Valve Body

3 cases · 76 images

Crevice Corrosion in a Subsea System — Aspect Before Analysis

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General view of the cylindrical valve body, 6 5/8" nominal diameter, showing a transverse straight crack at the external surface.
406
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Aspect Before AnalysisDf - Crack
Aspect of the cracked valve body, after disassembling and removing the internal parts. The valve is part of a lot that was manufactured by forging a cubic 170mm from a forged bar in SDSS UNS S32760, and heat treated (solution annealed) by the forging company. The fabrication using these bodies included the machining, fillet weld two inserts in Alloy 625, machining again, assembling the internals, and pressure test at 15,000 psi. The cracking occurred during test, only for this valve body.
676
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - Aspect Before AnalysisDf - Cracking
The as polished micrographic aspect of the corroded surface shows pitting and several microcracks, probably associated to the biological attack and material embrittlement. Replication technique.
924
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - As polishedDf - Microcracks

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ML00162 — Valve Body Crack Growth from Weld DefectsM - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
The valve body cylindrical diameter is 6 5/8" and the actuator hole in the body is about 2" diameter. The crack is associated to the hole edge, propagating transverse to the body.
71
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Aspect Before AnalysisDf - General View
The figure illustrates the position of the ball and seats, as well as the valve actuator. The crack is located at the edge of the actuator hole, transverse to the cylindrical body.
63
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Aspect Before AnalysisDf - Longitudinal Section
Penetrant test (dye check) image of the cracks at the surface of the actuator hole, viewed from inside of the body after the longitudinal cut. The aspect of the cracks at the hole, close to the internal side of the valve, is not the same as the aspect of the cracks at the external side (a straigth line), suggesting that the original cracks had propagated by fatigue through wall. The penetrant did not stained too much at the cracked area, indicating that the cracks are not too deep in this position, or are not fully opened to the surface.
62
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Aspect by NDTDf - Crack
Magnetic particle test of the same cracks at the edge of the actuator hole, viewed from inside of the body. The cracks appeared more clearly with this test than with the penetrant test, suggesting that the cracks are not fully opened to the surface.
60
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Aspect by NDTDf - Crack
Longitudinal section of the cylindrical body showing two pieces with the cracks, close to the position of the actuator hole. The valve body thickness is 40 mm at the location where the cracks appeared.
53
VIEW
ML00162 / Apr.2020
Valve Body Crack Growth from Weld Defects
M - Low Alloy Medium Carbon QTP - Valve BodyAp - O&G Well DrillingCd - Fatigue Induced by a Defect
Cm - Longitudinal Section AspectDf - Crack

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ML00134 — Brittle Fracture of a Superduplex Valve BodyM - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Detailed aspect of the cracking, straight and presenting a brittle aspect.
122
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - Aspect Before AnalysisDf - Cracking
Detail of the internal bore, showing a brittle crack through the wall.
106
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - Aspect Before AnalysisDf - Cracking
Aspect of a section cut transverse to the center of the body. The crack is brittle, trough wall, and was arrested in the region where the valve body was welded to the insert.
105
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - Transverse Section AspectDf - Cracking
Microstructural analysis of the valve body structure, close to the position where the cracking has occurred. The structure is ferritic austenitic, with a large amount of detrimental phases associated to the ferritic structure, probably sigma phase.
106
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Sigma
Micrographic detail of the valve body structure, close to the position where the cracking has occurred. The structure is ferritic austenitic, with a large amount of detrimental phases associated to the ferritic structure, probably sigma phase.
102
VIEW
ML00134 / Aug.2020
Brittle Fracture of a Superduplex Valve Body
M - Super Duplex Stainless SteelP - Fabrication WeldAp - SubseaCd - Brittle Fracture
Cm - NaOH Electrolytic Etched MicroDf - Sigma

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ML00092 — MIC of a Valve BodyM - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Aspect of the inner side of a valve body, showing regions of localized corrosion and rust, not expected for this stainless steel.
82
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Corrosion
Evidences of a stagnated fluid in the internal surface of the valve body.
61
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Internal Surface
Deep localized corrosion spots, rusted. There are indications that the roughness of the surface influences the localized corrosion location.
61
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Aspect Before AnalysisDf - Localized Corrosion
The macroscopic aspect of the surface after preparation. Grinding and polishing.
50
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Surface AspectDf - Localized Corrosion
The forged valve presented an uniform tempered martensitic structure, surface hardness 246HB. Replication technique.
42
VIEW
ML00092 / Sep.2017
MIC of a Valve Body
M - Martensitic Stainless SteelP - Valve BodyAp - Oil and GasCd - Brittle Behavior
Cm - Kalling etched, OMDf - Martensite

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