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ML00068 - Sep.2020

Corrosion Fatigue of a 5" Drill Pipe

Aspect of the washout in the 5" drill pipe, in the pipe body, before cleaning the surface.

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Aspect of the in the 5" , in the body, before cleaning the surface.
M

Material

Low Alloy Medium Carbon QT
  • API 5D S135
Ds

Description

The , that consists of a welded to two tool joints ( and box), suffered in the body. The region of washout presented parallel tool marks at the of the pipe, with multiple propagating by a - mechanism.

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Chemistry (% in weight)

Pipe Analysis

0.25C; 0.32Si; 0.85Mn; 0.011P; 0.007S; 1.32Cr; 0.07Ni; 0.78Mo.

Associated Images
Aspect of the washout in the 5" drill pipe, in the pipe body, before cleaning the surface.
683
VIEW
ML00068 / Sep.2020
Corrosion Fatigue of a 5" Drill Pipe
M - Low Alloy Medium Carbon QTP - Seamless PipeAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - At the Surface
Aspect of the washout in the 5" drill pipe, in the pipe body, after cleaning the surface. The surface presents several parallel tool marks that are not typical in the pipe since the torque is applied in the tool joint.
195
VIEW
ML00068 / Sep.2020
Corrosion Fatigue of a 5" Drill Pipe
M - Low Alloy Medium Carbon QTP - Seamless PipeAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Surface AspectDf - At the Surface
The longitudinal section of the 1/2" thick pipe close to the washout position shows that the external tool marks are like notches that are corroded and cracks are iniciating from the corroded regions. The top of the figure presents the external pipe surface and the bottom of the figure presents the internal pipe surface, with a green coating and the rusted washout.
154
VIEW
ML00068 / Sep.2020
Corrosion Fatigue of a 5" Drill Pipe
M - Low Alloy Medium Carbon QTP - Seamless PipeAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - NItal Etched MacroDf - Longitudinal Section
Macrography of the longitudinal section of the pipe presenting multiple cracks from the tool marks.
122
VIEW
ML00068 / Sep.2020
Corrosion Fatigue of a 5" Drill Pipe
M - Low Alloy Medium Carbon QTP - Seamless PipeAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - NItal Etched MacroDf - Cracks Transverse to the Surface
The microstructure of the pipe, presented in a longitudinal section, is an uniform tempered martensite.
105
VIEW
ML00068 / Sep.2020
Corrosion Fatigue of a 5" Drill Pipe
M - Low Alloy Medium Carbon QTP - Seamless PipeAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Martensite
The micrography in the as polished condition of the longitudinal section of the pipe close to the washout, shows that at the tool mark tip (notch from the external surface) a fatigue crack already started from a corroded region (pitting).
187
VIEW
ML00068 / Sep.2020
Corrosion Fatigue of a 5" Drill Pipe
M - Low Alloy Medium Carbon QTP - Seamless PipeAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Micrography by OMDf - Pitting
Micrographic detail, in the as polished condition, of the corrosion fatigue crack.
89
VIEW
ML00068 / Sep.2020
Corrosion Fatigue of a 5" Drill Pipe
M - Low Alloy Medium Carbon QTP - Seamless PipeAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Micrography by OMDf - Fatigue Crack
The micrography of one of the (multiple) cracks shows the slightly irregular morphology of the cracking, typical of a corrosion-fatigue mechanism.
281
VIEW
ML00068 / Sep.2020
Corrosion Fatigue of a 5" Drill Pipe
M - Low Alloy Medium Carbon QTP - Seamless PipeAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Corrosion Cracking
Micrographic detail of the slightly irregular crack propagation, typical of a corrosion-fatigue mechanism.
76
VIEW
ML00068 / Sep.2020
Corrosion Fatigue of a 5" Drill Pipe
M - Low Alloy Medium Carbon QTP - Seamless PipeAp - O&G Well DrillingCd - Corrosion Fatigue
Cm - Nital Etched Micrography by OMDf - Corrosion Cracking