Progress Reports: December 2006 June 2006 December 2005
COMPOSITE REPAIR METHODS FOR STEEL PIPES
OBJECTIVE: Assess currently available composite repair systems for steel pipes and their applicability and limitations in various repair scenarios. Use this assessment as a basis for developing methods to expand the applicability of composite repair systems for more demanding scenarios.
INTRODUCTION: Pipe repair currently available are used increase the hoop stress resistance of pipes that have that have suffered a thinning of the wall due to external corrosion. These repair systems can be applied while the pipe is in service (flowing) in service. Typical applications are for pipelines or flowlines risers that are rigidly attached to the legs of fixed platforms, as shown below.
Application is currently limited to situations where there is no leakage, at elevations above the splash zone, in areas where little bending is expected, and below the deck away from process equipment.
These repair systems will be reviewed to provide guidance regarding the applications to various repair situations, and to if such repair techniques can be improved or extended (e.g. different fiber wrap geometries to provide bending resistance, different fiber/epoxy systems to reduce concerns of the performance of the composite patch near the splash zone.
BENEFITS TO MMS & INDUSTRY: The assessment of currently available composite repair systems will provide MMS guidance regarding the expected effectiveness and safety of such repair systems. The development of concepts to extend and/or improve these repair methods would allow more cost effective pipe repair options
DEPLOYMENT OF RESULTS: The assessment of existing repair methods and practices would be documented in a report to the MMS, and that report could serve as a basis for MMS guidelines on the applicability of various repair scenarios. Concepts to extend and/or improve these repair methods would be documented and presented to the MMS and industry. The industry would be responsible for the final development and testing of any concepts to extend and/or improve composite repair techniques.
ANTICIPATED NUMBER OF PHASES: 1 (18 months)
PROJECT PLAN:Scope and Plan:
Task1 - Gather information on the current state-of -the-art of composite repair systems and practices from the literature and discussions with contractors.
Task 2 - Define anticipate loads (e.g. wave, thermal) on the risers, and determine the stresses that a repaired riser would have to be able to safely withstand.
Task 3 - Document the range of and limitations on the applicability of existing repair systems, and prepare interim report for MMS.Task 4 - Identify opportunities and concepts to improve or extend these systems to more demanding repair situations, and complete analytical design studies to develop improved wrap and/or materials (fibers, epoxies) for composite repairs.
Task 5 - Demonstrate the effectiveness of the concept(s) to improve/extend composite pipe repairs through limited small scale testing.
Task 6 – Prepare Final Report documenting project findings and results.
Anticipated Results and Deliverables:
Interim report (Task 3)
Final Report (Task 6)PRINCIPAL INVESTIGATORS AND OTHERS INVOLVED IN THE PROJECT:
PI’s: Dr. Ozden A. Ochoa
Others: Ph.D Candidate Chris Alexander
Date: December, 2006Project Title: Composite Repair Methods for Steel Pipes
MMS Project: 558 TO Number: 39300
Project PI: Ozden Ochoa
COTR: M. Else
Estimated Completion Date: 3/1/2007
Project Description:
Assess currently available composite repair options for steel pipes and subsequently develop methods to expand their applicability in more demanding scenarios.Progress:
The following tasks have been completed as of 11/2006:• Assessed the loads imparted to typical risers and conventional riser design
• Fabricated 8-inch diameter pipe test samples with simulated corrosion
• Oversaw testing program and installation of strain gages by Stress Engineering Services (SES) technicians
• Interfaced with manufacturers & coordinated schedules for installation & testingo Product B: Urethane-E-glass system
o Product C: Epoxy-carbon system
o Product D: Epoxy-E-glass system• Performed full-scale testing using SES facilities and staff integrating
o Internal pressure
o Tension
o Bending loads• Test results are summarized in Figures 1 -3
• Interfaced with MMS and PHMSA regulators and staff
• Completed preliminary economic and efficiency studies as part of the composite repair design process.Current efforts are focused on
i. Developing guidelines to be used by MMS in assessing use of composite materials in repairing risers
ii. Developing an optimized repair system based on design process, experimental findings, and computational models.
Figure 3 – Composite reinforcement data for combined internal pressure, tension,
and bending loading
Reports and Publications:
Assessing the Use of Composite Materials in Repairing and Reinforcing Offshore Riser Pipes, OTRC presentation by Chris Alexander – Stress Engineering Services Inc at the Regional Operations Technology Assessment Committee (ROTAC) Meeting of Minerals Management Service - Pacific OCS Region, September 19, 2006.
DATE: June 2006
Project Title: Composite Repair Methods for Steel Pipes
MMS Project: 558 TO Number: 39300
PI: Ozden Ochoa
COTR: S. Buffington
Estimated Completion Date: March 1, 2007
Project Description:
The primary purpose of this program is to assess the exiting technologies and practices of using composite materials to repair offshore corroded sections of risers above mean water level, and to explore improvements and extensions to the existing technologies. The project will include the technical evaluation and full-scale testing of existing repair systems under realistic loads. Finite element analyses will be completed to illustrate and assess the reinforcement provided by particular composite systems. Furthermore a hybrid glass-carbon fiber reinforcement system will be evaluated to as a means of providing a robust underwater repair system.Progress:
In a joint activity with Stress Engineering, plans are underway to evaluate realistic loads and develop a full-scale test program for existing repair systems. Manufacturers of various repair systems have been contacted, and many have shown interest in supporting and participating in the test program.The testing program and procedures are being developed. Riser application scenarios are being evaluated to develop a realistic set of test loads. Pipes (8-inch diameter) will be machined to simulate a corroded riser section, and various repair systems will be applied by the manufacturers to three test samples. These “repaired” riser sections will then be tested to failure under realistic loads that include
Internal pressure
Internal pressure + axial tension
Internal pressure + axial tension + bending.At present, the focus is primarily on finalizing the test matrix, ordering pipe, and fabricating the test samples work (minimum of 24 test samples). Testing is expected to begin in August.
Publications & Reports: None
DATE: December, 2005
Project Title: Composite Repair Methods for Steel Pipes
MMS Project: 558 TO Number: 39300
PI: Ozden Ochoa, MEEN
COTR: S. BuffingtonEstimated Completion Date: June 2007
Project Description:
Assess currently available composite repair options for steel pipes and subsequently develop methods to expand their applicability in more demanding scenarios.
Progress:
Task 1-gathering information on the current state-of -the-art of composite repair systems and practices from the literature is completed. At this stage, composite wrap of hoop windings is the accepted norm which only addresses strengthening for pressurization and possibly leak prevention. The discussion with field operators and contractors are next to be engaged to narrow done the pipe diameter and thickness for the current study.
Task 2 - define anticipate loads (e.g. wave, thermal, mechanical) on typical risers are completed. The splash zone environmental concerns (chemical composition of sprays and gasses are to be defined next. The methodology to obtain the profile of axial, bending and hoop stresses in damaged pipes are now in place and will be exercised once the geometry of the repaired section is clearly defined with MMS concurrence.
Task 3 - Currently the emphasis is on this Phase. Documenting the range of and limitations on the applicability of existing composite sleeve systems, and prepare a preliminary report for MMS in order to hold a small meeting in mid May to assure these parameters are selected with industrial ( invited oil exploration and production principals including repair technology businesses such as Armor Plate, Clock Spring, RiserClad) and regulatory MMS feedback.
Publications & Reports: None
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