For a recent 42-inch-diameter pipeline shutdown, the contractor provided steel pipe to match the outside diameter of the existing prestressed concrete cylinder pipe that was to be connected to. Only because the engineer was on call through the work was the team able to gather onsite, coordinate material requirements with suppliers, schedule emergency welding, and design a modified concentric reducer in the field — all in less than three hours. The quick response allowed the owner to bring the system back online on schedule and without service interruption, despite the initial scare.
purpose here is for all to see, understand, and accept the proposed shutdown design and sequencing. • Pre-shutdown meeting — This is generally held about two to four weeks before the proposed shutdown. This will be the first meeting the contractor is incorporated into the discussion (assuming design- bid-build procurement), and he/she should actually lead this meeting. The purpose is for the engineer and owner (operations, maintenance, and inspection at minimum) to hear the contractor’s specific plan and to ensure it aligns with design criteria and intent. The contractor should bring detailed plans for the approach including a schedule and sequence, materials list, identification of responsibilities, and specialty personnel needed. For example, for a 36-inch-diameter pipeline shutdown that had to be completed in less than 72 hours to replace existing bar-wrapped concrete cylinder pipe, a final shutdown meeting and field walkthrough was not conducted with the contractor. Despite several discussions about connection alternatives and general team buy-in of the approach, no one understood that part of the contractor’s proposal was to replace less pipe than designed to connect at an existing joint, once found in the field. The result was confusion during construction and a contrac- tor installing 26 feet rather than 68 feet of new steel pipeline, chang- ing thrust restraint mechanisms and requiring an emergency design response. This likely would have been avoided with a pre-shutdown walk through onsite. • Final preparation meeting —Afinal meeting should be held a day or two (at most) before the shutdown is to take place. Ideally, this should be held on location and jointly led by the contractor and inspector, as these two stakeholders need to be working in harmony. This provides the owner and engineer an opportunity to put eyes on the site, identify conflicts, and walk through the sequence. Without a doubt, things will be seen here that have been overlooked or left undiscussed in previous
meetings. Further, this gives all parties a final “go/no-go” approval, which should be documented as part of a final checklist. Checklist To be clear, no checklist can cover every situation on any potential project. However, that is not really the intent of checklists. The pur- pose of such an exercise is to ensure that while focusing on the highly technical and unique project elements, you don’t overlook the small, standard, day-to-day stuff. Ideally, every owner develops their own shutdown checklist so that it can be specifically developed around your operation. Only then can it truly match your nomenclature, operating procedure, and organiza- tion structure. However, the lack of a client-developed checklist is no excuse to skip the exercise. In shutdown planning, a checklist should be required before final “go” approval but should be started at the first meeting (conceptual design) and updated at each subsequent meeting until completion just before work commences. The final document should be maintained in project files, kept onsite during work, and include sign-offs from all project The first two practices identified above (meetings and checklists) are primarily planning activities — that is, work before the shutdown ac- tually takes place. Having the proper inspection personnel onsite and ensuring the design engineer is on-call and readily available during the shutdown are, conversely, construction tasks. stakeholders. Inspection It is vital that inspection personnel be involved during the design pro- cess for any large pipeline shutdown. It is also critical that the inspector hear directly from the engineer what the design intent is, what critical elements must be monitored, and what can negatively impact the sys-
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csengineermag.com
march 2018
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