A unit turnaround (TAR) provides opportunities for plants to execute capital and maintenance projects or make tie-ins during an outage window. This downtime is costly not just in terms of lost production from the unit being down but also in the many hours of overtime paid to both plant employees and contractors brought in specifically for the TAR. As a result, proper planning is critical to maximizing contractors’ efficiencies and minimizing overtime. Questions and finger pointing do not get piping and equipment installed in a timely manner. The key to the successful implementation of a project during a short outage window is having thorough, detailed work packages. These packages provide the instructions for order-ing material, field preparation work, field installation and documentation for the plant technical information group.
The success of a planned TAR will hinge on the quality and comprehensiveness of the information provided in the work packages. In order to develop a thorough package, the scope of the job must be understood by personnel developing the package. A field walk and a review with maintenance and operations personnel are essential to understanding how to execute the job. In addition, the work package must be conscious of the HS&E aspects of the job. Any one of these items can cause big delays in execution.
Once the preliminary review of the scope has been assessed, the necessary items of the work package can be completed. Whether the work packages are for a line replacement, jump-over or vessel tie-in, any work performed on process equipment should at a minimum contain seven distinct documents:
1. Scope of work — A detailed work scope for each work package will provide a sequence of events from pre-TAR activities to fabrication instructions with QA hold points to post-TAR activities.
2. Redlined P&IDs — All relevant P&IDs should be redlined to clearly show the modifications being performed on the process.
3. Drawings/ISOs with bill of materials, including line list and tie-in list — All work packages should include a set of IFC (issued for construction) drawings and a bill of materials.
4. Maintenance of Certification (MOC) — If the work to be performed is considered an alteration, then approved and signed-off process safety management (PSM)-compliant documentation should be included in the work package.
5. Weld Quality Control Form (WQCF) — Most turnaround work will require welding on pressure-containing equipment. A WQCF, along with the required NDE procedure(s) to be used, should accompany all work packages to ensure the welding procedure is clear.
6. Tie-in tags — Tie-in tags should be installed on the equipment or piping requiring alterations prior to the TAR. These tie-in numbers will also be designated on all ISOs and P&IDs associated with the job.
7. Checklist — A checklist should be filled out for each job to verify all documentation has been completed for the particular TAR package. This checklist should include: P&ID redlines, a line list with design temperature and pressure, proper pipe specifications, support details, specialty items, a bill of materials, paint/insulation/heat trace specifications, instrumentation elements, control valve bolt patterns and actuator clearance, valve hand-wheel orientation and pinch points, insulation clearance, dead legs and pocketed lines reduced or eliminated, orifice plate straight runs of pipe, minimized field-fit welds, piping isometrics matching P&IDs, piping plan and sections, a properly populated tie-in list, the types of tie-ins identified and tagged in the field, prep sketches, post-weld heat treatment, a properly revised drawing register, nipolets for vents and drains, orifice root valve orientation and rod out, gussets for vibrating service, and demo drawings and/or pictures.
The checklist should be signed off on by the designer(s) and project engineer, and provided to the TAR planning group for proper planning and execution.
Taking time in the TAR planning cycle to ensure thorough work packages are developed for each project to be executed during the outage is guaranteed to save you time, which will save you money and headaches during your next turnaround.
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