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ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE

Problem Definition

  • During the operation of a petrochemical plant (located in Middle East), recurring appearance of cracks in dissimilar metal welding joint of a critic, high-pressure steam pipe has been detected (2010-2014).
  • Cracks appear periodically over the same area, which is the butt weld joining two pieces made of different materials A-335-P91 and SS347H. Weld material is INCONEL625.
  • 24” diameter and great thickness due to severe operating conditions: tª=530ºc, p=110 bar
  • None of the reparations conducted so far has been effective to stop recurring breakage after 6-12 months.
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE

Fig. 1: 24″ High pressures steam line actual disposition and welidng features

ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
Fig. 2: Failures sequence

Methodology

ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE

Design and Fabrication Data:

  • Welding detail
  • Welding process
  • Pre and Post welding thermal treatments
  • Materials (properties, storage…)
  • Inspections and NDT

Operation Data

  • Previous observations and Evidences
  • Failures record and details (critical area pictures, crack pictures…)
  • Macrographs, metallography, hardness tests, traction tests, chemical composition.

Regular Operation

  • Pipe and welding on operation conditions
  • Welding process
  • Residual stresses

Best Mechanical and Process Engineering Practices

  • Simulation: FEA
  • International Codes (ASME, FFS)
  • Physical Modelling (understanding how it works)
  • Tests and Hypothesis Modelling
  • Corrective Measures Modelling

2.1: DETAIL LEVEL 1

  • Piping and welding analysis under operation conditions

2.2: DETAIL LEVEL 2

  • Welding process simulation

2.3. DETAIL LEVEL 3

  • Tests to obtaining residual stresses

Observations and Evidence

  • Laboratory Tests

Analysis and determination of Failure Cause

  • Specific proposal of corrective measures
  • Modification of welding detail + Pipe spool
  • PWH
  • Modification of welding process and pass sequences
  • Modification of welding filler material

1. Problem Awareness

ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE

2. Physical characterization

2.1 Detail Level 1- Pipe & Weld Analysis under Operation Conditions

ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE

2.2 Detail Level 2- Welding process simulation

ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE
ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE

2.3 Failure Causes

ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE

3. Solution. Corrective Measures

3.1 Installation of Spool Pipe section between P91 and SS347H

ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE

3.2 Definition of new PWHT

ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE

3.3 Modification of welding pass sequence

ROOT CAUSE ANALYSIS AND CORRECTIVE MEASURES OF DISSIMILAR WELD JOINT FAILURE IN A HIGH PRESSURE STEAM PIPE

ABOUT THE PROJECT

  • Solution proposed has solved a critical and recurring problem which involved a high cost in terms of plant availability.

  • Project execution was subjected to hard constraints of time, and had to be solved over a 2-months period (remaining time until Turnaround).

  • Solid and consistent methodology thanks to simulation.