Crack Reinforcement Using the Pipestream XHab TM Repair System

Transcription

1 Crack Reinforcement Using the Pipestream XHab TM Repair System Third Annual Composite Repair Users Group Workshop Hilton Garden Inn NW America Plaza (Houston, Texas) Thursday, September 26, 2013 Prepared by Colton Sheets and Chris Alexander Presentation by Chris Alexander

2 Presentation Overview Project Overview Pipe Sample Details Crack Growth Monitoring Phase 1 Testing Sample details Test results Phase 2 Testing Sample details Test results Summary Slide 2

3 Project Overview The purpose of the test program was to evaluate the repair of cracks in pipelines using Pipestream s XHab TM composite repair system. The project consisted of two phases. Phase 1: Six (6) sample pipes subjected to burst and cyclic pressure testing. Phase 2: Five (5) samples which were subjected to cyclic pressure testing. Each pipe had axially-aligned EDM planar flaws. Cyclic pressure used to grow cracks in EDM planar flaws prior to the repair installation. Slide 3

4 Slide 4 Pipe Sample Details

5 Crack Monitoring Strain Gage on Sample Notch Clip Gage on Sample Notch Slide 5

6 Crack Growth Monitoring Phase 2 - Sample 1 Failure at 1,602 cycles Slide 6 *Note: Recording of displacement was stopped prior to failure in order to protect clip gages

7 Crack Propagation Phase 1 This macrograph validates that after 1,600 pressure cycles a crack generated at the base of the gouge. Help establish 1,265 pre-cycle condition. Slide 7

8 Phase 1 Sample Details Phase 1 Sample Gage Type Pre-cycling Repair Post Cycling Test Type 1 N/A Y N None 2 N/A Y N None 3 SG Y Y Cycle 4 CG Y Y Cycle 5 CG Y Y Burst 6 SG Y N Burst Samples 1 and 2 were pressure cycled at ΔP=100 psi to 890 psi until failure occurred in order to characterize crack growth Samples 3 through 6 were pre-cycled prior to final burst and pressure cycling in order to initiate crack growth from EDM notches. Strain Gages (SG) and Clip Gages (CG) monitored crack growth The repair thickness was approximately 3mm Slide 8

9 Phase 1 Burst Test Results Sample Repaired Max. Pressure (psi) 5 Y 1,835 6 N 1,138 Sample 5 Following Burst Slide 9

10 Cyclic Pressure Testing Phase 1 Samples 3 and 4 were pressure cycled from 100 psi to 890 psi. The samples were cycled for 170,000 cycles in addition to the 1,200 cycles completed during pre-cycling no failures. Slide 10

11 Cyclic Pressure Test Results Phase 1 Sample Repaired Max. Number of Cycles 1 N 1,638 2 N 1,526 3 Y 170,000* 4 Y 170,000* *Cycles stopped prior to failure No significant increase in strain range or maximum strain for either sample over the course of cycling Gages located on pipe beneath repair Slide 11

12 Phase 2 Testing Work Phase 2 Phase 1 proved to be successful, but concerns existed over repair being too thick. Phase 2 work initiated to address the effects of reinforcement thickness on fatigue performance. New pipe material purchased, so additional testing required to establish fatigue life of unreinforced samples and establish pre-cycle condition. Slide 12

13 Phase 2 Sample Details Phase 2 Sample Gage Type Pre-Cycled Repaired Post-Cycling Test Type 1 CG/SG Y N None 3 CG/SG Y Y Cycle 4 CG/SG Y Y Cycle 5 CG/SG Y Y Cycle 6 CG/SG Y Y Cycle Five (5) samples were pressure cycle tested One (1) sample was unrepaired and cycled to failure. Remaining four (4) samples were pre-cycled, then repaired, and finally pressure cycled until failure. Pressure cycling of the samples was from 100 psi to 890 psi The thickness of the reinforcement varied. Slide 13

14 Cyclic Pressure Testing Phase 2 Sample Repaired Max. Number of Cycles 1 N 1,602 3 Y 4,879 4 Y 13,436 5 Y 114,851 6 Y 14,188 Repaired samples showed at a minimum a 3x increase in the number of cycles to failure Slide 14

15 Summary of Fatigue Lives Phases 1 and 2 Sample #F1U Sample PSP1-2UF Sample PSP2-1UF Sample PSP2-3RF Sample PSP2-4RF Sample PSP2-6RF Sample PSP2-5RF Sample #F4R Sample #F6R 1,638 cycles (no repair) 1,526 cycles (no repair) 1,602 cycles (no repair) 6,144 cycles (1 mm thick repair installed at 300 psi) 14,611 cycles (1 mm thick repair) 15,453 cycles (1 mm thick repair) 116,116 cycles (2 mm thick repair) 237,435 cycles (3 mm thick repair) no failure 237,435 cycles (3 mm thick repair) no failure Notes: 1. Standard deviation among unrepaired samples was 57 psi; Coefficient of Variation of 3.6%. 2. All repaired fatigue lives include 1,265 applied pre-cycles. Slide 15

16 Project Summary Effective means established for generating extremely consistent crack-like flaws. Very tight scatter among similar test samples. Repaired burst samples had failure pressures on the order of 150% SMYS. Clear correlation between reinforcement thickness and increase in fatigue life. Planar flaws were extreme in that most operators would not repair a 50% deep crack-like flaw. Slide 16

17 Questions? Dr. Chris Alexander, P.E., Principal (281) (direct) Slide 17