Subsea

7 cases · 11 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

Capture method: Kalling Etched Macro clear all

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Macrography of the longidutinal section of a non broken allen bolt, at the threaded body to bolt head transition. The granular structure is different through the bolt, with refined structure in the threaded body and coarse at the transition.
44
VIEW
ML00139 / Jun.2018
Hydrogen Fracture of a 17-4 PH Allen Bolt
M - Precipitation Hardened Stainless SteelP - Allen BoltAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched MacroDf - Longitudinal Section
17-4 PH rod, tubular, OD 10.6mm, wall thickness about 3.5 mm. Macrography of the rod in a transverse section showing the pitting in a position where it is almost through wall.
86
VIEW
ML00121 / Feb.2018
Pitting Corrosion in a Subsea System
M - Austenitic / MartensiticP - Rod & CylinderAp - SubseaCd - Pitting Corrosion
Cm - Kalling Etched MacroDf - Pitting
Macrography of a longitudinal section of the fitting to tubing weld, with the longitudinal cracking at the tubular fitting position.
69
VIEW
ML00094 / Sep.2017
MIC of a Subsea Hydraulic Line
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Behavior
Cm - Kalling Etched MacroDf - Longitudinal Section
The macrography shows the longitudinal section of the allen bolt, 1/2" nominal diameter, that was machined from a heat treated bar (solution annealed and aged). The granular structure presents differences in the grain sizes. At the bolt head (external surface of the original bar) the austenitic grain size is larger than in the center of the bar where the particles in segregated bands "arrested" the grains during hot forming and solution annealing.
58
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched MacroDf - Machined Thread
Macrography of a longitudinal section of the broken bolt, at the fracture position, showing that the fracture is partially flat (left side), where the macroscopically aspect is brittle, and a final ductile fracture (right side). Interesting to note that there is a large longitudinal crack, secondary (transverse to the fracture surface).
143
VIEW
ML00074 / Jun.2018
Hydrogen Cracking of a 17-4 PH Subsea Bolt
M - Precipitation Hardened Stainless SteelP - FastenerAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched MacroDf - Longitudinal Section
Macrography of the welded joint upper part. Transverse section showing the different zones studied in this ML. See the schematic drawing in the next image.
454
VIEW
ML00045 / Aug.2017
Subsea Tubular F6NM Martensitic SS
M - Martensitic Stainless SteelP - Fabrication WeldAp - OffshoreCd - Welding
Cm - Kalling Etched MacroDf - Welded Joint
Micrographic detail of a longitudinal section of the connector, at the fracture surface (in the top), showing intergranular secondary cracks. There is a large amount of delta phase precipitated intergranular and intragranluar.
49
VIEW
ML00078 / Jun.2017
Hydrogen Cracking of IN 718 Subsea Connector
M - NiCrFe AlloyP - ForgingAp - SubseaCd - Hydrogen Embrittlement
Cm - Kalling Etched MacroDf - Intergranular Cracking

More from these cases

ML00094 — MIC of a Subsea Hydraulic LineM - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Behavior
Macrography of the fitting to tubing welded joint. The internal surface of the fitting (left side) is rough compared to the internal surface of the tubing (right side). The cracking is located only in the fitting and presented no association with the welded joint.
41
VIEW
ML00094 / Sep.2017
MIC of a Subsea Hydraulic Line
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Behavior
Cm - Kalling Etched MacroDf - Longitudinal Section
ML00089 — Inconel 718 Allen Bolt for Subsea ApplicationM - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Micrographic detail of a longitudinal section of the bolt, in the center of the thickness (ND 1/2"). Although the material was hardened by heat treatment (solution annealing and aging), the microstructure observed by optical microscopy does not reveal the intragranular precipitation.
33
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched MacroDf - Austenite
The micrography of a longitudinal section, at the bolt head close to the surface of the original bar. In this region the material increased the grain size due to the lack of particles (inclusions), to "arrest" the grain boundaries (during hot forming and solution annealing). The smaller grain size is located in the center of the bar, that concentrated the inclusions.
30
VIEW
ML00089 / Sep.2017
Inconel 718 Allen Bolt for Subsea Application
M - NiCrFe AlloyP - Machined PartAp - SubseaCd - Typical manufacturing
Cm - Kalling Etched MacroDf - Dual grain sizes
ML00045 — Subsea Tubular F6NM Martensitic SSM - Martensitic Stainless SteelP - Fabrication WeldAp - OffshoreCd - Welding
Macrography of the welded joint, at the root position, presenting the different zones studied in this ML. Transverse section. See the schematic drawing in the next image.
47
VIEW
ML00045 / Aug.2017
Subsea Tubular F6NM Martensitic SS
M - Martensitic Stainless SteelP - Fabrication WeldAp - OffshoreCd - Welding
Cm - Kalling Etched MacroDf - Welded Joint