Aspect Before Analysis

11 cases · 27 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

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Aspect before cleaning of the heavy U bolt pipe clamp, 38 mm diameter wire, at the fractured position. It is possible to see that it broke in a region where the clamp was no longer coated and there is no insert in the groove (at the internal clamp diameter). The fracture is transverse to the clamp axis.
522
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - General View
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
The four bolts have fractured in the same position, close to the end, and the corrosion marks in the thread suggest that they have been tightened only a few fillets in a tapped hole. This condition could be responsible for overloading the fillets, relaxing the applied bolt preload, and intensifying cyclic stresses.
192
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - General View
Detailed aspect of the eye bolt fracture position, with strong plastic deformation indicating ductile overloading. The red marks in the thread surface of the bolt (in the left side of the image) correspond to the position where the nut was tight. Thread fillets adjacent to the fracture presented secondary cracks.
1125
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Aspect Before AnalysisDf - Ductile Fracture
Aspect of the bolt analyzed to qualify the lot of fasteners to be adopted in subsea conditions, exposed to cathodic protection.
62
VIEW
ML00106 / Dec.2017
Inconel 718 Submarine Bolt
M - NiCrFe AlloyP - BoltAp - SubseaCd - Typical manufacturing
Cm - Aspect Before AnalysisDf - General View
Aspect of the bolt with a special head, to be adopted in subsea condition. M12, 1/2" 13UNC.
342
VIEW
ML00105 / Jun.2018
Inconel 718 Bolt of Special Head
M - NiCrFe AlloyP - FastenerAp - SubseaCd - Typical manufacturing
Cm - Aspect Before AnalysisDf - General View
Aspect of the bolts M12 x 25.
41
VIEW
ML00101 / Nov.2017
High Strength 316SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Aspect Before AnalysisDf - General View
Socket head capscrew bolt, M10 x 70, 1.5 coarse thread.
63
VIEW
ML00087 / Nov.2017
High Strength Austenitic SS Bolt
M - Austenitic Stainless SteelP - BoltAp - SubseaCd - Typical manufacturing
Cm - Aspect Before AnalysisDf - General View

More from these cases

ML00171 — Corrosion Fatigue of U Bolt Pipe ClampM - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Aspect of the U bolt clamp with partial detachment of the coating (white brown) in a region where the polimeric insert (dirty white) is still in the wire groove at the internal clamp diameter (ID).
91
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - General View
Detailed aspect of the fractured position, in a region where the clamp was no longer coated and there is no insert in the groove (at the internal clamp diameter). The fracture is transverse to the clamp axis.
86
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Fracture
Same aspect of the previous image after cleaning, showing a subcritical propagation aspect (fatigue), starting at the groove (ID) and also at the clamp surface in the OD.
75
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Fracture
In the region where the polimeric insert was loose, the protective coating of the clamp has suffered detachment.
69
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Layer Detachment
Close to the ID of the clamp, at the groove position, there are cracks in the coating (white brown) and also at the substrate.
63
VIEW
ML00171 / Feb.2021
Corrosion Fatigue of U Bolt Pipe Clamp
M - Low Carbon SteelP - BoltAp - ShipCd - Corrosion Fatigue
Cm - Aspect Before AnalysisDf - Cracks

+3 more from this case →

ML00157 — Bolts Under Chloride SCC ConditionsM - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Aspect of a broken 5/16" bolt that was operating inside the pressure vessel in a condition that exceeds the limits of use of the AISI 316 steel. The fracture is located close to the position where there was the bolt head and the threads were "removed" close to the fracture surface.
75
VIEW
ML00157 / Feb.2020
Bolts Under Chloride SCC Conditions
M - Austenitic Stainless SteelP - BoltAp - Oil and GasCd - Stress Corrosion
Cm - Aspect Before AnalysisDf - Fracture
ML00130 — Fatigue Fracture of Overloaded BoltsM - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
The corrosion marks in the thread surface indicate that the bolt was not properly tightened in the tapped hole. The length of thread engagement should be at least 1x of the bolt diameter, in this case 3/8".
170
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - General View
Macroscopic aspect of the bolt fracture. Part of it is flat from the bottom of the thread.
166
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - Fracture
The head of the bolts presented the marks that indicated they were manufactured to meet ASTM A449 type 1 bolt, that is a medium strength low alloy steel, quenched and tempered.
148
VIEW
ML00130 / Jun.2018
Fatigue Fracture of Overloaded Bolts
M - Low Alloy Medium Carbon QTP - FastenerAp - O&G Well DrillingCd - Mechanical Fatigue
Cm - Aspect Before AnalysisDf - At the Surface
ML00120 — Ductile Rupture of a Carbon Steel Eye BoltM - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Apect of the 1/2" ND bumper eye bolt that was fractured (in the left side of the figure) in the position where the nut was tight.
192
VIEW
ML00120 / Jun.2018
Ductile Rupture of a Carbon Steel Eye Bolt
M - Low Carbon SteelP - FastenerAp - AutomotiveCd - Overload
Cm - Aspect Before AnalysisDf - General View