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Document Sample
Fatigue Performance of High
Strength Riser Materials
RPSEA Project No. DW 1403
TAC Meeting
March 3, 2009
Houston, Texas
Presented by
Stephen J. Hudak, Jr.
Materials Engineering Department
Southwest Research Institute
Research Partnership to Secure Energy for America
1
Background and Motivation
Quest for offshore O&G leading to deeper
water, increased temp. & pressure
These conditions preclude the use of
conventional riser materials
New higher strength materials are needed
The fatigue resistance of new materials is
unknown, particularly in aggressive
environments
2
Project Objective
Assess the fatigue resistance of new
high strength HPHT riser materials in
representative environments
3
Project Benefits
Results on corrosion-fatigue
resistance of new materials will:
• Decrease development time
• Reduce technical risks
• Enable optimum material selection
• Provide the basis for fatigue design of light-
weight HPHT risers
• Enable NDE requirements to be set
• Enable feasibility of more deepwater
development projects
4
Project Tasks
Task 1: Fatigue Crack Growth Rate
(FCGR) Testing
Task 2: S-N Fatigue Life Testing
Task 3: Recommended Phase 2 Work
Task 4: Program Management,
Tech. Transfer and Reporting
5
RPSEA PM
RPSEA PM
Jim Chitwood
Jim Chitwood
Chevron
Chevron
Industry
RPSEA PM
Working Committee
Project Team Jim
Himanshu Gupta, BP
Steven Shademan, BP
Chitwood
(Champions)
Chevron
SwRI®®PM
SwRI PM
Steve Hudak
Steve Hudak
Task 0:
Task 0: Task 1:
Task 0: Task 2:
Task 0: Task 3:
Task 0: Task 4: 0:
Task PM
Spec Design
Spec Design FCGR
Spec Design S-N
Spec Design Phase 2
Spec Design Spec Trans,
Tech Design
and Prep
and Prep and Prep
and Prep Fatigue
and Prep Plan
and Prep Reporting
and Prep
Jason
Jason Jim
Jason Wally
Jason Steve
Jason Steve
Jason
Patton
Patton Feiger
Patton Robledo
Patton Hudak
Patton Hudak
Patton
6
Materials
Supplier Material Selection Rationale
Sumitomo C110 Highest strength steel with
sour resistance
Sumitomo C125 Highest strength steel, but
sour resistance unknown
V&M C125SS Highest strength steel, but
sour resistance unknown
Sumitomo Q125 Highest strength material for
non-sour applications
Sumitomo 140G Potential for non-sour service,
but little data available
RTI Ti-Gr29 Ti-alloy of choice to compare
against high-strength steels
7
Environments
Lab air (baseline): 70-75°F, 40-60% RH
Seawater: ASTM D1141 substitute ocean
water open to the air with cathodic
protection: - 1050mv vs. Saturated
Calomel electrode
Sour Brine: Production brine with oxygen
below 10 ppb and 35% H2S + 65% CO2
8
Task 1: FCGR Testing
Frequency scan (FS) tests at Constant-DK
to determine optimum cyclic loading
frequency for subsequent testing
FCGR testing as a function of DK to
determine cracking kinetics that can be
used in fracture mechanics design and/or
fitness-for-service assessments
9
FCGR Specimen
10
Task 1: FCGR Test Matrix
Material Air Seawater Plus Sour Brine Applications
Material Strength Tests CP Tests Tests Targeted
6 Ti-Gr 29 (data available) (data available) 2 SCR, Hybrids,
plus 1-f scan Dry tree
1 110 ksi 2 2 2 Inner Casing,
plus 1 f-scan plus 1-f scan SCR, Hybrid
2 125 ksi 2 2 2 Outer, Inner Casing,
plus 1 f-scan plus 1-f scan SCR, Hybrid
3 125 ksi 2 2 2 Outer, inner Casing,
plus 1-f scan plus 1 f-scan SCR, Hybrid
4 125 ksi 2 2 Outer Casing, Non-
plus 1-f scan Sour SCR/ Hybrid
5 140 ksi 2 2 Outer Casing, Non
plus 1-f scan Sour SCR/ Hybrid
Total FCGR tests 10 15 9+3 Grand Total: 34+3
Red tests not in current SOW
11
Frequency Scan Testing
Corrosion fatigue
performance highly
dependent on
loading frequency
X65 Steel
Fatigue crack
growth rates at
constant-DK used
to characterize
frequency effect in
frequency scan (FS)
tests
12
Effect of Sour Brine
on FCGR vs. DK in X65 Steel
10-3
blue symbols - Air
red symbols - H2S
invalid
10-4
da/dN (in /cycle)
10-5
invalid
10-6
10-7 Test 603U-C3
Test 603U-C2
5 10 100
DK (ksiin)
13
Task 2: S-N Fatigue Life Testing
Use full-thickness strip specimens cut
from pipes
Use optimum frequency determined in
Task 1
Target Lives: 1,000s to 1,000,000 cycles
(depending on loading frequency)
14
S-N Strip Specimen
15
Task 2: S-N Fatigue Test Matrix
Material Strength Air Seawater Plus Sour Brine Applications
Designation Level Tests CP Tests Tests Targeted
6 Ti-Gr 29 (data available) (data available) 8 SCR, Hybrids,
Dry tree
1 110 8 8 8 Inner Casing,
SCR, Hybrid
2 125 8 8 8 Outer, Inner
Casing,
SCR, Hybrid
3 125 8 8 8 Outer Casing, Non
Sour SCR, Hybrid
4 125 8 8 Outer Casing, Non
Sour SCR/ Hybrid
5 140 8 8 Outer Casing, Non
Sour SCR/ Hybrid
Total S-N tests: 40 40 24 + 8 Grand Total: 104 + 8
Red tests not in current SOW
16
Sour S-N Results
on Conventional (X65) Steels
1000 0.01Hz
Env. B
0.6%H2S
Local Stress Range, MPa
pH=4.1
Class E Mean
1-day test
in-air re-tested
0.01Hz
Env. A
6%H2S
pH=3.5 0.01Hz re-tested
Env. A
100 6%H2S 0.33Hz
2.4%H2S 0.5Hz
pH=3.5
pH=3.5 Env. B
McMaster '07
Buitrago '02 0.6%H2S
pH=4.1
1.0Hz
Env. A
6%H2S
pH=3.5
LCF ICF HCF
9-month test
10
1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08
Endurance, Cycles
17
Task 4:Technology Transfer
Project Working Committee (PWC) established
Frequent communications with the PWC and
RPSEA PM
TAC Quarterly Presentations
TAC Final Presentation
Distribute reports and data to PWC
Publications:
• OMAE Conf. Proceedings
• Industry Journal article
18
Costs
Task 0: Spec. Design/Prep: $161K
Task 1: FCGR Testing: $191K
Task 2: S-N Testing: $409K
Task 3: Phase 2 Plan: $30K
Task 4: PM, TT, Reporting: $209K
Total Cost $1,000K
BP Cost Share $200K
RPSEA Funding $800K
19
RPSEA Schedule
Schedule
Schedule in Months
Task Activity 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
D J F M A M J J A S O N D J F M A M J J A S O N
0. Spec Design/Prep Mat Proc+Spec Prep
1. FCGR Testing Freq Scan
Air
SW+CP
Sour
2. S-N Fatigue Air
SW+CP
Sour
3. Phase 2 Plan
4. Program Mgt.
Deliverables 20
Schedule Assumptions
Freq. scan ave. duration: 2 mo./test
Air ave. test duration: 0.5 mo./test
SW+CP ave. duration: 1 mo./test
Sour brine ave. duration: 1 mo./test
FCGR testing: 4-5 machines/ 15 mo.
S-N testing: 5 machines/22 mo.
21
Programmatic Issues
Schedule depends on test durations which
depend on results of Task 1 freq. Scans
Considering outsourcing more of the less
complex tests to maintain or shorten
schedule e.g. SW+CP tests
Outsourcing will require RPSEA/DOE
approval
22
Project Status
Contract signed: Dec 15, 2008
Progress after 2.5 months:
• Admin. Kick-off telecom held Jan. 8
• Tech. Kick-off meeting held Jan 16
• Three of six materials procured -- at no cost to the project
• Arranged for ConocoPhillips to donate Ti-alloy data base
• S-N and FCGR specimens designed
• FCGR specimens machined for materials in hand
• Frequency-scan tests underway
• 40% of S-N specimens machined for material in hand
• 11 new fatigue tests in sour brine identified
• Cost of new tests offset by arranging for NETL-Albany to do
baseline air tests in initial plan
• Considering additional outsourcing to reduce schedule
23
Plan for Next Quarter
Take delivery of remaining materials
Machine remaining specimens
Complete 80% of freq. scan tests
Machine grips and provide to NETL
Initiate air S-N tests at NETL
Initiate interlab. S-N test program (SwRI vs. NETL)
Make decision on outsourcing seawater tests
If needed, procure potentiostats for CP tests in
seawater
If needed, prepare chambers for seawater tests
24
