Item 06 - API 17 Subsea HPHT Discussion

API 17 – Subsea HPHT Discussion
PER 15K : “… should be used as a guide by the various
API Subcommittees to develop future documents on
equipment specifications for HPHT service. This report
is not intended to replace existing API equipment
specifications. … intended to illustrate accepted
practices and principles that may be considered…”
• Design Methodology has been in review and development for 5+ years and relies
on ASME BPVC, Section VIII, Division 2 or 3.
– But no clear guidance when/where to switch from Div 2 – “Thin wall” to Div 3
– “Fracture Mech.”
• No industry (operator) guidance on Validation Testing.
– What constitutes “acceptance”? Is it Annex F or something tied to fatigue
life/fracture mechanics?
• Material Properties for pressure containing and pressure controlling components
showing clarity on what’s needed in last 2 years.
– But no data on material ‘s HPHT properties published for widespread use.
– No clear path yet on seal technology.
Elastic vs.
Most agree that for HPHT,
E-P or Load-Limit + FAD
(fracture mechanics) is way
to go. The question: When
do we switch?
The question: How do we
balance between 6A
which has 20k and 350
and 17D which has 15k
and 350?
Validation Testing
The question: When is Annex F testing is no longer valid? Is
Annex F only valid for elastic design / functional testing?
What level of testing is desired when fatigue design life is
Materials Issues
Main material use groups for HPHT
Pressure Containing
Pressure controlling
What pressure containing/controlling
properties need to be met?
Tensile, Yield, modulus @ elevated
Tensile/yield ratio
da/dn @ temperature & environment
K1C, J1C, K1SCC for ranking
Fatigue life at temperature
Affect of cathodic protection - hydrogen
Seals - creep resistance
Fasteners - stress relaxation

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