industry standards – a blessing or a...
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Industry standards – a blessing or a curse?
Alexandra Torgersen NGF Høstmøte 2013 2013-ATE-PN-104
Special challenges facing soft seal solutions
Floating Production Storage & Offloading Vessels
Turret Mooring Systems
Tension Leg Platforms
Light Well Intervention
Guidelineless Deepwater Trees
Subsea Manifold Smart Well
Control Systems Subsea Template Systems
Standard Subsea Trees
Metering & Control Systems
Surface Well Systems
ROV Tie-In Systems
Subsea Processing
Subsea Drilling Systems
Oilfield equipment
Production environments
• Subsea production: Seals, gaskets, packoffs, connectors, diaphragms.
• Temperatures from - 50 oC to 180 oC possible. Pressures up to 1,000 bar differential.
• Resistance to production/injection fluids, gases, chemicals, acids.
• Mechanical abuse is less than drilling.
• Subsea applications are very critical due to cost (millions of $) and environmental issues.
• Service life of 20 to 30 years or more.
Failure mechanisms
• Mechanical • Extrusion • Chemical • RGD
Industry requirements
What is the basis for industry standards?
• Common minimum requirements for specific equipment
• Collective industry knowhow and understanding
• Eliminate common mistakes/challenges • Guide to ensure fit form and function
Why do we need them?
• Alternative is every company making their own rules
• Assist and guide newcomers to understand challenges in industry
• Assist and guide everyone deliver equipment that works
Do the standards cover everything?
10
Offshore development
©Statoil
Wells/Downhole equipment Material Selection Fabrication Fatigue High temperature
Flowlines Material Selection Plastic deformation High temperature Corrosion inhibitors CP Coating
Risers Material Selection Fabrication Fatigue
Export pipelines Fabrication Running fracture
Hull Fabrication CP/ coating
Topsides Material Selection Coating
Subsea XT and TM Material Selection Fabrication Fatigue High temperature CP/ Coating HISC
Drilling/ Workover Material Selection Fabrication Fatigue
ISO 13628/API 17 ISO 10423/API 6A
DNV OS-F101 DNV OS-F101
DNV OS-F201
NORSOK
NORSOK/ISO/API
DNV DNV Class Rules
Typical subsea industry elastomer testing philosophy
• Production system: all seals typically qualified per NORSOK M710, ISO23936, and ISO10423 (API 6A)
• Hydraulic system: many seals accepted as field proven. ISO 13628-6 covers materials testing.
• Chemical injection system: primarily metal seals or thermoplastic seals (PEEK, PTFE) which have very high chemical resistance. Elastomers typically tested (immersion testing). No specific industry standards, but can be covered using NORSOK M710, ISO 23936. Often ISO 1817 is used.
• Completion fluids: exposed seals tested (immersion testing) in completion brines. No specific industry standards, but can be covered using NORSOK M710, ISO 23936. Often ISO 1817 is used.
Industry standards • Subsea production seals:
– NORSOK M710 – ISO 23936 – ISO 10423 / API 6A
• Subsea hydraulic fluid seals: – ISO 13628 part 6
• Downhole seals: – ISO 13533 – ISO 16070 – ISO 14310
• General: – ISO 1817
NORSOK M710 –production fluid seals
• Scope: production seals – Seals wetted by production fluid
• Provides methodology for qualification of materials and manufacturers
• QC requirements • Material standard only, no functional
requirements or testing
NORSOK M710 – Service life prediction
• Methodology: – 3 test temperatures – Durations long enough to achieve >50% drop in
tensile properties – Standard test fluids; sweet and sour service.
Bespoke fluid is an option. – Arrhenius extrapolation of test results to provide
service life at different temperatures
NORSOK M710 – Service life prediction
• Benefits: – Very good comparison tool for evaluating different material choices – Provides indications of service life at temperature based on
extrapolation – Long test times provide understanding of degradation behavior in
material • Challenges:
– Method not suitable if deterioration is not linear – Unsuitable if no deterioration occurs, or if reaction is abrupt – Comparison tool only, not suited to give absolute application driven
parameters – Pure material test, not application specific – Uncertainty in accuracy of extrapolation
• Methodology: – Test jig with O-rings exposed to a standard gas
mixture – Temperature either 100°, 150° or 200°C – most
testing done at 100°C – Pressure set at 150 bar – 10 decompressions – Evaluation of O-rings after decompressions
NORSOK M710 – Rapid Gas Decompression
• Benefits: – Easy comparison between materials – Good method for understanding level of resistance to
RGD in individual materials • Challenges:
– Testing done on unsupported O-rings – Supported seals with good design may function
despite failure in RGD test – Not directly translatable to real applications – Testing done at lower temperatures and pressures
than normally seen in applications
NORSOK M710 – Rapid Gas Decompression
ISO 23936 – production fluid seals
• Part 1 thermoplastics – will not be covered as this is not typically used in the industry. Not a good standard.
• Part 2 elastomers – based on NORSOK M710. This standard will most likely replace NORSOK M710 for elastomer requirements.
ISO 23936 – 2
• Same scope and methodology as in NORSOK M710 – elastomers only
• Also covers hoses, flex joints, downhole packers, bridgeplugs and BOP seals – Materials testing is same as for production seals
• Provides methodology for qualification of materials and manufacturers
• QC requirements • Material standard only, no functional
requirements or testing
ISO 10423 / API 6A – WH, XMT, WO
• Scope: functional requirements for wellhead (WH), Xmas tree (XMT) and workover (WO) equipment
• Annex F provides functional test requirements for non-metallic seals
• QC requirements
ISO 10423 Annex F1.11 (PR2 test) • Methodology:
– Cyclic temperature and pressure testing of sealing system using actual seal and gland
– Temperatures: TMin, TRoom, TMax
– Pressures: PNom, PMax
– Test medium: water / water based fluid or Nitrogen gas
– Hold points: 1 hr – Acceptance criteria: pressure
drop
ISO 10423 Annex F1.11 • Benefits:
– Functional test of actual sealing system – Gas medium provides applicable testing for
gas sealing systems – Sealing at both low and high temperatures is
a challenge, and thus design is verified to full range of application
• Challenges: – Acceptance criteria of pressure drop too
lenient for gas applications: should use «zero bubbles»
– Pressure releases may occur too rapidly and cause inadvertent RGD effects – needs to be controlled
ISO 10423 Annex F1.13
• Methodology: – Immersion test using actual seal and groove – Test fluid is sweet or sour service – Temperature and pressure is max for application – Duration is 160 hrs – Post exposure pressure testing at high and low
temperature with sealing as acceptance criteria
ISO 10423 Annex F1.13 • Benefits:
– Methodology combines functional testing and exposure testing – Acceptance criteria of no leakage proves functionality after exposure
to production fluid • Challenges:
– Exposure duration too short for any real measure of long term effects – Does not cover RGD effects
ISO 13533 – BOPs • Scope: functional testing of
BOPs, both RAM type and annular type
• Material requirements not covered, should use ISO 23936
• Testing covers both sealing function, shear function and temperature/pressure cycling
ISO 14310 – Packers and bridge plugs
• Scope: Functional standard covering packers and bridge plugs for down-hole applications
• Several levels of validation testing – V5 to V0, where V0 is the most stringent level.
• V0 requires gas sealing tests at temperature and pressure with zero bubbles as acceptance criteria.
• Requirement for manufacturers are included in standard
ISO 13628-6 – hydraulic fluids • Scope: functional and
material testing of hydraulic fluid – may also be used for polymer/elastomer materials
• Annex C covers qualification of hydraulic fluid
• Standard not specifically written for qualification and testing of materials
Different NBR’s exposed to control fluid
ISO 13628-6 • Methodology:
– Immersion type testing of materials in hydraulic fluid
– Temperature: 70°C and TMax
– No pressure required – Duration up to 3 months with
intermediate durations at 1 week and 1 month
– Post exposure testing do not include tensile testing
ISO 13628-6 • Benefits:
– Generic test for all types of materials in hydraulic fluids – Easy to compare different materials – Long test duration
• Challenges: – Lack of mechanical testing of materials required – Only two temperatures makes it impossible to perform
Arrhenius extrapolations – No functional testing of sealing systems required
Soft Seal Qualification Guideline
• Guideline that describes scope for relevant subsea soft seal industry standards – what it DOES test for and what it DOESN’T test for ….
• Gives both benefits and challenges with each standard
• Provides tips on how to best use each standard
Qualification summary • Standards offer a set of rules and regulations for soft seal
qualification – however it is always «fit for service» that is ultimate goal
• Many applications not well covered by standards • Many service environments outside standard
temperatures, pressures and chemistry covered by standards
• Use standards as guide to qualification testing, NOT as the Bible – the application must always come before industry requirements
Concluding remarks
• Industry standards are perhaps a blessing AND a curse
• Fit for purpose is the ultimate qualification criteria
• Standards and guidelines are minimum requirements, and should be combined with knowledge, experience and specific needs
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