Scaling and Self-Sensing in Composite Repairs of Corrosion Defects

The goal of the research presented in this report is to characterize two approaches for installing composite repairs intended for pressure equipment. Currently, the accepted composite pipeline repair is a full-encirclement repair installed in a continuous layer around the damaged region. The research presented in this report examines the performance of a discontinuous patch repair in lieu of a full-encirclement repair. The performance of these two repair types is examined by pressure fatigue testing on straight pipe samples of 6-inch nominal diameter. A 75% wall loss defect was machined into each sample to simulate external corrosion damage. Pressure was then cycled from 0 to maximum allowable operating pressure (MAOP) until either failure or runout of 100,000 cycles was reached. Fatigue lives and substrate strain levels are compared for the full-encirclement repairs and patch repairs. The average fatigue life for the full-encirclement repairs is 13,261 cycles with a standard deviation of 10,205 cycles while the patch repairs exhibited an average fatigue life of 51,852 cycles with a standard deviation of 42,363 cycles. Of the 18 samples tested, 9 were patch repairs and 9 were full-encirclement repairs. All full encirclement repairs exhibited a fatigue life less than 27,000 cycles. For patch repairs, 4 specimens reached runout of 100,000 cycles. The strain response of the full-encirclement and patch repairs indicated that at the beginning of fatigue cycling the patch repairs exhibited a larger strain in critical areas; however, at the end of fatigue life, the full-encirclement repairs exhibited a larger strain in the same critical areas. After the small-scale tests were completed, a large-scale vessel test was initiated. Patch repairs of the same design were installed on a 42-inch vessel and cycled from 80 psi to 500 psi. The maximum pressure level was chosen to match the in-plane stresses present in the small-scale specimens. Based on the fatigue testing presented in this work, patch repairs are a viable solution for repairing pressure vessels and piping with external corrosion defects. Additionally, current results indicate that testing of repairs on small scale specimens is sufficient to determine repair success on larger scale pipe and pressure equipment.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Bibliography; Figures; Photos; Tables;
  • Pagination: 72p

Subject/Index Terms

Filing Info

  • Accession Number: 01638912
  • Record Type: Publication
  • Contract Numbers: DTPH56-13-H-CAAP02
  • Files: TRIS, ATRI, USDOT
  • Created Date: Jun 13 2017 8:56AM