At some point, most plants will have a scheduled outage. The time, money and effort devoted to planned shutdowns can be extreme. Plant teams must make every effort to properly prepare, execute and support the shutdown.
Scheduled outages may be plantwide, occur through different sections or be cold or running. Job plans for each asset is a prerequisite. According to Shon Isenhour, a partner with Eruditio and a holistic reliability solutions expert, job plans decrease the time to complete a job by half. They also decrease costs versus emergency repairs by three to seven times. Following the steps outlined below will help ensure that a plant’s next outage will be successful.
Step 1: A comprehensive list
A checklist with every piece of equipment involved in the outage should be available for review. Every stakeholder should examine this list to ensure nothing is missing. Examples of assets for most plant checklists include:
- Dust baggers.
- Mixers and blenders
This checklist should be periodically updated to add equipment installed since the last shutdown. It should also note:
- Equipment difficult to take offline in the past
- Bad actor assets since the last outage
- Special equipment such as cranes or generators needed to complete the required work.
This information should be included in the job plan for each equipment type.
Step 2: Have it in inventory
Ensure that all replacement parts, accessories and rebuilt equipment are in stock before the shutdown. The last thing any team needs is to have staff on hand to conduct maintenance, replacements and new installations only to be held up waiting for rebuilt equipment to return from a shop.
The team should encounter no surprises. Inventory should be up to date well before the outage date. Environmental controls are part of this inventory, including pressure gauges, temperature sensors and flush line components. Sealing equipment, such as packing, process seals, oil seals, new lubricants and lantern rings should be in stock and prepared for installation.
Step 3: Safety first
Safety should be the top priority during any outage. Before beginning work, all lock out/tag out (LOTO) procedures should be followed and personnel must wear all required personal protective equipment (PPE) (see Figure 1).
Because equipment is shut down, personnel may have a false sense of security. However, PPE is still required, especially for situations in which machinery or piping may retain hazardous, hot or corrosive liquids. Team leaders should review task and safety requirements with personnel participating in the work, including temporary staff onsite who may not be as familiar with this location’s LOTO and PPE rules. A zero-tolerance LOTO and PPE policy should be enforced.
Step 4: Within current specifications
Double check that all equipment (new and rebuilt) is within current operating parameter specifications. When assets were specified, they met the requirements of the process at that time. Condition changes, such as fluid temperature, flow requirement or process fluid pH must be considered. Different parts or different equipment may need to be used.
For example, water flow from when a pump was specified was 100 gallons per minute. During operation and plant growth, the requirement at shutdown is 500 gallons per minute. Perhaps a larger pump should be installed. An outage is an ideal time to make this type of replacement.
Step 5: Inspect before installation
Personnel should inspect all equipment before anything is installed; look for wear or damage. Installing new components into a worn piece of equipment is almost always counterproductive. Demise of the new components begins immediately. Examples of this include:
- Packing installed in a pump with a worn shaft or sleeve or a damaged stuffing box wall will immediately begin to wear.
- With extreme damage, successful installation may not be possible.
- Installing a new mechanical seal into a system with a failing bearing or bearing isolator means the mechanical seal’s life will be shortened.
- Installing a new impeller on a worn shaft or with improper clearances because of casing wear or damage will result in poor operation and incorrect flow.
Step 6: Precise installation
While this step seems obvious, improper installation happens all the time. Reliability begins with the asset selection and correct installation. If installed imprecisely, failure begins at startup.
Installation issues include:
- Soft foot — A soft foot exists when not all a machine’s feet sit flat on the supporting base, so that tightening the foot bolts distorts the machine case. This can make a machine difficult to align and a distorted case can result in poor overall machine performance, according to EASA.
- Improperly set packing
- Bearings installed with a hammer or without being properly heated
- Incorrect tightening of bolts or other fasteners
- Installing the wrong component
- Using the wrong lubricant.
Properly following job plans help prevent premature failure because of installation problems. An example of ways to properly install components is to use tools to install compression packing. Using tools and carefully following the correct job plan steps every time results in precise installation and provides the longest life for each component or asset (see Figure 2).
Step 7: Inspection before restart
The plant team should give everything one more look before restarting the plant or process. Even when every step is taken and every job plan is followed, stuff happens. A motor is bumped during work on another piece of equipment, causing misalignment. Housekeeping staff accidentally hits a piece of equipment. A wrench left on an asset may have fallen.
These are a few examples of problems that could occur after proper installation. A quick review of all assets worked on helps prevent these types of problems. After the review, each asset should be restarted according to the proper procedures (refer to the manufacturer’s instructions or job plan for startup).
Look for more ways to improve and simplify
Outages are excellent opportunities to look for areas that can be improved by new or updated technology. Measurements can be taken, and new equipment considered for the next shutdown. These improvements can include:
- Adding different seal types
- Adding new bearing isolators to prevent lubricant leakage or contamination
- Updating bushings and packing types for improved sealing and shaft protection.
Benefits of an onsite manufacturing representative
Having a manufacturing representative onsite may help speed up the outage process and ultimately save the plant money. In one Southeast paper mill, maintenance teams were replacing the packing on a digester every week. A maintenance rep suggested replacing the packing and stayed on hand to make sure the packing was installed and seated correctly. This repacked digester operated successfully from January to April of that year, when an outage occurred. This saved the plant more than $98,000 during these four months.
An onsite rep can:
- Look at specific problems the team may be having
- Help troubleshoot other equipment issues
- Inspect and measure before installation to ensure that everything is within specifications
- Examine all rotating assets and make sealing technology suggestions
- Ensure that the equipment and technology are installed correctly
- Make suggestions for upgrades that may save time and money.