Repairs to Lightening Protection System on 120m Chimney
Introduction
Vertigo Specialist High Access Services (Vertigo) were engaged by Shell Australia Ltd to carry out an inspection and subsequent repairs to the damaged existing lightning protection system (LPS) on Stack 23 which is part of the CDU4 production facility at The Shell Geelong Petrochemical Refinery. The 120-meter high chimney is a reinforced concrete structure that vents gas combustion products. The LPS comprises a cast iron capping & peripheral coronal band at chimney top level in addition to three down conductors connected to earth.
As there is no fixed access on the structure, Industrial Rope Access methods (direct aid technique) was utilised to access the chimney top. The condition of existing LPS elements were ascertained and the system repaired as appropriate in accordance with AS1768 “Lightning Protection”. The work was performed during a shut down of the CDU4 facility in August 2003 and required close liaison with other maintenance contractors. This project draws on Vertigo’s expertise to provide remedial services in situations with problematical access issues and time constraints.
Scope of Work
The LPS inspection revealed deteriorated and missing sections of conductor, probably attributable to a direct lightning strike. The missing LPS components were replaced and an adequate level of lightening protection was returned to the structure.
Outcome
Vertigo successfully completed the LPS inspection and repairs within the shut down window and lightning protection was restored to the structure.