Re: schedule of NDT inspection Hi,
I recommend you carry out complete thickness measurement (e.g., all elbows, either side of all butt welds, every 2 meters interval, 100% normal probe scanning at randomely selected locations, etc.) to determine the internal surface condition and extensive visual inspection to evaluate the external condition of the pipeline.
Then find out the maximum external and internal wall thickness loss for each line from the inspection results. Then calculate the maximum possible loss of wall thickness:
Maximum wall thickness loss = Nominal thickness - (Internal metal loss + External metal loss)
Then determine corrosion rate per per by dividing it by the number of years in service.
i.e., Corrosion rate per year = Total wall loss/No. of Years in service.
Calculate the minimum design thickness required for that line using barlow's equation and add safety factor (if any).
i.e., minimum required thickness = design thickness+ safety factor.
If the remaining thickness is well beyond the minimum required thciness and more than yearly corrosion rate, then you can schedule periodic on-line inspection yearly. Also you can schedule bi-annually if the remaining thickness is more tha twice the corrosion rate+ design thickness. You can schedule the inspection every 6 moths if the remaining thickness is too low but still above the minimum required thickness.
Replace the line when it is equal to or less than minimum required thickness.
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: hello ,
: i want, if anyone can help me to find out how to arrange the inspection's schedule - for gas plant and process area ??- according with....
: what code ...?
: my location has 30 years old.
: thanks daniel
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