AOG-2015 POLARLED 36 OPTIMA CLAMP CONNECTOR CASE STUDY

Transcription

1 AOG-2015 POLARLED 36 OPTIMA CLAMP CONNECTOR CASE STUDY Nicholas Long FO&GT Subsea Technical Authority Ståle Størkersen Statoil ASA Advisor Pipeline Technology

2 POLARLED PROJECT:- The Polarled pipeline runs from Nyhamna Gas Terminal, some 500km north into the Norwegian Arctic Circle and terminates at a PLEM in 1,265m water depth near to the Aasta Hansteen SPAR Platform. The pipeline crosses many difficult terrains subsea including steep slopes and canyons. The project also has a design life of 50 years, this creates various design drivers that add additional requirements. This presentation discusses the following subjects:- Conventional clamp design (4) Design drivers for large bore clamp connectors (5) Large bore clamp connector design (6) State of technology for large bore clamp connectors (7) Large bore clamp connector operating & installation philosophy (8&9). (?) = References to section in paper Slide 2

3 Conventional Clamp Connector Design:- Clamp connectors typically have the same features:- i. Three clamp segments. ii. Single leadscrew operation. iii. Driven from API / ISO Drive Bucket. There are some significant issues when increasing size with conventional clamp connector design:- i. Scaling from smaller sizes is not practical. ii. How the clamp segments engage with the hubs, especially with pullin (misalignment) applications. iii. Single leadscrew and middle clamp segment movement. iv. Leadscrew design and load transfer. v. Application of torque to close clamp. vi. Sealring energisation load and section size. Slide 3

4 Design Drivers For Large Bore Clamp Connectors:- The design drivers for large bore clamps are:- i. Evening out clamping load from leadscrew. ii. iii. iv. Reducing relative clamp segment movement. Choice of leadscrew and trunnion thread form and material. Thread coefficient of friction. v. Torque application method into leadscrew. vi. Slender section sealring to reduce loads and size implications. A solution was needed that would take each of design drivers into account to address the issues with conventional clamp connector design. Slide 4

5 Large Bore Clamp Connector Design:- A design solution for the connector was created to give the best solution possible:- i. Change single leadscrew to twin leadscrew. ii. iii. iv. Change from 3 to 4 clamp segments. Fully assessed dedicated design (no scaling). Robust leadscrew thread form was selected. v. High strength CRA leadscrew & trunnions. vi. vii. Leadscrew torque application and direction of rotation. Leadscrew lubrication and coefficient of friction. To the right is a picture of the pre-paint assembled connector, which shows the twin leadscrew, four clamp segment design, that was a result of the changes listed above. Slide 5

6 State Of The Technology For Large Bore Clamp Connectors:- The Optima Connector for the Polarled Project was subjected to the following assessments and testing:- i. DMFECA according to DNV RP-A203. ii. Technology Readiness Level (TRL) & Categorization (TRC) Assessments. iii. Materials Criticality Assessment. iv. API-6A Annex F / ISO PR2 Testing(-20 C to +60 C, 0psig to 3,380psig). v. Total of 48off bend test cycles (60% SMYS pipe yield in 3 orientations). vi. 8off connector make & break cycles. vii. Reverse integrity test of sealring to leak point. The Optima connector performed perfectly under each of the tests. The leadscrew and trunnions had no visible degradation to the thread profile. The 36 Optima Clamp Connector for Polarled has achieved TRL5 Full scale technology built and integrated into the environment where it is intended to operate, with full interface and functionality tests. TRL6 will be achieved in Slide 6

7 Large Bore Clamp Connector Operating & Installation Philosophy:- The biggest benefit to the operating philosophy is the design change to twin leadscrew with 4 clamp segments. With two leadscrews, they can rotate in opposite directions. This counter rotating philosophy offers the following benefits:- i. Major reduction in clamp size and weight. ii. Closed loop torque reaction. iii. Elimination of torque reaction side loads. iv. Reduction in structural plate box size on clamp. v. Minimal porch / support structure. vi. Floating clamp for ease of maintenance (retrieval). vii. Reduced timescales during subsea ops. Due to the floating clamp design, this allows the clamp to move back exposing the hub face, offering:- i. Visual inspection by ROV for hub alignment. ii. Improved seal face cleaning and sealring removal / replacement operations. Slide 7

8 Large Bore Clamp Connector Operating & Installation Philosophy:- During installation, the following will apply:- i. Optima connector locked onto PLEM ii. Tooling located in tool basket. In emergency operations, the Optima connector can be retrieved on its own. Tooling uses fixed features on Optima. Once the PLEM has been installed on its structural skid base, the following operations can happen:- i. Optima Connector opened & moved back. ii. Hub cleaned and Duoseal installed. iii. PLEM is moved into place to close hubs. iv. Optima connector moved forward. v. Optima connector closed. vi. Backseal test completed. vii. Tooling returned to tool basket. Key:- 1 = 36 Optima Clamp 2 = Male Hub & Duoseal Seal Ring 3 = Female Hub 4 = Guide Structure 5 = Axial Shift Tool 6 = Twin Torque Tool 7 = Seal Removal / Seal Face Cleaning Tool Slide 8

9 With a reduction in the size and weight of the equipment and the other benefits listed above, the overall through life costs of the equipment are also reduced. Closing Remarks:- With trend towards larger export pipe diameters and longer service life projects, reducing equipment size can offer significant benefits. By incorporating the design drivers previously mentioned, the following are some of the significant benefits:- i. Weight reductions for equipment. ii. Use of smaller installation vessels. iii. Improved reliability & maintainability. iv. Operational Speeds. v. Predictable, reliable performance by a good qualification process. Acknowledgements:- FO&GT would like to thank Statoil for their support / backing on the Polarled project equipment and also their permission for, and co-authoring of this paper. References:- SCC2014-DW-Conference Paper by David Winfield of FO&GT VI-PT Optima Hub FEA & Testing For A694-F65 Through Hardenability by N Long & I Smyth of FO&GT. VI-PT Qualification Procedure for Statoil Polarled Optima Connector Equipment. 13ABD71825 Rev. 0 Optima Connector Type Approval Certificate from Bureau Veritas UK. Slide 9

10 Thank You For Attending. Any Questions? Slide 10