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Sour Service Testing of Girth Sour Service Testing of Girth WeldsWelds
Dr Chris Fowler FIMMMGlobal Director Bodycote Corrosion
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The Four Point Bend TestThe Four Point Bend Test
History
ASTM G39ISO 7539-2
Homogeneous Prismatic SamplesLoaded by DeflectionElastic Region only.
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The Four Point Bend TestThe Four Point Bend Test
History
EFC 16 (Carbon Steels)
Shows weld root intact sample.Longitudinal and Transverse.
Mentions Strain Gauging
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The Four Point Bend TestThe Four Point Bend Test
History
EFC 17Implies root intact sample
Provides Strain Gauge Formulae.
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The Four Point Bend TestThe Four Point Bend Test
NACE TM0177(Carbon Steels & CRA’s)
Mentions Four Point Bends as an supplementary test.
WG085f Tasked with writing a test procedure.
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The Four Point Bend TestThe Four Point Bend Test
NACE MR0175 / ISO 15156(Carbon Steels & CRA’s)
4PB test method included for carbon steels (80 / 90% AYS) and CRA’s (100% AYS)Evaluation of carbon steels for SSC not well defined (refers to NACE TM0177!)Evaluation method for 4PB carbon steels detailed for SOHIC and SZC and NOT SSC.Evaluation of CRA’s for SSC and SCC not well defined (refers to NACE TM0177 and EFC 17).
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The Four Point Bend TestThe Four Point Bend Test
Reality
Weld Root intact NON Homogenous
CurvedWith miss-matchThickness (FEA)
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The Four Point Bend TestThe Four Point Bend Test
Reality
Carbon Steel v CRA’sAmbient Temperature
High Temperature
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The Four Point Bend TestThe Four Point Bend Test
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The Four Point Bend TestThe Four Point Bend Test
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The Four Point Bend TestThe Four Point Bend Test
Loading Issues (1)80% & 90% AYS!!!
Compensates for loss of Residuals?NOT ALL IN THE SAME DIRECTION
What is the AYS?Tensile data or Flexural 4pt bend?
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The Four Point Bend TestThe Four Point Bend Test
Loading Issues (2)
Strain Gauge LocationStrain distribution across width and length
Miss-match Load Stability
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The Four Point Bend TestThe Four Point Bend Test
Evaluation
No standard practice.New section in EFC 16
EFC 17-x10 & SEM or MetallographyNot covered by either TM0177 or ISO 15156
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The Four Point Bend TestThe Four Point Bend Test
Historically Loaded 72% SMYS
Elastic RegionNow
Used as Weld QualificationAt high % AYS
Possible Plastic Zone
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The Four Point Bend TestThe Four Point Bend Test
The Way Forward
Scrap the Test!Recognise the Test limitations
Write a comprehensive test procedure.New workgroup under EFC charged with
producing a procedure.Review LOADING LEVELS.
orTHE FULL RING TEST
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The Full Ring TestThe Full Ring Test
Published by the UK Health & Safety Executive as
OTI 95-635
Included in ISO15156/NACE MR0175 as an option
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The Full Ring TestThe Full Ring Test
Description
A Test method which simulates worst case conditions but with a touch or reality
A method which qualifies linepipe material and associated welds for use in Sour Service.
Verified against Full Scale Pressure Tests.
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The Full Ring TestThe Full Ring Test
Schematic(1)
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The Full Ring TestThe Full Ring Test
Schematic(2)
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The Full Ring TestThe Full Ring Test
Load Considerations
Pipe loaded to the level of maximum DESIGN
Loaded in the direction of the field applied stress.
Edge effects avoided.Variation in AYS not important
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The Full Ring TestThe Full Ring Test
Residual Stress
Residual stress from pipe manufacture retained
Residual stress from welding retainedResidual stress from repairs retained
Residual strain from pipe bending retained
No guess at the compensation for loss of residual stress required.
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The Full Ring TestThe Full Ring Test
Weld Repairs
Root repair can be included
Full thickness repair can be included.
Can be conducted at elevated temperature.
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The Full Ring TestThe Full Ring Test
Monitoring
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The Full Ring TestThe Full Ring Test
Sample Selection
Full Pipe section tested
More material tested
Avoids randomness of selection
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The Full Ring TestThe Full Ring Test
Projects
BP MillerMobil BerylBluestream
ADCO – variousAgip
ChevronStatoil
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The Full Ring TestThe Full Ring Test
Overall Advantages
A realistic test
Simulates the Field Conditions
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The Full Ring TestThe Full Ring Test
Conclusions
•NO loss of residual stress/strain•Applied load in the correct direction
•NO sample selection problems•Girth weld and repair can be included.
•Genuine surface exposed to the environment.•Controlled loading
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The Full Ring TestThe Full Ring Test
The Real Test
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The Full Ring TestThe Full Ring Test
The Real Test
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The Full Ring TestThe Full Ring Test
AcknowledgementsConoco Phillips
BPADCO
TechnipBluestream
To name but a few!
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