February 28, 2020 at 10:36 am #117
There can be faced many problems during revamping the process plant; the following are but not limited to, some problems.
1. errors in engineering documents like PFDs, P&IDS, specification sheets etc. these should be carefully reviewed and compared with the existing plant data.
2. During execution, plant physical layout may restrict the installation and replacement of equipment. In addition, piping ties ins can be weld with wrong lines or locations.
3. Restriction of old lines to the new lines.
4. Wrong orifices or instrument sensors as compare with the existing size.
March 2, 2020 at 4:27 pm #119
In addition to the above;
1. Hand over of the equipment/pipelines for the tie in jobs might be difficult. Hydrocarbon freeing through steam out or Nitrogen purging or any other method can be difficult because of different interconnected circuits.
2. Some circuits can be hand over for hot jobs but some can not but it is better to completely make plant free of the Hydrocarbons prior to starting the hot jobs, otherwise there will be dangers of fire.
3. For tie in jobs, it better to short the circuit as maximum as possible and insert blinds to the nearest flanges. Don’t rely on isolating valves only, provide blinds for safe execution of the job.
4. For tie inns outside the battery limit, coordinate with interfering plants and steam out/water flush/nitrogen purge during units shut down. Make the arrangements, prepare work instructions and field visit in advance of the unit shutdown. After the shutdown of all plants and insertion of blinds at battery limits, it will be difficult to flush out the outside battery limit lines.
March 4, 2020 at 5:19 pm #120
In addition to above;
1. Direction of new valves, control valves and non return valves might be wrong.
2. LG, LT fittings or inlet outlet lines of new equipment might be misaligned.
3. Due to welding joints with the existing lines , welding slug or other wastes can chock or block the process. So flushing Will be required.
4. New pipelines, equipment and supports with existing unit will restrict the walkways and making the plant congested.
5. Another big challenge is the internal modification of process equipment. It becomes very difficult to replace,modify or add any part inside the column, vessel or reactor.
E.g in reactor where very sophisticated trays, mixing parts are used we have seen mistakes from the vendors as well. So confirm each part even small nut bolts from drawings and then go for job. These jobs preferably should be supervised by the specialist of the field.
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