Product Design and Qualification (Validation) TestingforHPHT Systems • 2010
HPHT Design Design Performance Test Materials 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? 2
Proposed PER15K Yes FAD , S-N low /infinite No 3
HPHT Design Design Performance Test Materials 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… 4
Bolt Loading Hoop Stress Energized Force HPHT Design Crush contact of BX Gasket Design Performance Test Materials High Contact Compressive Stress 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 PL-M = Temp (log tr +C) Larson-Miller Regression Curve Thermal FEA plot illustrating an example of insulating the body while keeping an adjacent component (actuator) uninsulated to optimize seal use From API TR 6J1 5
Over complicating H2S Failure to Fast Fracture K1Scc Elevated temperature probably increases crack growth rate / shortens design life Assumed flaw size detectable at factory during manufacture
HPHT Design Design Performance Test Materials HPHT Designer Issues • Need to establish appropriate HPHT performance validation testing to prove FEA • Is one needed for fracture mechanics? 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
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
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.
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
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.