Product Design and Qualification (Validation) Testingfor
HPHT Systems
2010
HPHT Designer Issues
• Design Methodology much more rigorous FEA and Fracture Mech.
• No clear definition of Material Properties needed for FEA and Fracture Mech.
• Need to establish appropriate HPHT performance validation testing to prove FEA– Is one needed for fracture
mechanics?
HPHTDesign
Mat
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Design
Performance Test
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Basis of Design
Design Equipment &
Documentation
Design Meets FDS
Design Verification
Design Validation
Production
Functional Design
Specification
3
Proposed PER15K
FAD , S-N low /infinite
No
Yes
HPHT Designer Issues
• Design Methodology much more rigorous FEA and Fracture Mech.– FEA, Thermal, – FAD – BS 7910 DnV C203, API 579– Should be limited to pressure
containing, pressure controlling, seals, and fasteners…
HPHTDesign
Mat
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Design
Performance Test
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HPHT Designer Issues• Much work remaining with
respect to materials– Metallic properties derating,
thermal growth, da/dN, K1Scc – ASME, API 6AF1 – Seals, fasteners need creep or
stress relaxation (DMM) for life expectancy
– Thermal FEA to justify temperature zone use?
– Non-metalics life expectancy tests
HPHTDesign
Mat
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Design
Performance Test
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Crush contact of BX
Gasket
Bolt Loading
Hoop Stress
Energized Force
High Contact Compressive
Stress
PL-M = Temp (log tr +C)
Larson-Miller Regression CurveFrom API TR 6J1
Thermal FEA plot illustrating an exampleof insulating the body while keeping an adjacent
component (actuator) uninsulated to optimize seal use
6
Over complicating H2S Failure to Fast Fracture
Assumed flaw size detectable at factory during
manufacture
Elevated temperature probably increases crack growth rate /
shortens design life
K1Scc
HPHT Designer Issues
• Need to establish appropriate HPHT performance validation testing to prove FEA– Is one needed for fracture
mechanics?
HPHTDesign
Mat
eria
ls
Design
Performance Test
7
Background / History / Needs Assessment• Recognition that current industry standards are not
specific in addressing the requirements for seals therefore it is left to the equipment manufacturer/user to determine applicability of the requirements/standardized tests
• Procedures that are typically used (eg. API 6A PR2 Annex F) are not satisfactory to provide product designs with proven, long term reliability– Short term tests do not expose product weaknesses– Same test scenario regardless of type of product or
environment– Separate testing for material and product– Material testing typically only covers compatibility with the
environment but lacks stressed induced failure mechanisms that directly apply to the product design
8
Goals for Improved Testing / Qualification Program
• Develop protocols / methodology that will provide a better indication of the of the long term performance of a product / design
• Educate the industry on the benefits of more rigorous testing methods
• Develop measurements/codes/processes/product markings to ensure that products that are tested are in conformance to the requirements
9
Current PR-2 Verification Process• API 6A Appendix F does not specifically state any
requirement for the verification of metallic seals.• FMC requires that metallic seals be verified to the
same requirements as wellhead equipment, connectors and fittings.
• API 6A, Appendix F requires that wellhead equipment, connectors and fitting be subjected to three temperature cycles. Each temperature cycle starts at ambient temperature, heats the equipment to the maximum rated temperature, cools the equipment to the minimum rated temperature and then brings the equipment back to the ambient temperature. At the maximum and minimum rated temperature, the equipment is pressured to the maximum rated pressure and held for one hour, while checking for leakage. 10
API 6A, Annex F, PR-2
11
API 17D (FDIS) – New Additions• New draft brings seals up
to same testing cycle as valves and connectors
• New draft has an Annex J for fluid compatibility
• New draft has Annex L for hyperbaric (external) pressure tests
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13
Proposed PR-3 Test Philosophy• HPHT pressure containing, pressure controlling and seals
have many characteristics which need to be studied in greater detail than API 6A, Appendix F, PR2 addresses.
• Material properties which can be affected during HPHT exposure include, but are not limited to, wear, galling, fatigue, stress relaxation, corrosion, and exposure to sand or grit.
• Material properties “weaken” at elevated temperatures– Option 1 - Possible higher test pressure at ambient temperature needs
to be addressed properly stress components, or– Option 2 - Consider cycle testing of pressure and temperature in
tandem.• Additional endurance test criteria which needs to be
discussed includes the addition of make-and-break cycles, additional temperature/pressure cycles, and confirmation testing of seal designs.
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ASME Cycle Count
15
Higher Level of Qualification Testing
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