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ESSO - Inspection and Repair Works on the Sulphur Unit 3/4 Chimney Basell - Flare Stack Inspection and Tip Replacement
ESSOThe Brief
The initial inspection was carried out by Delta’s in-house structural engineers who, through a complex The Delta Difference Following lengthy discussions with Esso engineers and their subsequent agreement with Delta’s repair proposal, the most economic and least disruptive solution for this site was to post tension the structure with an array of 39 circumferential bands constructed from rolled galvanised steel. Initial access was gained by installing a full circumferential fan protection shield near the base of the chimney to provide substantial protection for onsite plant personnel. One of the biggest concerns was to ensure that all personnel in the busy and congested process area were adequately protected. Access to the damaged sections of the chimney was gained through the installation of a full circumferential access scaffold at the 130m level. In addition, a (1000kg SWL) man riding winch was used to transport the men and materials up the chimney. A motorised platform was attached from the steeplejack modular scaffold to the initial 130m high scaffold providing unhindered access to the full height and circumference of the concrete windshield. Before the bands could be installed the vertical cracks were injected with Thixotropic resin while the spalled areas of concrete were repaired with Renderoc HB repair mortar. In addition to this, high pressure water was used to clean the chimney windshield and the upper section that exhibited etching was then coated with a fairing coat of Renderoc RP 252. The upper sections were given two coats of Fosroc Dekguard S to provide suitable protection from the elements and to prevent further damage as recommend by the manufacturer. All of the above repair works were carried out whilst the chimney was still fully operational. Delta saved Esso a stack by completing all work on time and on budget and more importantly by providing them with a comprehensive and detailed inspection and a cost effective, yet practical, total engineering solution for the required repairs.
BASELLThe Brief Delta International was asked to carry out a routine inspection of a 73m high twin riser flare structure which included a lattice support mast and associated guy stays. The planned maintenance included:
• NDT inspection
Delta carried out detailed engineering and non-destructive testing (NDT) inspection of the lattice support mast, guy wires, flare tip and associated riser and steam/pilot lines. The inspection revealed that essential repair work was required for the flare tips which had sustained thermal damage to the refractory lining, burner nozzles and thermocouples. Delta’s work was carried out during a scheduled maintenance shut down. Their own specially trained personnel ensured that all rigging methods and temporary works access equipment was carried out within the strict timetable. It was of paramount importance that Delta could plan for the expected as well as the unexpected; extending the scheduled maintenance down time would have been extremely expensive. Basell have extremely stringent safety, health and environmental standards and these, together with Delta’s own rigorous safety requirements for working at height, ensured that the flare stack project was safely completed without incident, on time and on budget.
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photographic survey, detected serious structural faults on the protective windshield, indicative of a lack of adequate reinforcement. The pattern of cracks meant that the windshield had broken down into a series of independent walls rather than the original uninterrupted cylindrical windshield. This was symptomatic of inadequate embedded steel reinforcement, which although meeting the design codes at the time of construction, no longer meets current legislation.
The Delta Difference