Shutdown planning for chemical plants:
what is different and what to do about it

01What is different about a chemical shutdown

A refinery turnaround usually takes one large unit down. A chemical or petrochemical shutdown often takes several smaller units down in a sequence set by shared utilities: steam, cooling water, flare, nitrogen and waste treatment. The sequence is a plan in itself, and a slip on one unit moves the rest.

The material is different too. Lined vessels, exotic alloys, specialty gaskets, agitator seals and instrumentation specific to one process carry lead times of 20 to 50 weeks and come from a short list of suppliers. There is no local stock to fall back on. A wrong alloy installed in a corrosive service is a safety event, so material verification matters more than on most refinery scopes.

The third difference is the plant itself. Batch units, continuous units and utilities share the fence, and the scope on each is owned by a different operations group. Planning has to hold all of it in one place or the shutdown becomes three shutdowns run in parallel by three teams.

02Scope: one list for the site

Build one scope list for the whole event, with the unit, the system and the owning operations group on every line. Freeze it once, site-wide, with one change process. Scope that is added by one unit after the freeze competes for the same crews, cranes and laydown space as every other unit; it has to be visible to the event, not just to the unit that added it.

For each scope item, record the work package number, the long-lead flag and the lead time in weeks. The long-lead list is the first output of planning and it drives the purchasing calendar.

03Sequencing across units

The scheduler holds the logic. The planning system holds the packages, material and cost each activity depends on, and tells the scheduler when something it depends on is late.

04Material: requisition to installation, by unit

Track every item from requisition and purchase order through receipt, staging, issuing and installation, with the unit and the package it belongs to. Three controls matter more on a chemical site:

1. Shortages measured against the activity date per unit, so a late seal on unit B is not hidden inside a site-wide received percentage.

2. Positive material identification and mill test reports tied to the item, not filed in a cabinet, so the alloy installed can be proven later.

3. Staging by package, so crews on three units do not draw from one pile.

Material is 30 to 40% of shutdown spend and tracking usually stops at the warehouse dock. On a multi-unit site that is where the losses, the duplicate orders and the expediting hide.

05Contractors and cost by shift

Several units mean several contractor packages and, often, several contractors for the same craft. Have every contractor estimate and report in one format inside the owner's system, so bids compare line by line and the daily cost report exists at the end of the shift. Track headcount planned against actual by contractor by day; on a sequenced shutdown a contractor running over on unit A is the earliest warning for unit B.

Scope changes should be approved before the work starts, with their hours and cost, and should move the forecast the same day. The forecast should be readable by unit and for the site.

06Execution: capture in the field

Progress, QA and discovery work are captured on the job, by shift, on a phone. Each package is closed within hours of the work, so the restart decision on each unit rests on packages that are closed, not on a list of jobs someone believes are done. On one site, capturing completion in the field with QA notified at once moved close-out from over 72 hours to under 24.

07Restart and carry-over

Restart each unit on its closed packages, reconcile its cost, and close its purchase orders. Then keep the packages. The next shutdown on the same unit should start from this event's packages, material lists and contractor performance, not from a blank sheet.

08Common mistakes on chemical shutdowns

1. Three unit plans and no site plan, so cranes, scaffold and specialist crews are double-booked on the same day.

2. One received percentage for the site that hides a critical shortage on one unit.

3. Specialty material ordered after the scope freeze, when the lead time was longer than the time left.

4. PMI results kept on sheets by part number, so the alloy installed in a corrosive service cannot be proven later.

5. Each unit's contractors reporting cost in their own format, so the site forecast is assembled once a week by hand.

6. Packages kept by the contractor, so the next shutdown on the same unit starts from nothing.

09The site-wide plan, in one page