Austenitic Stainless Steel

3 cases · 15 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Application: Oil and Gas Detail focus: Sampling and Analysis clear all

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Aspect of a 5/16" bolt manufactured in an AISI 316 austenitic stainless steel, that was also operating inside the pressure vessel, but was not yet damaged. It is a hexagonal head bolt, 1 1/2" long, fastened with a hexagonal nut and a lock washer.
118
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Aspect Before AnalysisDf - General View
Flanged case, 640mm long. The photo presents a general view of the instrumentation system, destroyed after only 6 months in subsea service. The system was manufactured using only 316 stainless steel and the case was 20 mm thick.
336
VIEW
ML00122 / Feb.2018
Crevice Corrosion in a Subsea System
M - Austenitic Stainless SteelP - CaseAp - Oil and GasCd - Crevice
Cm - Aspect Before AnalysisDf - General View
Draft of the completion riser after removal of the external case showing the hydraulic line position where the 316 tubing is welded by orbital autogenous GTAW to the Nitronic fitting (stab). In the design of these hydraulic lines, the position of the cracking in the fitting is associated to a slightly bent condition of the fitting due to the misaligment of the tubing axis and the stab axis in the connector, visible in the draft.
1082
VIEW
ML00095 / Sep.2017
MIC of a Riser Control Line
M - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Cm - Identification drawingDf - General View

More from these cases

ML00157 — Bolts Under Chloride SCC ConditionsM - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Low magnification microscope image showing the aspect of the thread close to the fracture surface. Looks like a wear or strong corrosion, but in fact the threads were removed because they were cracked, as can be seen in the next figures.
67
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Surface AspectDf - Low Mag
Macrography of the longitudinal section of a fractured bolt, still threaded to the nut and with the lock washer. The cracks can be seen in several positions: in the threads (removing then); in the center of the bolt (branched) and also in the washer (longitudinal branched cracks).
65
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Macro Oxalic Acid Electrolytic EtchedDf - Longitudinal Section
ML00122 — Crevice Corrosion in a Subsea SystemM - Austenitic Stainless SteelP - CaseAp - Oil and GasCd - Crevice
Aspect of the instrument system after disassembling. The internal part of the case, where the electronic device was operating, was wet by seawater and failed to send signals to the surface.
258
VIEW
ML00122 / Feb.2018
Crevice Corrosion in a Subsea System
M - Austenitic Stainless SteelP - CaseAp - Oil and GasCd - Crevice
Cm - Aspect Before AnalysisDf - General View
Microstructure of the welded region of the padeye, at the fusion line. The weld metal is dendritic, austeno ferritic, in the left side of the figure. The heat affected zone is in the center of the figure and shows no changes in relation to the base metal. The padeye base metal is to the right side of the figure.
120
VIEW
ML00122 / Feb.2018
Crevice Corrosion in a Subsea System
M - Austenitic Stainless SteelP - CaseAp - Oil and GasCd - Crevice
Cm - Micrography by OM using A262 Method ADf - Welded Joint
Micrographic detail of the fusion line of the welded joint of the padeye. The connector where the padeye was installed was welded to the case, but presented no evidences of corrosion.
110
VIEW
ML00122 / Feb.2018
Crevice Corrosion in a Subsea System
M - Austenitic Stainless SteelP - CaseAp - Oil and GasCd - Crevice
Cm - Micrography by OM using A262 Method ADf - Welded Joint
ML00095 — MIC of a Riser Control LineM - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Aspect of the hydraulic line samples removed from service to be analyzed. Tubing and welded joint (bottom sample) between the 316 tubing (left side of the sample) and the nitronic fitting (right side of the sample). The cracking is located 10 mm far from the weld, autogenous orbital GTAW.
108
VIEW
ML00095 / Sep.2017
MIC of a Riser Control Line
M - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - General View
Scanning electron microscopy image of the external surface of the line at the cracking position showing multiple cracks, branched, transverse to the line axis.
79
VIEW
ML00095 / Sep.2017
MIC of a Riser Control Line
M - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Cm - Surface Aspect by SEMDf - External Surface
Detail of the welded joint between the 316 tubing (left side) and the nitronic fitting (right side). The through wall cracking is transverse to the line, in the fitting, 10 mm far from the weld, where the fitting was slightly bent to be assembled (cold bent).
65
VIEW
ML00095 / Sep.2017
MIC of a Riser Control Line
M - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Welded Joint
The longitudinal section macrography of the welded joint sample shows that the cracks are positioned in the fitting, about 10 mm far from the weld.
60
VIEW
ML00095 / Sep.2017
MIC of a Riser Control Line
M - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Cm - Macro Oxalic Acid Electrolytic EtchedDf - Longitudinal Section
As polished micrography of the hydraulic line sample in the longitudinal section, close to the outer diameter, showing that the cracks are branched and thin, opened to the external surface.
58
VIEW
ML00095 / Sep.2017
MIC of a Riser Control Line
M - Austenitic Stainless SteelP - Fabrication WeldAp - Oil and GasCd - Brittle Behavior
Cm - Micrography by OMDf - Close to the External Surface

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