CLIENT
A oil and gas major client, the second largest integrated oil & petroleum company in Southern Africa, in conjunction with a major steel fabricator.
HISTORY
The Refinery identified a need for longer lasting protection for
their buried steel structures when inspection of the Bullets
revealed that the specified coating was blistering owing to
Cathodic disbondment within 5 to 6 years. (The required
design life expectancy was 40 years)
The location is a high rainfall, marine industrial environment
which rates as a C5 on the Corrosivity Index. In addition, the
steel bullets are buried in coastal chloride-rich soils.
SCOPE OF WORK
The LP Gas Bullet comprises of three sections welded
together to a total length of 63ms, and 5.5m diameter,
fabricated from 50 mm thick carbon steel and weighing 357
Ton. The LP Gas Bullet was coated in 3 Sections and
transported to the Refinery where the Bullet sections were
welded together on site and final touch ups took place before
the Bullet was “mounded” or buried in the ground.
- Grit blast to ISO 8501-1, cleanliness standard SA 2½
- Apply Polyglass VEF to a nominal DFT of 1500 and
minimum of 1000 µm - High-voltage Spark Test to 10kV -DC
APPLICATION DATE
August 2007 – Completed in 4 weeks
COATING SYSTEM & SELECTION CRITERIA
The longest possible anti-corrosion life expectancy, with the
lowest risk of failure. The Refinery achieved this by:
- Revising the design requirement for the coating of buried structures.
- Comparative performance testing to destruction by an independent third party on various coatings, which were then ranked in terms of long-term anti-corrosion ability
- The material with the best technical performance was recommended, based on the laboratory test results,
- The lowest Life Cycle cost was ranked as more important than lowest initial cost – this change in philosophy was a major departure from previous selection criteria. (The best performing coating was not the most expensive.)
- The client won the Corrosion Institute’s Annual Award in 2007 for the research they did on coating selection for this project.
- Further to the successful completion of this project, Polyglass VEF has been specified as standard for all buried structures by the Refinery, and the Corrosion Protection Refurbishment of old buried steel has started.
