Potential for Improvements—Planning

There were three separate plans: the first for operational activities, a second for project work, and the third being the main plan for maintenance work.

It was not possible to coordinate and manage changes that would occur from time to time in individual plans. Resource balancing was not global and thus not optimal. Equipment status charts were maintained separately by operations, inspection, and maintenance. This made it difficult to get an overview, resulting in avoidable delays.

Some items of work could have been reduced or eliminated during the work list challenging process. For example, in order to measure wall thickness of heater tubes ultrasonically, they erected scaffolding along the walls of the heater cells. Then they scraped and cleaned the tubes. Oil firing produced sulfur deposits on the tube surfaces which were quite acidic and posed a health hazard to people working inside the heater. They cleaned these using mechanical scrapers before allowing the main group of workers inside the furnace cells. Once the heaters were scaffolded, they ground spots on the tubes to bare metal, where the measurements were required. Records showed that not even a single tube had ever been rejected in the past as a result of these measurements.

The only tubes that needed replacement were those that were damaged by flame impingement. None of the 320 tubes (6 5/8" dia., 44' long, and 7/16" wall thickness) showed excessive loss of metal during the current inspection. All readings were within 10% of nominal thickness, while the rejection limit was 50%. These readings did not help make replacement decisions, so it was unnecessary work. Convincing the Regulator, however, was a different ball- game.

Some weeks later, in a frank discussion with the Regulator, the refinery tabled all the findings over the years. With these, they convinced the Regulator to let them reduce the number of measurements significantly. Instead of measurements every half meter over the whole length of the tube, the Regulator permitted them to limit measurements to the most severely affected locations on the tubes. This reduced the ultrasonic measurement work by about 70%.

For future shutdowns, I suggested a switch over to natural gas firing for two days prior to shutdown. This change would help vaporize the acidic sulfur deposits and eliminate the need for extensive cleaning. Together, these changes would reduce heater work duration by 16 hours. Gas firing was expensive, and the difference between the cost of gas firing and reduction in maintenance costs was estimated at US$15,000. This increase was minor, but the reduction in health risks was quite considerable.

A total of 88 non-return valves of varying sizes and pressure ratings were opened for inspection. Of these, 19 had damaged internals and 6 others were fouled and needed cleaning. Of the 19 valves with damaged internals, at least 50% of the damage occurred while dismantling them. Additional pre-shutdown non-intrusive inspection could have identified many of the fouled or defective valves. The number of valves to be examined could have been reduced significantly.

The software package used for planning and scheduling was quite satisfactory as far as its main function was concerned. However, it did not produce Gantt charts or lists of pending items by zone. All these were done manually by the supervisors themselves. A different software package could eliminate

Turnaround Performance Improvements 2 75

such time-consuming manual work.

Evacuation drills were not part of the plan. In a shutdown of this size, with nearly 500 contract workers at site, it is not sufficient to do a classroom safety induction. Fire and gas alarm conventions differ in different companies and escape routes need familiarization. Evacuation drills are necessary to ensure that people can get away safely, should there be an incident. A common misconception is that such drills would result in a significant loss of productive time. If these are conducted just prior to a planned break, such losses can be minimized.

 
Source
< Prev   CONTENTS   Source   Next >