Stress Corrosion Cracking Direct Assessment (SCCDA)

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3. Direct Examination

The purpose of the Direct Examination step is twofold. First, this step will either validate or nullify the decision criteria for SCC direct examination site selection. Second, this step provides for the actual digging of the suspected SCC locations for inspection. When performed, these dig sites will render the severity, extent, and type of SCC (intergranular or transgranular cracking). This information is crucial in the post assessment process in order to develop a predictive model and allow for modifications. A wide range of related physical data is collected, along with Magnetic Particle Inspection (MPI) of the susceptible area. NACE Standard RP0204-2004 outlines four different MPI techniques for inspecting the external surface of pipelines. They are:

• DPMI- Dry Powder MPI: The ultimate sensitivity of this inspection technique is 2 to 5 mm long defects.
• WFMPI- Wet Fluorescent MPI: The ultimate sensitivity of this inspection technique is 1 mm long defects.
• WVMPI- Wet Visual MPI: The ultimate sensitivity of this inspection technique is 1 to 2 mm long defects.
• BWMPI- Black on White MPI: The ultimate sensitivity of this inspection technique is 1 to 2 mm long defects. This technique is preferred over the other due to the ease of photographic documentation and maintaining a high sensitivity.
  

  

4. Post Assessment

In the post assessment step, Allied Corrosion or the owner/operator will analyze the data collected from the previous three SCCDA steps for the following purposes:

• To determine if stress corrosion cracking mitigation is required and if so, prioritize those actions.
• To define the time interval to re-assess the pipeline segment.
• To evaluate and verify the decision model used to find stress corrosion cracking.

Our Integrity Management Team is ready to provide turn-key SCCDA services or we can perform any single or multiple step(s) that you, the owner/operator require.

The Allied Corrosion Difference

Our strong understanding of the potential destruction from a compromised pipeline allows us to deliver detailed Stress Corrosion Cracking Direct Assessment to complement any operator's Integrity Management program. Our comprehensive pipeline integrity and cathodic protection engineering services will keep your pipeline assets protected throughout its life-cycle.