High Temperature Hydrogen Attack Resistance Using ... · PDF fileHigh Temperature Hydrogen...
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High Temperature Hydrogen Attack Resistance Using Autoclave Testing of Scoop SamplesSM
Tim Munsterman Antonio Seijas Dana G. Williams, P.E. Technology Director –
Engineering. Mechanical
Engineering Consultant Materials & Corrosion Specialist
Lloyd’s Register Capstone, Inc. Marathon Petroleum Co, LLC Houston, Texas USA Ashland, Kentucky USA
Presented by:
Dr John Fuad Edwards
Haed of Integrity Services
Lloyd’s Register
Kuala Lumpur
March 6-8 2012
API Singapore 2012
• Introduction • Industry Dilemma • Scoop SamplerSM • Autoclave Testing • Real Time Monitoring • Data Interpretation • Conclusions
March 6-8 2012
API Singapore 2012
Introduction API 941 High Temperature Hydrogen Attack curves.
• 1976 Guard Reactor in a Distillate Hydrotreater Unit
• A302-B C-Mn- ½Mo Steel • Operating 110C (230oF) above CS
Curve • High Potential for HTHA based on
API 581 Risk Based Inspection • No damage found so far, however,
limited prior inspections • Scoop Sample Removal for
Toughness Testing and HTHA Testing
Carbon Steel Curve
C ½ Mo Curve
100 Hr Curve
Test Conditions
4H + FeC↔CH4 + Fe (atomic hydrogen reacting with iron carbides)
March 6-8 2012
API Singapore 2012
Industry Dilemma: How to tell Good from Bad C ½ Mo Steel?
• Microstructure analysis not reliable for HTHA resistance. • Current HTHA models incorporate range of HTHA Susceptibility,
Probability or Carbon Activity • There is no method to measure Carbon Activity • Actual HTHA Resistance Is Not Known • LR Capstone Approach is Straightforward:
• Perform a Test Using Vessel Material to Determine Properties • Similar Concept to Accelerated Creep Testing • Elevated Temperatures and Pressures using H2
• Remove Samples From Vessel • LR Capstone’s Scoop SamplerSM • Various Plates / Locations
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API Singapore 2012
Scoop SamplerSM
• Removes a spherical shaped samples – low stress concentration
• Attach tool using magnets • Uses a spherical cold cut saw blade
– no sparks • Local thin area calculations
performed prior to avoid repair welding
• Toughness can only be measured destructively
• Quantitative HTHA Resistance • Over 500 Scoop Samples Removed
March 6-8 2012
API Singapore 2012
Scoop Sample Locations – Guard Reactor
Lower Course
Top Head
Bottom Head
Upper Course
Scoop Sample 1
Scoop Sample 4
Scoop Sample 8
Scoop Sample 10
Scoop Sample 3
Scoop Sample 7
Scoop Sample 2
Scoop Sample 9
Scoop Samples 5
and 6
Impact Testing
Scoop Samples 11 and 12
HTHA Testing
• Performed both: • MPT Assessment
(Minimum Pressurization Temperature)
• HTHA Assessment • Samples removed from each shell
course and head (bottom head was not accessible at time of testing)
• Weld metal and HAZ’s included. • Nozzles can be sampled.
March 6-8 2012
API Singapore 2012
Scoop Samples Removed from Guard Reactor
March 6-8 2012
API Singapore 2012
High Temperature Hydrogen Autoclaves
97 bara H2 538°C
March 6-8 2012
API Singapore 2012
Full Immersion Coupon for Real Time Incipient Damage Monitoring
• 0.25” diameter x 0.375 long
March 6-8 2012
API Singapore 2012
Immersion Coupon Microstructure After Testing Displacement Monitoring of Coupon HTHA Swelling
• Hydrogen reacts with carbon to form methane.
• Methane trapped sub surface
• Intergranular methane bubbles (voids) and cracking
• Coupon swells with damage.
• Incipient damage when rate is non- linear
March 6-8 2012
API Singapore 2012
Carbon Steel Reference Coupon
• Displacement data is continuously monitored during HTHA testing
• Change in rate indicates incipient threshold
• Test duration based on time to incipient damage
March 6-8 2012
API Singapore 2012
C ½ Mo Coupon from Scoop Sample 11 (Upper Course)
• Displacement data showed growth during entire HTHA test
• Change in rate indicated incipient threshold
• Similar to a shift from second to third stage creep
March 6-8 2012
API Singapore 2012
• Displacement data indicated continuous growth during HTHA testing
• Change in rate indicated incipient threshold
• Jump in displacement likely due to blister formation
C ½ Mo Coupon from Scoop Sample 9 (Top Head)
March 6-8 2012
API Singapore 2012
• Surface Exposed to H2
• Large blister at center of coupon
• Many smaller blisters • Cross sectioned this
coupon for depth of damage
C ½ Mo Coupon from Scoop Sample 6 (Lower Course) Single Side Exposure - 830 Hours
March 6-8 2012
API Singapore 2012
• One side exposure coupon
• Cross section view for depth of damage
• 39.5% through-wall damage
• High Resistance to HTHA
C ½ Mo Coupon from Scoop Sample 6 (Lower Course)
Single Side Exposure - 830 Hours
March 6-8 2012
API Singapore 2012
• Cross section view for depth of damage
• 75% Through Wall HTHA Damage
• Incipient Damage Occurred in 10 Hours.
Carbon Steel Ref. Coupon
Single Side Exposure - 181 Hours
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API Singapore 2012
• Cross section view for depth of damage
• 7.4% Through Wall HTHA Damage
• Incipient Damage Occurred in 151 Hours.
Scoop Sample 5 C ½Mo Coupon
Single Side Exposure - 181 Hours
March 6-8 2012
API Singapore 2012
Data Interpretation • API 941 Incipient Damage Curves • Better Approach: The Pw parameter
• Amount of time to incipient damage • First developed by Shewmon • Refined by Japan Pressure Vessel Research Council (JPVRC) • Included in the Technical Basis for 941 Report, Appendix F
Pw= - 3 ln(PH2)-ln(t)+190000/(8.3145 T) Where: PH2 = hydrogen partial pressure in MPa,
t = time in hours, T= temperature in K
March 6-8 2012
API Singapore 2012
HTHA Test Results with Pw Calculations
Test Samples T, °C P, bara Hours to Incipient Damage
API 941 App. A-1
Critical Pw 20 yr
No Attack
Pw Calculated
Projected Years to
Increase in Risk
Carbon Steel (516-70) Sample 545 97 10 ----
Scoop Sample# 11 (Upper Course) 544 97 110 16.43 110
Scoop Sample# 5 (Lower Course) 538 97 151 16.33
Sample# 9 (Top Head) 538 97 159 16.28
Scoop Sample# 6 (Lower Course) 538 97 232 15.90
C ½ Mo Current Op. Conditions 402 34 17.75 30
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Conclusions • Reactor has similar or better resistance than “good” C
½ Mo steel • Reactor is suitable for this service • Reactor will move to a medium potential for HTHA
damage after 30 years of operation. • It is recommended to perform HTHA inspections
based on risk based guidelines given in API 581 or similar.
March 6-8 2012
API Singapore 2012
Conclusions • The upper course and top head displayed lower HTHA
resistance • Recommended more thorough inspections of these
plates and fewer locations on the lower course • Typical RBI assessment for a C ½ Mo vessel
operating 110°C (230oF) above the carbon steel curve: • High likelihood after just 250 hours of exposure
(based on API 581, Appendix I, Table I-3).
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Thank you for listening
For more information: Tim Munsterman Phone 1-281-649-2212 Mobile 1-281-414-2136 Fax 1-281-493-5161 Engineering Services Lloyd’s Register Capstone, Inc. 1505 Highway 6 South Suite 100 Houston, TX 77077 [email protected] www.lr.org