible pipe between hydraulic or mechanical connectors Various connector types, such as clamp, integral collet, and non-integral collet connectors, can be oriented both vertically and horizontally Notably, jumpers can be installed and removed without affecting the subsea facilities.
This section outlines the framework for selecting between different subsea jumper systems, including flexible versus rigid jumper pipes, vertical versus horizontal configurations, and integral versus non-integral connections It highlights the key variables that influence the choice of subsea jumper systems while discussing the advantages and disadvantages of each option The information aims to assist end users in their decision-making process and should be tailored to meet specific project requirements during the evaluation phase.
Subsea Jumper System Selection Considerations and Comparisons
A comprehensive technical evaluation of jumper types must be conducted alongside a project-based assessment, taking into account the total lifecycle costs of the chosen option, as well as factors such as suppliers, lead times, and procurement expenses.
The following are some advantages of flexible pipe jumpers:
— precise metrology not required for fabrication or installation provided that the subsea equipment is installed in the specified locations so that measurements can be determined during detail design;
— less sensitive to loading conditions (thermal growth, well workovers, etc.) that may cause jumper movement during operations;
— less of a concern with VIV since pipe design/configuration is self-dampening;
— corrosion resistant terminations and carcass are available for flexible pipe for sour and chemical resistant service;
— reuse of a flexible jumper may be feasible within same subsea development/range limit;
— flexible jumper can be used for very short length connections where rigid pipe may be too stiff;
— may be used for very long step outs (e.g satellite wells) where rigid pipe jumpers would not be feasible.
Figure 1—Examples of Connector Types
Three-Part Clamp With Lead Screw p
The following are some disadvantages of flexible pipe jumpers:
— fabrication and termination of flexible pipe are complex and require special tooling;
— limited qualified size, internal and external pressure ratings, and temperature ratings;
— more stringent sparing requirements due to an inability to quickly obtain new pipe;
— special considerations required for pigging;
— flexible pipe can be designed with the necessary insulating properties, but difficult to add thermal insulation after manufacture;
— special installation vessels may be needed for flexible pipe installation;
— torsional build up can occur during flexible pipe installation;
— special installation aids such as dead weights are sometimes required at first end installation of flexible pipe;
— flexible pipe with flanged or clamped end connections results in additional leak paths.
The following are some advantages of rigid pipe jumpers:
— fabrication is possible in a wide variety of working locations allowing incorporation of local content;
— pigging (wax, intelligent, and others) through steel lines is a known and fairly well understood activity (applicable to flowline jumpers only);
— HH trim CRA clad pipe is available;
— large size and thick wall is possible, and therefore wide range of pressure ratings available (internal and external pressure);
— less sensitive to sandy service;
— thermal insulation can be easily added to retain or preserve flowline content heat and extend cool down times for hydrate mitigation;
— can be welded directly to the connector thus eliminating a leak path;
— allows for the welded or flanged insertion of components into the piping such as, but not limited to, flow meters, valves, pig detectors, and sand detectors.
The following are some disadvantages of rigid pipe jumpers:
— precise metrology is required before final jumper assembly/welding and installation;
— sensitive to the deflection of wellheads and pipelines under loading (thermal, workover conditions, and others) which may cause jumper movement;
— FIV can be a concern, but may be mitigated by alternate designs/configurations, flow rates, or use of vibration suppression devices (VSDs);
— VIV can be a concern, but may be mitigated by alternate designs/configurations or by use of strakes;
— limitation on the jumper span length which may congest subsea drill centers;
— reuse of a rigid jumper is most likely not an option without modifications to the piping weldment since it is fabricated to a specific subsea metrology.
The following are some advantages of horizontal jumpers.
Horizontal jumpers are essential for projects that need self-draining and low-profile solutions to safeguard against fishing activities, trawling boards, and icebergs in shallow water depths.
— Lifting height at quayside and on installation vessel may be shorter.
— Tie-in porches may support horizontal jumpers in a disconnected state while retrieving the host structure (such as a manifold or tree), depending on subsea foundation.
— Metrology may be taken from the tie-in porch structure prior to the installation of the host structure in some cases.
— Horizontal connections may also be installed on subsea support structures prior to the installation of the host structure (manifold, trees)
— Lower jumper height minimizes interference with intervention and production equipment.
— Horizontal jumpers are less susceptible to VIV due to lower profile and seabed support.
— Horizontal jumpers are typically designed to lie on the seabed, which reduces loads applied to the inboard hubs. The following are some disadvantages of horizontal jumpers.
— Stroking tools and tie-in porch are required to apply and react forces necessary for connector pull-in and push- back from inboard hub.
— A vertical run must be incorporated into the horizontal jumper configuration in order to incorporate a multiphase flowmeter in the preferred vertical orientation.
Horizontal jumpers are often constructed in various planes, which can result in residual stress (tension) remaining in a rigid horizontal jumper after the connections are made, depending on the jumper's design.
— A rigid horizontal jumper requires more deck space than a rigid vertical jumper during load out and transportation.
— Metrology for horizontal jumpers should include heading, and the survey points on the subsea structure varies depending on the connection system.
— Retrieval of a horizontal jumper may be difficult due to the multi-planar design of most horizontal jumpers.
— Jumper insulation may require installation of doghouses over connectors.
— More space is required to fabricate horizontal jumpers due to large footprint required for out of plane designs.
— Installation rigging for horizontal jumpers is more complicated in most cases and may be very large.
The following are some advantages of vertical jumpers:
— do not require complex landing porches;
— minimal pipe deflection/pull-in required when making up the connection;
— allow integration of a multiphase flowmeter in the preferred vertical orientation on the jumper;
— typically fabricated in a single plane which aid in installation and retrieval;
— installation of post-installed insulation doghouses is simplified;
— metrology is simplified and can be taken directly from the structure hub.
The following are some disadvantages of vertical jumpers:
— undesirable in shallower water depths where fishing nets/trawling boards are employed and/or icebergs may be encountered;
— typically cannot be parked in order to retrieve the host structure;
— are more susceptible to VIV and fatigue due to exposed profile.
4.2.3 Integral vs Non-integral Connectors
The following are some advantages of integral connectors for jumpers:
— decreased installation time since no separate trips are required to retrieve connector actuation tools because all actuation and soft landing mechanisms are integral to the connector;
— advantageous for developments which require smaller number of connections;
— not subject to obsolescence of changes in design;
— not dependent on availability of connector actuation tools, especially when compared to non-integral connector designs that have been modified or replaced by newer models;
— wet insulation can be pre-installed versus post-installation dog house.
The following are some disadvantages of integral connectors for jumpers:
— higher hardware cost per connection, but lower tooling rental cost;
— all hydraulic components remain subsea, which introduces additional potential failure modes.
The following are some advantages of non-integral connectors for jumpers:
— connector actuating hydraulics can be integrated into the stroking tool, which reduces hardware cost per connector by removing the hydraulics from each connector;
— advantageous for fields which require larger number of connections (also depends on the number of tools required during the installation campaign);
— increased reliability of the actuation system, because all hydraulic components are recovered with the connector actuation tools and can be maintained/repaired prior to use;
— cost increases can be minimized by utilizing connector designs with nonproprietary or simplified ROV tools (e.g clamp connectors) or by renting the tools.
The following are some disadvantages of non-integral connectors for jumpers:
— longer installation time, because additional trips may be required for recovery of connector actuation tools;
— require upkeep, maintenance, and storage of the proprietary connector actuations tools over the course of the field life.
Jumper Configurations
Jumper configurations include, but are not limited to, those shown in Figure 2
The jumper configuration should be optimized for transportation to the field and to minimize ROV obstacles
A self-sustaining jumper configuration eliminates the need for soil support, integrates buoyancy modules or bend restrictors, and strategically places additional hardware to reduce the impact of bending loads.
When seabed support is required, soil data should be obtained and used to analyze the jumper for support as well as the induction of loading.
The project necessitates supplemental hardware, including MPFM, SPFM, and valve modules, which often require interfacing with hydraulic or electrical flying leads, thereby imposing additional loads on the jumper connection.
Field commissioning plans should specify whether the jumper configuration needs to facilitate pigging.
Drill Center Layout Guidance
The positioning of vertical jumpers is crucial for establishing the placement of trees relative to the manifold Typically, rigid vertical jumpers with nominal pipe diameters of 6 inches and 8 inches have a standard range of 50 to 90 feet.
When designing subsea jumpers ranging from 15 m to 27 m, it's crucial to balance length and flexibility A jumper that is too short may be overly rigid, necessitating an increase in height to accommodate installation deflections Conversely, a longer jumper could require a larger installation vessel, leading to heightened stresses and complicating handling and installation Typically, rigid subsea jumpers with a nominal pipe diameter smaller than 4 inches are avoided due to their excessive flexibility and short span length.
Larger diameter rigid jumpers, particularly those utilized in flowline and pipeline applications, exhibit a distinct length variation Typically, rigid vertical jumpers with nominal pipe diameters of 10 inches and 12 inches range from 80 feet to 130 feet (24 meters to 40 meters).
When planning the drill center layout, it is essential to assess the jumper configuration and routings alongside all subsea system components to reduce the crossing of flowlines, umbilicals, flying leads, and other jumpers Additionally, jumper selection must take into account the drilling sequence and the potential effects of external drill cuttings accumulation, especially if jumpers and flying leads are pre-installed and later repositioned.
Traditional Flexible (Horizontal) Traditional Flexible (Vertical)
Multiple M W Shape Double L Three-dimensional (3D)
When jumpers are crossed, it is essential to conduct jumper analysis, ROV accessibility analysis, metrology feasibility analysis, and any other necessary evaluations to demonstrate that the crossed jumper represents the most feasible solution.
Requirements During Installation (that Influence Jumper Selection)
When selecting a jumper configuration, it's essential to consider specific installation requirements that may influence the choice The advantages and disadvantages of horizontal versus vertical jumpers, as well as integral and non-integral connectors, are outlined in section 4.2 Regardless of the materials used or their orientation, jumper configurations must be designed to withstand the installed sea state, as improper design can lead to immediate failure due to installation loads The jumper should be able to descend under its own weight without creating excessive slack in the supporting rigging equipment Furthermore, each jumper connector must be equipped with the appropriate hardware to ensure proper alignment and prevent damage during landing.
Unbalanced loads from varying connector sizes can complicate the configuration of spreader bars and lift lines for rigid jumpers It is essential to assess the installation vessel's capabilities, including deck space, crane hook height, and lift capacity, during the evaluation process.
The minimum bend radius for flexible jumpers defines the tightest curvature they can safely endure Installing bend restrictors on the outer coating of flexible jumpers can prolong installation time, particularly at end connections where production shut-in may be necessary If the minimum bend radius is surpassed, it is crucial for the flexible pipe manufacturer to assess the potential long-term performance impacts.
ROV/ROT Aspects
When designing connectors, manufacturers should adhere to API 17H standards to ensure compatibility with standard ROV tooling, making all interfaces ROV-friendly and accessible It is crucial that these interfaces can endure incidental ROV loadings Additionally, any extra components added to the pipe spool and connectors, like isolation valves or subsea flow meters, require an ROV accessibility study to verify that there are no clashes with nearby subsea hardware.
Multibore Connection Systems
Multibore jumpers combine production, chemical, and hydraulic lines into a single bundle, significantly reducing installation time By utilizing a multibore connector, these lines can be installed and connected simultaneously, providing improved protection for each individual line.
Multiple bores in a single outboard hub add complexity to the connection system The following are advantages and disadvantages of multibore connection systems.
Multibore connection systems can be classified as either concentric or nonconcentric Concentric systems allow for easy installation since they do not necessitate the rotational alignment of the outboard and inboard hubs In contrast, nonconcentric systems require precise rotational alignment between these hubs for proper functionality.
— Multibore connection systems may include integral bores with metal seals for production, water injection, chemical injection, and hydraulic fluid, as well as accommodate hydraulic, electrical, and fiber optic connectors.
— Multibore connection systems may require specialized manufacturing, assembly, and welding techniques.
— The individual metal seals used in a multibore application should be qualified to accommodate the axial and radial tolerances required for machining the outboard and inboard hub sealing surfaces.
— Subsea seal replacement in multibore connection systems may require complex seal replacement tools.
— Intervention requires disconnection of all bores.
Any internal components that are not integral to the multibore connection system outboard hub, inboard hub, and primary and secondary seals are outside the scope of this RP.
General
This section outlines the requirements for devices that establish and maintain connections between pressure-containing structures, including connectors, caps, and closures.
Functional Requirements
The connection system should have the following functional requirements.
The connector must be designed to ensure that all components remain secure and stable during the transition from fully unlocked to fully locked positions, especially for designs that permit extra locking stroke when not mounted on an inboard hub.
— At the conclusion of FAT, the connector should be interchangeable on all hubs designed for the connector without requiring adjustment.
— The connection system should accommodate the capability to allow for connector cleaning tools and gasket replacement tools.
— The connection system should include visual indication to confirm the outboard hub is correctly landed on the inboard hub before locking
— The connection system should include visual indication of lock and unlock.
— The connector should provide for gasket retention and protection during installation.
The connector must be properly aligned with the hub prior to engaging the gasket It is essential to allow the gasket to self-align within the grooves during this process to ensure a proper fit with the hub profile.
The connector and inboard hub must effectively manage radial, angular, and axial misalignment caused by inaccuracies and deflections during flowline and jumper fabrication, while adhering to the manufacturer's rated specifications and metrology tolerances.
The connector actuation tool must possess adequate capacity to address jumper misalignments and pull-in loads, ensuring it meets the manufacturer's specified ratings for bending moment, torsion capacity, shear force, and axial force during the locking process.
The connection must enable a post-installation pressure test to confirm that the seal is intact without pressurizing the connector's bore This is usually achieved through a low volume annular test conducted externally to the primary seal.
When employing a wet-mated seal with both primary and secondary seals for bore fluid applications, it is essential to test both components to verify seal integrity Additionally, if the test circuit is exposed to bore fluid, it must be securely closed off with a mechanism that is compatible with the specific bore fluid being used.
For connectors with a permanent primary unlocking mechanism, a secondary unlocking method must be provided to ensure functionality if the primary mechanism fails This secondary method should be operable by an ROV and capable of applying twice the force necessary to unlock a new connector, based on results from connector design verification and validation testing.
Connectors lacking integral unlock features must include a secondary unlocking method that can be operated by an ROV tool It is essential to plan for contingencies in case the primary unlock interface of the connector becomes inoperable.
— The gasket should be replaceable subsea using ROV deployed tooling.
In displacement-controlled applications, the minimum preload must be determined by considering the worst-case machining tolerances that impact the preload Conversely, designs that achieve preload through force, such as taper lock or threaded systems, can employ mathematical models to estimate preload, supported by data obtained from validation testing.
To ensure the protection of gaskets during installation, connections must incorporate a soft land system, dampening system, or similar methods It is essential that this approach is validated through rigorous testing, including validation testing or other forms of physical assessment.
— The horizontal connector and/or connector actuation tool (as applicable) should be designed to withstand the manufacturer’s rated shear force in all directions during final alignment imparted during guidance.
Design Requirements
The connection system should have the following design requirements.
The connector must be engineered to remain securely locked without relying on external forces or pressures This can be achieved by incorporating a secondary locking mechanism, which aims to prevent the unintended unlocking of the connector's locking components caused by external loads.
— The connector primary locking mechanism and secondary locking mechanism (if applicable) should be designed so as not to be affected by vibration.
— The manufacturer should state the design life of the connector considering all applicable limiting factors including, but not limited to, service, temperature, fatigue, cathodic protection, and elastomeric seals.
The seawater depth capability of the connection should be determined by the manufacturer, focusing on the external capacity of the primary seal or the weakest mechanical component that could lead to subsea leakage The more limiting factor will dictate the overall depth capability.
The manufacturer must specify the number of lock/unlock cycles a connector can endure before refurbishment, which includes recoating or relubricating Additionally, this rating should account for any reduction in load or capacity that may occur with an increased number of cycles.
— A connector is considered field serviceable or maintainable only if the connector components are removable without cutting the jumper pipe or disconnecting flowline flanges
— Connector working capacity should be defined as the lesser of the following.
The preload of a connection system can drop to zero, regardless of whether RWP is applied, but this loss does not always lead to leakage To assess preload limits for axially symmetrical connections that maintain uniform preload at the hub faces, hub face separation is a useful method In contrast, for axially non-symmetric connectors with varying contact pressures at the hub faces, the locking mechanism pre-tension should be utilized to establish the preload limit.
— The structural capacity of the connector components exceed stress allowable limits as defined in 5.4.4 prior to loss of preload occurring
Manufacturers must collaborate with end users to establish design verification and validation methods when connector capacities exceed the specified working limits for particular product applications.
Hub separation at the gasket location is permissible as long as the measured hub separation distance is quantified and does not exceed the qualification limits of the gasket It is essential that no leakage occurs during the validation testing process.
— Torsion slippage should be defined as permanent rotational movement of the connector in relation to the inboard hub The connector torsion capacity should be documented by the manufacturer.
A torsionally rigid connector's capacity is defined as the maximum load at which slippage occurs between the connector and hub, capped at 90% with RWP applied While slippage may not immediately lead to fluid leakage, it signifies a failure in the connection Notably, the torsion capacity generally increases as internal pressure decreases.
To ensure optimal performance, it is essential to validate the sealing capability of connectors and gaskets when slippage is permitted, confirming their ability to endure the specified angular displacement and cycles Additionally, the end user must assess and approve the validation criteria in relation to the product's intended application.
The connector's structural capacity must exceed the design capacity of the associated pipe If this is not the case, the jumper system should be rated according to the connector's capacity or any other limiting component.
— Considerations should be made for long-term environmental exposure of hydraulic connector sealing and interface surfaces that may impact unlocking and disconnection of the connector from the inboard hub.
Sealing components in hydraulic circuits must be designed to withstand both minimum and maximum temperatures they will encounter, even if these temperatures are higher than ambient but lower than the bore fluid's maximum Additionally, the insulation of the connector can influence the hydraulic system's temperature range.
— The connector system, including all components in the locking mechanism, should be designed for the maximum locking force in combination with the lowest coefficient of friction
The design of the connector's unlocking force must be at least double the maximum unlocking force established through verification and validation testing It is essential that all components within the unlocking mechanism are engineered to withstand the specified design unlocking force for both mechanical and integral hydraulic connectors.
— The manufacturer should state the RWP of the integral hydraulic chambers and ports, and test them to 1.5 times RWP
— The connector should be designed to accept a primary metal sealing gasket Considerations should be made for a contingency gasket, which may be metal and/or resilient sealing type.
To ensure the integrity of the seal pocket, it is essential to design the gasket and mating seal pocket in a way that reduces the risk of damage during standard connector operations, including landing, locking, unlocking, hub cleaning, and seal replacement.
The connector system must be engineered to meet the temperature range requirements outlined in API 6A and API 17D, or other defined minimum and maximum operating temperatures Manufacturers may designate an alternative temperature range for components not in direct contact with production fluid, provided this is validated through thermal analysis or testing as per API 17D standards.
— All lift points should be designed and proof load tested per API 17D Annex K or comparable codes Compliance with applicable regulatory requirements should also be ensured.
— Connector pull-in capacity to be defined by the manufacturer.
Design Verification Requirements
The connector system design verification should meet the following requirements This may include classical calculations and/or FEA For more detailed requirements, refer to the appropriate codes.
Design verification should be performed using one of the following methodologies: a) linear elastic, b) elastic/perfectly-plastic with small deflection theory, c) elastic/plastic with strain hardening and large deflection theory.
The design verification may be performed using classical calculations for method a) above and/or by using FEA for methods a), b), or c) above.
The design verification methodology may be in accordance with other recognized standards including any of the following:
The following requirements should be included when performing the design verification.
— Design verification should be performed for all load bearing cross sections of the connector system including the outboard hub and inboard hub
— As applicable, the maximum preload, internal pressure (RWP and hydrostatic test pressure), tension shear and bending moment should be included for design verification
— Minimum preload should be analyzed to verify bending capacity.
— Temperature derating of material properties should be included where applicable.
— Nominal material dimensions may normally be assumed, but the effect of tolerances and corrosion/erosion should be included when their effect is significant.
— The effect of varying friction coefficients should be analyzed when applicable.
— Buckling should be analyzed if relevant.
— Displacement at threads and collets should be analyzed to ensure loss of engagement does not limit design capacity.
— The impact of thermal and pressure cycling on the connector sealing capability and components should be analyzed.
5.4.3 Finite Element Analysis General Requirements
When utilizing Finite Element Analysis (FEA) for design verification, it is essential to include separation load(s) and relaxation rates at the connector/hub interface, particularly near the gasket For non-symmetric connection systems, loads should be applied to the weakest section to accurately determine separation loads, which will serve as acceptance criteria for assessing connector bending capacity during verification testing Additionally, connector designs featuring a lock ring must be modeled in 3D, especially when tangential stresses are critical Lastly, connectors experiencing asymmetric loading, such as bending moments, should be analyzed using appropriate modeling strategies.
1) axisymmetric geometry with axisymmetric loads (i.e equivalent tension);
2) initially axisymmetric geometry that models asymmetric loads/response;
3) minimum half 3D geometric symmetry (half collet segment model, half model with symmetric loading);
When conducting full 3D finite element analysis (FEA) for non-symmetric geometries under non-symmetric loading, it is essential to model at least 180 degrees of the circumference If a half collet segment is utilized, the manufacturer must demonstrate that the bending moment direction is conservative regarding both structural and pressure integrity The equivalent axial tension method may not fully account for the effects of bending moment loads, particularly compression effects that could compromise connector integrity Additionally, the mesh density must be suitable for the geometry, with a finer mesh recommended in critical areas to meet local strain criteria or for fatigue assessments For elastic/plastic analysis involving strain hardening, materials should be represented using true stress-strain curves from actual test specimens or by employing the material model outlined in ASME Section VIII, Division 2, Annex 3D, which is based on specified minimum yield strength, minimum tensile strength, and Young’s modulus.
The manufacturer should use one of the following three analysis methods (linear elastic, elastic/plastic, or elastic/ perfectly plastic) to determine connector component and system strength acceptability.
Elastic analysis assumes a linear stress/strain relationship without yielding or plastic behavior, necessitating stress limits as per API 6X, Section 4 The design stress intensity must be two-thirds of the minimum specified strength, while the maximum allowable general primary membrane stress intensity during hydrostatic testing is capped at 90% of the minimum specified yield strength Additionally, the combined local membrane and primary bending stress intensity should not exceed the specified minimum yield strength The von Mises equivalent stress method can be utilized to combine stress components in place of stress intensity where specified in the standard.
5.4.4.3 Elastic/Plastic and Elastic/Perfectly-Plastic Analysis
When utilizing the elastic/plastic or elastic/perfectly-plastic analysis method, it is essential to adhere to specific acceptance criteria First, normal design loads must be restricted by applying suitable load or utilization factors to the structural limit load Additionally, hydrostatic test pressure loads should also be constrained using the appropriate load or utilization factors relative to the structural limit load Finally, the structural limit loads must comply with established guidelines.
1) elastic-plastic stress analysis method according to ASME Section VIII, Division 2, Part 5;
The elastic-plastic stress analysis method outlined in ASME Section VIII, Division 3 is essential for high-pressure, high-temperature (HPHT) applications When utilizing this standard to assess structural capacity, it is crucial to conduct the analysis in conjunction with Article KD-4.
Design Validation
For design validation requirements, consult API 17D and API 6A This section outlines the minimum recommended testing guidelines for connector system qualification, where the term "connector" encompasses the mating hub Additionally, it applies to end closures intended to serve as primary containment barriers for production fluid.
Validation testing should include the following actions.
— Validation testing should be performed on a full scale connector All critical geometries of the test components should be representative of the production connector
The test connector and other pressure-containing components intended for design validation must undergo hydrostatic testing at 1.5 times the rated working pressure (RWP) in compliance with the relevant API 6A standards prior to validation testing.
— Change to critical sealing, load bearing or locking geometries requires requalification.
The stiffness of test equipment must replicate that of production equipment When using blinded bodies, it is essential to incorporate adequate bores to ensure that the load-induced stresses in the connector are similar to those experienced in production bodies.
Maintenance on prototype connectors must align with that of production connectors, ensuring that tasks such as recoating or relubricating are performed according to the same schedule, if applicable.
Testing must confirm that the connector design generates sufficient locking force to meet the necessary preload in practical applications This can be validated by measuring hub face separation or by comparing strain gauge data with finite element analysis (FEA) results.
— Pressure cycling and pressure hold acceptance criteria should conform to API 17D and API 6A Annex F requirements for PR2 other end connectors.
Hydraulic connectors, such as integral hydraulic connectors, must undergo pressure testing in accordance with API 6A and API 17D standards This testing applies to both low and high-pressure hydraulic actuators, ensuring there is no visible leakage and that all acceptance criteria outlined in API 17D are met.
During the validation testing of connector design, it is crucial that the primary lock of the connector remains unenergized This can be achieved by avoiding any externally applied force from a connector actuation tool or by not maintaining pressure in a locking circuit for integral connectors, ensuring that the connector stays securely locked.
— If a secondary lock is included in the connector design, it should undergo a separate test from the primary lock without the use of external force or pressure being maintained.
Connector seals must undergo testing for both the rated internal working pressure and the maximum external pressure Additionally, temperature testing within the minimum and maximum range at the rated internal working pressure is required, adhering to API 6A Annex F standards for PR2 other end connectors Acceptance criteria for all seal testing should align with the API 6A Annex F guidelines for external closures, and this testing protocol also extends to connector contingency seals Comprehensive seal testing should encompass these essential actions.
Seal integrity testing can be conducted either in the connector itself or using a test fixture that accurately represents the production connector It is essential that the test fixture mirrors the critical geometries and is made from the same materials and yields as the production connector Additionally, the test fixture must apply the same preload conditions experienced by the production connector to ensure reliable testing results.
— The seal should undergo a 1.5 times RWP test prior to performing API 6A, Annex F testing.
— Testing should include provisions to apply pressure to the seal externally to simulate hydrostatic pressure at water depth
— Testing should include an annulus test such that the primary seal can be tested to the external pressure rating of the gasket.
— If the connector seal contains a secondary seal, both seals should be tested individually for external pressure resistance.
— The connector seal should be rated for pressure differential external to internal, to assess the suitability of the seal for a specific water depth rating at minimum internal pressure.
Gaskets featuring secondary or multiple seals for a shared barrier must undergo individual testing for each seal according to Annex F thermal cycling to qualify as authentic secondary seals.
When designing connectors with additional sealing components, such as integral hydraulics or gallery seals, it is essential to conduct thermal testing on these seals Manufacturers must perform pressure tests at both minimum and maximum operational temperatures, adhering to API 17D standards Furthermore, these seals should endure the extreme temperatures experienced during production to ensure their suitability for intended applications.
Load and cycle testing is essential to validate the design and document the performance characteristics of connectors This testing aims to establish the preload limit under different loading conditions, taking into account the connector's locking force Additionally, manufacturers should specify the rated capacity for combined loading and conduct tests to confirm this rating.
Load and cycle testing can be conducted at ambient temperatures; however, for connectors used in high-temperature applications, it is essential to derate materials for yield strength To validate the design, special measures such as Finite Element Analysis or physical testing as per the manufacturer's guidelines should be implemented Caution is crucial when performing thermal testing on connections under pressure and load due to the significant potential energy involved.
Unless previously performed on the connector, a hydrotest to 1.5 times the RWP should be performed prior to any load and cycle testing.
To verify the connector's capacity, it must undergo bending moment loads in a test fixture that simulates actual conditions, including internal pressure, tension, torsion, shear, and bending loads The design external load or load combinations should be applied to the connector at least three times during the testing program to establish its bending capacity curve Additionally, the testing should encompass both bending and torsion assessments.
Strain gauges are essential for monitoring preload and stress in critical connector components during testing It is important to validate this data with classical methods or Finite Element Analysis (FEA) results when applicable.
Factory Acceptance Testing of Connectors
Factory acceptance testing involves procedures such as lock force or pressure setting, function testing, and hydrostatic pressure testing, which are conducted either after or alongside connector assembly It is essential that factory acceptance testing encompasses these critical actions to ensure product reliability and performance.
— Individual connector kits/assemblies may be closed upon and pressure tested on a test hub which has the same interfacing geometry as a production hub.
— Where applicable, actuation of a connector should be performed by the connector actuation tool or general equivalent, so that interfaces between the connector and the connector actuation tool are verified.
— All factory acceptance testing should be completed using a production seal or a metal to metal seal which is representative of a production seal
— Connector lock, unlock, secondary unlock, and other connector specific functions should be tested per API 17D.
Integral hydraulic connectors must undergo hydrostatic shell testing for each hydraulic chamber and its corresponding circuit This testing should reach a minimum of 1.5 times the rated working pressure, sustained for at least 3 minutes, ensuring no visible leakage Compliance with the acceptance criteria outlined in API 17D is essential.
When setting the connector preload, it is essential to consider the manufacturing tolerances of the hub Adjust the connector locking pressure according to the manufacturer's hub divergence factors to ensure that the connector achieves the specified rated preload when secured to a hub that meets nominal manufacturing tolerances.
— During manufacturing, FAT, EFAT, and SIT, each connector should follow its established refurbishment guideline (as required by number of lock cycles).
— Operating times for connector functions should be specified in the FAT procedure, as required to emulate field operations, and operate within any critical parameters established during design validation.
— The minimum and maximum locking force, pressure, or torque should be specified in the FAT procedure.
— The connector and hub should be hydrostatically tested to 1.5 times RWP unless limited by attached components that are governed by a different code, e.g a pipeline code allowing for a hydrotest of 1.25 x RWP.
For multibore connectors, it is essential to individually pressure test each bore to 1.5 times the rated working pressure (RWP), unless restricted by connected components Additionally, all bores must undergo simultaneous pressure testing at the RWP.
Before conducting any bore tests, it is essential to perform an annulus test on the metal seal to ensure its integrity In cases involving multiple bores, this test can be executed on each seal individually or on all seals at once.
After the FAT, it is essential to conduct a visual inspection of all accessible connector surfaces for any signs of damage Minor burnishing and rubbing or scuffing marks on the connector and hub contact surfaces, which are non-sealing areas, are considered normal and do not warrant rejection.
— Insulated connectors may be factory acceptance tested either before or after application of insulation The factory acceptance testing program for insulated connectors should confirm the following requirements:
— Insulation does not mask defects or leaks.
— Application of insulation does not damage hydraulic lines or other external features.
— Insulation does not prevent normal operational sequences for locking/unlocking in order to achieve full preload.
— Insulation does not interfere with connector actuation tool or other interfacing equipment (e.g hub cleaning or gasket change-out tooling).
Connector Documentation
The following section provides a list of connector documentation, which should be generated and included in the equipment design file This documentation should be available for review by the customer.
This document outlines the assembly procedure for production connectors, incorporating essential standard bulletins for the facility, including safety guidelines and part checklists.
Product data sheets are documents containing technical information comprised of the following:
— connector system cross section with labeled components;
— connector system bending capacity chart(s);
— connector system torsion capacity chart(s);
— connector (or connector actuation tool) pull-in capacity;
— maximum misalignment angle for outboard hub landing (or pull-in, if applicable) onto inboard hub; and
— maximum misalignment angle for outboard hub locking onto inboard hub, if different from maximum misalignment angle for outboard hub landing.
The technical specification sheet must include essential information presented in both imperial and metric units For non-integral hydraulic connectors, certain details should correspond to the external connector actuation tool system utilized and should be clearly labeled.
— secondary piston unlock area (if applicable);
— piston/stroke lengths for actuation and softland (or pull-in, if applicable);
— fluid volume (secondary unlock chamber, if applicable);
— fluid volume for softland (or pull-in, if applicable);
— minimum required locking pressure (minimum required torque, if applicable);
— maximum allowable locking pressure (maximum allowable torque, if applicable);
— maximum allowable softland pressure (or pull-in pressure, if applicable);
— maximum bending and torsion capacities at working pressure; and
— maximum bending and torsion capacities at zero internal pressure.
Bending capacity charts illustrate the relationship between internal pressure and bending capacity, with internal pressure plotted on the x-axis and bending moment on the y-axis These charts may feature multiple capacity lines, each corresponding to different gasket or bore sizes and tension levels In cases where only one gasket size is used, it is essential to include a note specifying the gasket size and type An example of such a chart, depicting bending capacities for a single connector size under four hypothetical tension loads, can be found in Figure 3, although axis ranges, units, and connector gasket size have been simplified for clarity.
Torsion capacity charts illustrate the relationship between torsion capacity and internal pressure, with internal pressure plotted on the x-axis and torsion on the y-axis These charts may feature multiple capacity lines, each corresponding to different gasket or bore sizes and varying tensions In cases where only one gasket size is used for the connector, it is essential to include a note specifying the gasket size and type An example of such a chart, depicting the maximum torsion before rotational slippage for three hypothetical load cases with a single connector size, is shown in Figure 4, although axis ranges, units, and connector gasket size are omitted for clarity.
The design validation test report must encompass all pertinent test results from the design validation testing, highlighting essential information regarding the connector design This key information, derived from testing, includes various critical aspects of the connector.
— connector locking pressure sensitivity to hub profile tolerances (if applicable);
— lock-to-unlock pressure ratio and lock pressure to mechanical unlock force (if applicable);
— connector mechanical advantage (design validation testing);
— hub separation load relaxation rates before and after hub separation (if applicable) at various locking pressure (preload) settings and external load conditions;
— torsion capacity of the connector (if applicable) or torsional value at which hub slippage occurred (if applicable).
The FEA report should present all relevant finite element analyses performed on the connector design The FEA report should include the following key sections.
— Introduction—provides general information about the connector and the analyses, background, and scope.
— Conclusions—presents a summary of the main conclusions derived from the analyses, and provides data that should be used for comparisons between FEA predictions and test results.
— Model description—provides details about the models used in the FE analyses, such as, but not limited to, model dimension (2D vs 3D), degrees of freedom, contact elements, and material properties.
Figure 3—Bending Capacity Chart Example
Figure 4—Torsion Capacity Chart Example
Tension value 3 Tension value 2 Tension value 1 Tension = 0
The section on applied loads and boundary conditions outlines the various load cases analyzed and details the boundary conditions set for the model, including aspects such as fixity and the specific locations where loads are applied.
— Discussion of results—covers key details of the analyses and may include, but is not limited, to the following:
— plots of preload actuation force/pressure during preloading;
— plots of hub face preload vs actuation;
— plots of loads between different components vs preload and vs applied load;
— plots of seal contact pressure or line load vs preload and vs applied load;
— plots of deflection vs applied load (i.e deflection due to bending);
— plots of plastic strain vs applied load;
— identification of limiting component(s) and failure mode(s).
— References—codes, drawings, material specifications.
— Appendix—provides material information and all FEA tables and plots gathered through the analyses.
The following comparisons should be made between FEA predictions and actual test results:
— characteristics of the lock stroke and the mechanical advantage;
— temperature under external load and/or internal pressure;
— radial thread deflection (if applicable);
— radial actuator ring deflection (if applicable); and
— critical component stress or strain comparison.
The Product Design Document (PDD) outlines all design calculations for a specific connector, including details on the connector assembly, outboard hub, and inboard hub, while excluding gasket design analysis Key sections of the PDD must be included to ensure comprehensive coverage of the design process.
— Scope—briefly defines the scope of the analyses.
— Assumptions—states all assumptions made in the design calculations.
— Function—briefly describes how the connector operates.
— Parameters—defines bore size and external load limitations.
— Reference documents—list of all industry codes and standards used to define stress limitations.
— Reference drawings—list of drawings, layouts, and sketches pertaining to the connector and identification of critical geometry.
— Material properties—list of material properties.
— Design analyses—list of all calculations performed on the connector design.
Pressure Caps
This section includes information on pressure caps/end closures for both the inboard hub and connector
Inboard hub pressure caps and end closures are essential components for all inboard hubs, enabling effective pressure testing of subsea structure piping during fabrication and after installation They act as a secondary pressure barrier, allowing for the installation of subsea structures prior to the manufacturing of jumper connectors or fabrication of jumpers, while also protecting the sealing surfaces of the inboard hub These caps and closures can be categorized into different types based on their specific functions.
Pressure caps designed for surface use generally feature a blind hub and a split clamp or similar mechanism to secure the blind hub to the inboard hub, effectively supporting the pressure end load These caps can be made from either metal or elastomeric sealing materials.
— Surface installed, ROV removable These pressure caps are typically disengaged from the inboard hub by a simple ROV operable mechanism.
— ROV installable and removable These pressure caps are fully operable by ROV.
Inboard hub pressure caps and end closures can be engineered for either temporary or permanent applications The choice of materials, such as elastomeric or metal seals, along with cathodic protection requirements, is usually influenced by the anticipated subsea lifespan and the design of subsea facilities Additional design features for these pressure caps and end closures may vary widely.
— allow flooding of a flowline after installation (flooding cap);
— have an annulus test port to allow confirmation of sealing integrity;
— have supply and bleed ports to allow venting of trapped pressure before removal and injection of chemicals (very important if hydrate formation below cap may occur);
5.8.3 Connector Body/Outboard Hub Pressure Caps/End Closures
High-pressure caps for connector bodies or outboard hubs can be utilized to enable hydrostatic testing of jumpers post-fabrication These caps may feature the same interfacing geometry as the inboard hub, secured by the connector's actuation, or they may employ a different locking and sealing mechanism Additionally, they are designed with porting to facilitate flooding and pressure testing of the jumper.
Connector body or outboard hub low-pressure end closures can be provided to enable surface filling of a jumper before it is lowered to the seabed Once at the seabed, these closures can be disengaged and removed, allowing the jumper to connect to the inboard hubs of subsea structures It is essential that these closures are operable by ROV and include a pressure equalization feature to avoid hydraulic lock.
Debris Caps
Debris caps provide short-term protection for inboard hubs when pressure caps or end closures are absent, safeguarding sealing surfaces from accidental damage Typically non-pressure containing and non-fluid retaining, they are engineered to prevent hydraulic lock Additionally, debris caps can be utilized in connectors to shield seals and mating faces during storage and transportation Designed for easy installation and removal by an ROV, these caps must be securely fastened during offshore operations and subsea installations to avoid unintended release.
Tooling
This section covers essential subsea tooling, such as connector actuation tools, measurement tool interfaces, seal replacement tools, hub cleaning tools, and connector override tools All subsea tools must be designed with ROV interfaces that comply with API 17H standards Furthermore, these tools should be qualified to ensure optimal performance under the specific loading conditions and misalignments encountered in the connection system.
Connector actuation tools are essential for the installation and operation of non-integral connectors, typically operated by an ROV These tools facilitate the landing and alignment of connectors with the inboard hub, utilizing soft landing cylinders for vertical connectors or stroking cylinders for horizontal connectors to ensure a controlled connection They also include actuation cylinders that provide the necessary locking and unlocking force to secure the connector to the inboard hub, and may assist in testing the connector's metal seal annulus Additionally, these tools should feature a locking mechanism to securely attach to the connector during installation ROV-operated torque tools are commonly employed to actuate clamp-style connectors.
Measurement tool interfaces serve as attachment points on an inboard hub or its pressure cap for the installation of measurement tools or receptacles The precise location of these interfaces is defined in relation to the inboard hub pipe axis and mating face, enabling accurate metrology to position fabrication hubs relative to each other during jumper fabrication.
Seal replacement tools are essential for removing and replacing metal seals on outboard hubs These tools can be designed for surface use or for subsea operations with a remotely operated vehicle (ROV) When used subsea, it is crucial that seal replacement tools are user-friendly and easily operable by an ROV.
Hub cleaning tools are essential for eliminating debris and calcium carbonate from sealing and mating surfaces These tools can be operated manually or hydraulically by remotely operated vehicles (ROVs) It is crucial to test hub cleaning tools to establish the operational parameters needed to avoid excessive removal of hub material.
Connector override tools are essential for unlocking connectors from inboard hubs when standard unlocking methods are ineffective or unavailable These tools can be deployed from the surface and operated hydraulically by a remotely operated vehicle (ROV) They are designed to provide the necessary force to unlock connectors, ensuring reliability even under the highest required unsetting conditions.
An ROV can utilize a grinding or cutting tool to cut through a clamp style connector's actuating screw, effectively separating the clamp segments and releasing the connector from the inboard hub.
General
The jumper, alongside the Connector System, may incorporate pipes, forgings, and specialized instrumentation Additionally, it functions as a support structure for various components, including anodes, VIV suppression systems, VSDs, buoyancy aids, and attachment or parking appurtenances for electric or hydraulic lines.
Pipe
Jumper pipe may be rigid pipe or flexible pipe
The design of rigid pipes must adhere to pressure pipe design codes established by the principal, owner, and regulatory bodies, such as ASME B31.8, API 1111, and DNV-OS-F101 In contrast, flexible pipe design should comply with standards and recommended practices, including API 17B, API 17J, and API 17K In subsea projects involving a combination of jumpers, such as flowline to manifold and manifold to tree jumpers, different pressure design codes may apply to each application These codes also provide lists of acceptable materials for pipes and fittings, although this RP does not aim to enumerate all acceptable materials.