Product Design and Qualification
(Validation) Testing
for
HPHT Systems
2010
HPHT Designer Issues
HPHT
Design
•
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
Basis of
Design
Functional
Design
Specification
Design
Equipment &
Documentation
Yes
FAD , S-N
low /infinite
No
Design
Verification
Design
Validation
Design
Meets FDS
Production
3
HPHT Designer Issues
HPHT
Design
•
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
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
HPHT
Design
Bolt
Loading
Thermal FEA plot illustrating an example
of insulating the body while keeping an adjacent
component (actuator) uninsulated to optimize seal use
PL-M = Temp (log tr +C)
Hoop
Stress
Energized
Force
Crush
contact
of BX
Gasket
High Contact
Compressive
Stress
Larson-Miller Regression Curve
From API TR 6J1
5
Over complicating H2S Failure to Fast
Fracture
Elevated temperature probably
increases crack growth rate /
shortens design life
K1Scc
Assumed flaw size
detectable at factory during
manufacture
6
HPHT Designer Issues
HPHT
Design
•
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
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
12
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.
14
ASME Cycle Count
15
Higher Level of Qualification Testing
16