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ML00049 - Apr.2017donated by: David Hadjadj

Pipe to Flange Welded Joint in a 14" ND Superduplex Spool

Macrography of the flange HAZ. The macroscopic aspect shows a remarkable modified region.

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of the . The macroscopic aspect shows a remarkable modified region.
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Material

Super Duplex Stainless Steel
  • UNS S32750
  • NF EN 10217-7 X2CrNiMoN25-7-4
  • NF EN 10222-5 X2CrNiMoN25-7-4
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Description

The to welded part was due to the , and of the line. The problem was associated to the flange material (a fabrication problem) that presented preferential dissolution and . The procedure adopted a bad practice of remelting the last bead, probably to create a good finishing condition.

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Chemistry (% in weight)

Pipe Product Analysis

0.042C; 0.37Si; 0.84Mn; 0.005P; 0.002S; 25.12Cr; 7.20Ni; 3.52Mo; 0.017Nb; 0.21Cu; 0.05W.

Flange Product Analysis

0.078C; 0.72Si; 1.34Mn; 0.027P; 0.012S; 22.97Cr; 7.64Ni; 2.86Mo; 0.020Nb; 0.16Cu; 0.19W.

Weld Metal Analysis

0.048C; 0.36Si; 0.85Mn; 0.023P; 0.006S; 24.64Cr; 8.80Ni; 3.21Mo; 0.019Nb; 0.11Cu; 0.38W.

Associated Images
Macrography of the pipe to flange weld. Transverse section identifying the regions of the base materials, heat affected zones and weld metal, which microstructures are presented in this ML.
527
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MacroDf - Welded Joint
Macrography of the pipe heat affected zone.
55
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MacroDf - Heat Affected Zone
Macrography of the flange HAZ. The macroscopic aspect shows a remarkable modified region.
56
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MacroDf - Heat Affected Zone
Micrography of the pipe base metal presenting a refined duplex ferritic austenitc structure, banded.
47
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Duplex structure
Micrographic detail of the pipe base metal presenting a refined duplex ferritic austenitc structure, banded.
55
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Base Metal
Micrographic detail of the pipe base metal presenting a refined duplex ferritic austenitc structure, banded.
56
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Duplex structure
Micrography of the flange base metal presenting a coarse duplex ferritic austenitc structure.
88
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Duplex structure
Micrographic detail of the flange base metal presenting a coarse duplex ferritic austenitc structure. Detrimental phases associated to the ferritic structure.
62
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Duplex structure
Micrographic detail of the flange base metal presenting a coarse duplex ferritic austenitc structure and detrimental phases associated to the ferritic structure.
47
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - Electrolytic Etch Micrography by SEMDf - Duplex structure
Micrographic detail of the flange base metal presenting a coarse duplex ferritic austenitc structure and detrimental phases associated to the ferritic structure.
39
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - Electrolytic Etch Micrography by SEMDf - Duplex structure
Micrography of the pipe heat affected zone. In the left the pipe base metal, with banded duplex structure; and in the right the weld metal, with Widmanstatten morphology of the structure.
43
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Heat Affected Zone
Higher magnification of the pipe heat affected zone. The amount of ferrite increases with the proximity of the fusion line (to the right).
38
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Heat Affected Zone
Micrography of the fusion line of the weld in the pipe side.
44
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Fusion Line
Micrography of the flange heat affected zone. In the right the flange base metal, with coarse structure and detrimental phases associated to the ferrite; and in the left the weld metal, with Widmanstatten morphology of the structure.
36
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Heat Affected Zone
Higher magnification of the flange heat affected zone. The detrimental phases in the ferrite structure is clearly being dissolved with the proximity of the fusion line (to the left).
28
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Heat Affected Zone
Micrography of the fusion line of the weld in the flange side.
36
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Fusion Line
Micrography of the root weld metal. Duplex ferritic austenitic structure with Widmanstatten morphology.
30
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Weld Metal in the Root
Micrographic detail of the root weld metal. Duplex ferritic austenitic structure with Widmanstatten morphology.
30
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Weld Metal in the Root
Micrography of the center of the weld metal (fill pass). Duplex ferritic austenitic structure.
24
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Weld Metal in the Center
Micrographic detail of the center of the weld metal (fill pass). Duplex ferritic austenitic structure.
27
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MacroDf - Weld Metal in the Center
Micrography of the weld metal (cap) at the surface. It is clear that the last bead of the weld was remelted in an autogenous condition, probably to create a better finish, since the layer is less than 2 mm deep. This is a typical bad practice since a large amount of ferrite is retained by the quick cooling.
31
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Weld Metal in the Cap
Micrographic detail of the weld metal (cap) at the surface. A large amount of ferrite is retained by the quick cooling at the surface.
24
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Weld Metal in the Cap
Micrographic detail of the flange base metal presenting a coarse duplex ferritic austenitc structure.
34
VIEW
ML00049 / Apr.2017
Pipe to Flange Welded Joint in a 14" ND Superduplex Spool
M - Super Duplex Stainless SteelP - Piping spoolAp - Oil and GasCd - Removed From Service
Cm - NaOH Electrolytic Etched MicroDf - Base Metal