Sour Service Testing of Girth
Welds
Dr Chris Fowler FIMMM
Global Director Bodycote Corrosion

The Four Point Bend Test
History
ASTM G39
ISO 7539-2
Homogeneous Prismatic Samples
Loaded by Deflection
Elastic Region only.
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The 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 Test
History
EFC 17
Implies root intact sample
Provides Strain Gauge Formulae.
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The 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 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 Test
Reality
Weld Root intact
NON Homogenous
Curved
With miss-match
Thickness (FEA)
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The Four Point Bend Test
Reality
Carbon Steel v CRA’s
Ambient Temperature
High Temperature
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The Four Point Bend Test
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The Four Point Bend Test
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The 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 Test
Loading Issues (2)
Strain Gauge Location
Strain distribution across width and length
Miss-match
Load Stability
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The Four Point Bend Test
Evaluation
No standard practice.
New section in EFC 16
EFC 17-x10 & SEM or Metallography
Not covered by either TM0177 or ISO 15156
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The Four Point Bend Test
Historically
Loaded 72% SMYS
Elastic Region
Now
Used as Weld Qualification
At high % AYS
Possible Plastic Zone
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The 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.
or
THE FULL RING TEST
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The 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 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 Test
Schematic(1)
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The Full Ring Test
Schematic(2)
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The 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 Test
Residual Stress
Residual stress from pipe manufacture
retained
Residual stress from welding retained
Residual 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 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 Test
Monitoring
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The Full Ring Test
Sample Selection
Full Pipe section tested
More material tested
Avoids randomness of selection
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The Full Ring Test
Projects
BP Miller
Mobil Beryl
Bluestream
ADCO – various
Agip
Chevron
Statoil
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The Full Ring Test
Overall Advantages
A realistic test
Simulates the Field Conditions
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The 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 Test
The Real Test
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The Full Ring Test
The Real Test
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The Full Ring Test
Acknowledgements
Conoco Phillips
BP
ADCO
Technip
Bluestream
To name but a few!
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