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ML00006 - Apr.2017

Vibration Induced Fatigue in 304SS

The main pipe, ND 18", has suffered a pipe through wall cracking at the margin of the 1 1/2" branch socket weld.

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The main , 18", has suffered a at the margin of the 1 1/2" branch socket weld.
M

Material

Austenitic Stainless Steel
  • UNS S30400
  • ASTM A 358 grade 304
  • ASME B36.19
Ds

Description

The 18" condensate return has suffered at the margin of the socket weld, shortly after start uo. The branch connection was welded to the main pipe in a , using a similar . The crack propagated from the margin of the weld through the pipe body. are clear at the surface. Unsupported instruments in small branch connections may present this kind of failure in the beginning of operation.

C

Chemistry (% in weight)

Main Pipe Analysis

0.03C; 0.53Si; 1.30Mn; 0.027P; 0.013S; 18.23Cr; 8.36Ni; 0.02Mo.

Associated Images
The main pipe, ND 18", has suffered a pipe through wall cracking at the margin of the 1 1/2" branch socket weld.
664
VIEW
ML00006 / Apr.2017
Vibration Induced Fatigue in 304SS
M - Austenitic Stainless SteelP - Longitudinal Seam Welded PipeAp - PipingCd - Vibration Induced Fatigue
Cm - Aspect Before AnalysisDf - Crack
The macro section transverse to the welded region, show that the through wall cracking occurred in the pipe base metal, from the margin of the weld.
191
VIEW
ML00006 / Apr.2017
Vibration Induced Fatigue in 304SS
M - Austenitic Stainless SteelP - Longitudinal Seam Welded PipeAp - PipingCd - Vibration Induced Fatigue
Cm - Macro Oxalic Acid Electrolytic EtchedDf - Through Wall Cracking
Macro transverse to the weld showing that the fracture occurred in the main pipe, at the margin of the weld.
163
VIEW
ML00006 / Apr.2017
Vibration Induced Fatigue in 304SS
M - Austenitic Stainless SteelP - Longitudinal Seam Welded PipeAp - PipingCd - Vibration Induced Fatigue
Cm - Macro Oxalic Acid Electrolytic EtchedDf - Fracture
The fracture surface of the main pipe is presented in low magnification (external pipe surface in the top) showing a flat propagation starting from the contour of the weld margin.
173
VIEW
ML00006 / Apr.2017
Vibration Induced Fatigue in 304SS
M - Austenitic Stainless SteelP - Longitudinal Seam Welded PipeAp - PipingCd - Vibration Induced Fatigue
Cm - Fractography by SEMDf - Margin of the Weld Crack
Fracture surface micromechanism by striation, evidence of FATIGUE.
158
VIEW
ML00006 / Apr.2017
Vibration Induced Fatigue in 304SS
M - Austenitic Stainless SteelP - Longitudinal Seam Welded PipeAp - PipingCd - Vibration Induced Fatigue
Cm - Fractography by SEMDf - Fatigue Striation
Fracture surface micromechanism by striation, evidence of FATIGUE.
147
VIEW
ML00006 / Apr.2017
Vibration Induced Fatigue in 304SS
M - Austenitic Stainless SteelP - Longitudinal Seam Welded PipeAp - PipingCd - Vibration Induced Fatigue
Cm - Fractography by SEMDf - Fatigue Striation
Longitudinal section of the main pipe showing as austenitic structure with small amount of delta ferrite, aligned. The white band in the center of the figure is a segregation band that was not fully etched.
133
VIEW
ML00006 / Apr.2017
Vibration Induced Fatigue in 304SS
M - Austenitic Stainless SteelP - Longitudinal Seam Welded PipeAp - PipingCd - Vibration Induced Fatigue
Cm - Micrography by OM using A262 Method ADf - Austenite
Longitudinal section of the main pipe showing as austenitic structure with small amount of delta ferrite, aligned (black dots).
116
VIEW
ML00006 / Apr.2017
Vibration Induced Fatigue in 304SS
M - Austenitic Stainless SteelP - Longitudinal Seam Welded PipeAp - PipingCd - Vibration Induced Fatigue
Cm - Micrography by OM using A262 Method ADf - Austenite
Micrography transverse to the weld and to the fracture surface (right side of the figure).
116
VIEW
ML00006 / Apr.2017
Vibration Induced Fatigue in 304SS
M - Austenitic Stainless SteelP - Longitudinal Seam Welded PipeAp - PipingCd - Vibration Induced Fatigue
Cm - Micrography by OM using A262 Method ADf - Fracture
Micrography of the section transverse to the weld and in a region close to the fracture surface (to the right side of the figure). The secondary fatigue microcracks are associated to the stress concentration raisers of the margin of the weld, irregular.
110
VIEW
ML00006 / Apr.2017
Vibration Induced Fatigue in 304SS
M - Austenitic Stainless SteelP - Longitudinal Seam Welded PipeAp - PipingCd - Vibration Induced Fatigue
Cm - Micrography by OM using A262 Method ADf - Fatigue Crack