alexisa
Mechanical
- Aug 5, 2003
- 2
Corrosion issues on buried piping sections up to 48" NB - Excavation costs for inspection of buried un-piggable piping are prohibitive long term. We are looking at ILI for parts of the buried piping we can access (tethered crawler tool via spool removal), but this is only for decision making further down the road. Total buried pipework circa 400m, up to 5m depth.
Options we are considering are: 1) Open up all buried piping sections in open trenches, 2) Going up and over tank bunds, then overground, 3) Excavate, inspect and replace buried sections with lined pipe, 4) Continue with periodic inspections. We are looking at a life extension of the tank farm facility until 2040 (20 yrs).
Option 1 is problematic for traversing earthen bund walls and maintaining containment during construction. Option 2 has hydraulic limitations and will likely increase opex for additional pumping. Option 3 may be prohibitive cost-wise for inconel or other pipeline trims. Option 4 (do nothing) is possible, however causes significant, on-going site access constraints (road crossings etc.) as well as control of works issues, and requires repetitive tank outages (loss of ullage) on an on-going basis.
From civil works perspective, Option 1 will be significant, particularly for bund wall crossings, but also as trenches will likely need retaining walls as well as major structures for crossing tank bunds. Option 2 will be least significant with structural pipe bridges and supports taking up more costs. Option 3 will also have significant excavation costs but not the civil element for option 1.
Does anyone have any experience or insights that may be usefull?
Thanks
Options we are considering are: 1) Open up all buried piping sections in open trenches, 2) Going up and over tank bunds, then overground, 3) Excavate, inspect and replace buried sections with lined pipe, 4) Continue with periodic inspections. We are looking at a life extension of the tank farm facility until 2040 (20 yrs).
Option 1 is problematic for traversing earthen bund walls and maintaining containment during construction. Option 2 has hydraulic limitations and will likely increase opex for additional pumping. Option 3 may be prohibitive cost-wise for inconel or other pipeline trims. Option 4 (do nothing) is possible, however causes significant, on-going site access constraints (road crossings etc.) as well as control of works issues, and requires repetitive tank outages (loss of ullage) on an on-going basis.
From civil works perspective, Option 1 will be significant, particularly for bund wall crossings, but also as trenches will likely need retaining walls as well as major structures for crossing tank bunds. Option 2 will be least significant with structural pipe bridges and supports taking up more costs. Option 3 will also have significant excavation costs but not the civil element for option 1.
Does anyone have any experience or insights that may be usefull?
Thanks