Last updated: August 30, 2026 | By the editors at Reliable
The Short Version: A maintenance work order is the document that directs work execution once a requested job has been approved. It carries the tasks to be done, an estimate of the resources needed, the coordination and outages involved, plus safety requirements, job priority, and accounting information, a contents list spelled out in explicit detail in NASA’s facilities maintenance standard (NPR 8831.2F, section 5.6.1). If a technician can execute it and a reliability engineer can read the history later, it is doing its job.
What belongs on it is short to list and easy to shortchange: a unique identifier, the job steps, the labor and materials and tools, the safety requirements, a priority, the funding to charge, and space to record what actually happened at close-out.
If the work is on equipment, NASA’s sample form carries an equipment number, and that tag should exist in your hierarchy. Not every work order is on equipment. See How to Build an Asset Hierarchy in a CMMS: Structure and a Worked Example. If you are still choosing the system the work order will live in, see CMMS vs EAM: What’s the Difference, and Which One Do You Need?
How We Evaluated
This guide is independent editorial analysis based on publicly available government documentation. Reliable does not sell CMMS or EAM software, consulting, or certification and has no commercial interest in routing readers toward any particular platform. Reliable does not accept payment for inclusion in this guide. Vendors may sponsor enhanced listings with additional detail, but editorial rankings are independent. Read our editorial policy. The facts below come from NASA Procedural Requirements NPR 8831.2F, Facilities Maintenance and Operations Management (effective October 7, 2015; Chapter 5, Facilities Maintenance Program Execution), the U.S. Department of Energy Federal Energy Management Program Operations and Maintenance Best Practices Guide, Release 3.0, and OSHA 29 CFR 1910.147 for lockout/tagout.
What a maintenance work order is
Under section 5.6.1 of NASA NPR 8831.2F, the work order is the document directing facilities maintenance work execution once the requested work has been approved. It includes an estimate of the resources required (work hours by craft, materials, equipment, tools, and specialized support), the steps or tasks required to perform the job, and documentation of coordination and outages required. It should also carry safety requirements, job priority, job accounting information, and anything else management and the shops need to schedule, perform, and evaluate the work.
A request and a work order are not the same thing. Under 5.2.1, work requested is received and processed, and only if approved is it converted into a work order. Work that is disapproved goes back to the customer with an explanation or a request for clarification. The approval step is the line between a maybe and a directive.
Every work item also gets a unique identifier. NASA describes it under 5.5.3 as much like a serial number, assigned once and not changed even if the work is later combined with another item. That identifier is what lets the job be tracked through planning, approval, execution, and historical documentation. FEMP says typical CMMS functions may include work order generation, prioritization, and tracking by equipment or component, plus historical tracking sortable by equipment, date, and person responding. FEMP is also clear that a CMMS does not make decisions. It collects and stores information in an easily retrievable format so the O&M manager can act on it. When the work is on equipment, the equipment number on the form should come from a clean hierarchy; see How to Build an Asset Hierarchy in a CMMS if yours is not there yet.
What belongs on the work order
The list below is NASA’s. Execution contents come from sections 5.6.1 and 5.6.4. Unique ID comes from 5.5.3, priority also from 5.6.5, and completion space from 5.7.5.4. Those sections are not the whole NASA form. The sample work-order form in Appendix D is broader still: work-order number, work-item identifier, dates, facility, scope or title, and approval. This table is not an invented template and it is not a universal standard.
| Item | What NASA NPR 8831.2F says | Why it is there |
|---|---|---|
| Unique ID | Each work item gets a unique identifier, assigned once and not changed (5.5.3). | Lets the job be tracked from planning through history. |
| Tasks / steps | The steps or tasks required to perform the job, stated by craft (5.6.1, 5.6.4). | Tells the technician what to actually do. |
| Resources | Work hours by craft, materials, equipment, tools, and specialized support (5.6.1). | Nothing gets staged or scheduled without knowing what the job needs. |
| Safety | Confined space, lockout/tagout, oxygen depletion, chemical or explosive handling, fall protection, training and certification, and any task-specific requirements (5.6.1). | The job cannot be released safely without these called out. |
| Priority | Job priority so work can be ranked against other work (5.6.1, 5.6.5). | Sets what gets done first when resources are tight. |
| Accounting / funding | A funding citation and accounting data identifying which funds to charge (5.6.4.6). | Ties the labor and material to a cost record. |
| Coordination and outages | Documentation of coordination and required outages (5.6.1, 5.6.4). | Keeps the job from colliding with operations. |
| Completion space | Space for the technician to enter completion data (5.7.5.4). | The history is only as good as what gets recorded at the end. |
How to write one, step by step
1. Capture the request clearly
Work starts as a request, not a work order. Under 5.2.1, the request is received and processed, and it becomes a work order only if it is approved. A request that is disapproved goes back to the customer with an explanation or a call for clarification, so capturing enough detail up front is what keeps it from bouncing.
Route it through a work control function. NASA’s Work Control Center receives and logs work, assigns classifications, and tracks it (5.4.1). Whether that is a formal desk or one planner with a shared inbox, the point is that requests land in one place and get logged, not scattered across emails and hallway conversations.
2. Assign a unique identifier and do not change it
Give the work item a unique identifier at intake. NASA’s 5.5.3 compares it to a serial number: it permits tracking through planning, approval as a work order, execution, and historical documentation.
The rule that matters most here is that the identifier does not change once assigned, even if the work is later combined with another work item. If you renumber jobs midstream, you break the thread that connects a completed job back to the request that started it and forward to the history a reliability engineer will read next year. Assign it once and leave it alone.
3. Classify the work
Classification is how the work order gets sorted for approval, funding, and reporting. NASA lists several methods under 5.5.4: funds type, approval level, work elements, special interest, size, and method of accomplishment. Its work-element categories include PM and PM Finds, PT&I and PT&I Finds, Grounds Care, PGM, Repair, TC, ROI, Service Request, and Central Utility Plant O&M.
Those categories are NASA’s, built for NASA Centers. They are not a required list for every plant. Use them as a model for what classification does, then apply your own codes, the ones your CMMS reports on and your management actually reads. What you want is a small set of classes that route work correctly and roll up into numbers you use.
4. Write the job
This is where the work order becomes executable. Under 5.6.4, planning and estimating produces the job steps or phases for each craft, a list of required materials, identification of special tools or equipment, an estimate of the time for each phase, copies of sketches or drawings, identification of safety requirements and required outages, and allowances for staging, travel, site cleanup, and other job-related actions.
Safety is not a checkbox here. NASA’s 5.6.1 says safety requirements should include, but are not limited to, confined space entry, lockout/tagout, oxygen depletion, chemical or explosive handling, fall protection, and safety training and certification requirements. Call out the ones the task actually triggers. Under 5.6.4.6, each work order also carries a funding citation and accounting data identifying which funds to charge.
Assign a priority. NASA’s Table 5-2 is a sample priority system, not a universal ranking, and it is worth showing as a sample because it makes the categories concrete:
| Priority | Description (NASA sample, Table 5-2) |
|---|---|
| 1 Emergency | Safety of life or property threatened; immediate mission impact; loss of utilities. Begin immediately; divert resources as necessary; overtime may be authorized. |
| 2 Urgent | Required for continued facility operation or to restore a healthful environment; not life-threatening. Respond after current work but within a window set by the local Center, such as same day or within 4 hours. |
| 3 Priority | Supports the mission on a priority basis or meets project deadlines. Complete in order of receipt, mission work first. |
| 4 Routine | Can be scheduled routinely, subject to resource availability; may be consolidated by facility or zone. |
| 5 Discretionary | Desired but not essential to protect, preserve, or restore facilities and equipment; typically new work not tied to a mission milestone. |
| 6 Deferred | May be safely, operationally, and economically postponed; blocked by higher priority work, funds, site access, or conditions outside the maintenance organization’s control. |
The Urgent window is a local decision. NASA writes it as “such as same day or within 4 hours,” which means each Center sets its own number. Set yours deliberately and review the priorities periodically, as NASA directs.
5. Review and authorize
Authorization is typically a two-step process (5.6.3). The first step is an initial screening before job planning and estimating. The second is final approval and release of the planned and estimated work order for scheduling.
Final authorization is a real check, not a signature. Under 5.6.3.2, the review confirms the work order is responsive, complies with applicable safety, health, environmental, and security standards, is within the scope of the annual work plan, and is within funding and approval levels. On complex or critical jobs, the customer should review the work order for technical adequacy. When the reviews are done and funds are available, the work order is authorized for execution.
Not every job needs both steps. NASA allows trouble calls and small jobs to move through in one step, within the decision authority of the work reception desk, bypassing planning and estimating. Match the review weight to the job.
6. Close with completion data
The work order is not finished when the tool is back in the box. Under 5.7.5.4, when the work is completed and accepted, a completion report is submitted: record the completion in the CMMS, record the resources used, and close the work order. Capture the labor and material used, any unanticipated conditions encountered, a concise description of the work accomplished, and additional material used but not listed on the work order. This matters most when the original request was sketchy, because the close-out is where the real scope gets recorded. Shop supervisors should review the completion data.
Field reality sometimes diverges from the plan. Under 5.7.4, if field conditions or the effort and material required differ substantially from the estimate, the supervisor should check with the planner for an amendment. NASA suggests a 20-percent or greater increase over the estimate as the point where an amendment is warranted. Treat that 20 percent as NASA’s suggested threshold, not an industry rule.
One note on scope: NASA treats scheduling and shop load plans as a later execution phase, after the work order is prepared and authorized. This guide stays on writing the document. Once the work order exists and is authorized, scheduling is its own separate step.
A worked plant example
The following is illustrative and does not describe a real plant. Riverbend Processing runs a boiler feedwater pump, tag BFW-PMP-02, that has started weeping at the mechanical seal. Two pieces of work come out of it, and they are written differently on purpose.
The first is a full work order to replace the mechanical seal. It carries a work-item identifier assigned at intake, REQ-0417, which will not change, and a work-order number, WO-0417, on the approved document. Those are not the same field. Classification: Repair, priority 2 Urgent, with Riverbend’s local Urgent window set at same day. Tasks: isolate and lock out the pump (OSHA 1910.147 requires lockout unless tagout meets the full-employee-protection exception), drain the suction and discharge, pull the seal, install the replacement kit, refill, and run a leak check. Resources: 6 mechanic work hours, 2 operator hours for isolation, the seal kit and gasket set, and a portable hoist. Safety: lockout/tagout under OSHA 1910.147, covering energy-isolating devices, stored energy, and verification of isolation, written to the site’s energy-control procedure. The pit is flagged for a confined-space determination before anyone enters it, not a walk-by check. Accounting: charged to the utilities maintenance funding line. Coordination: a two-hour outage on the feedwater train, cleared with operations for the night shift. The form leaves space for the technician to record actual hours, actual parts, and anything found during the job.
The second is a small job on the same pump: retorque a leaking flange on the seal-flush line, well under NASA’s less-than-20-work-hours guidance. Riverbend writes it as a trouble call ticket rather than a full planned work order. The craft supervisor responsible for the TC reviews the task and specifies the safety requirements: lockout/tagout under OSHA 1910.147 (energy-isolating devices, stored energy, and verification) plus eye protection. It still gets a unique ID and is tracked for execution, but it is not planned and estimated in detail, because the cost of doing so would exceed the benefit. Neither of these is a purchase decision or a vendor choice. They are two documents, sized to two jobs.
Honest Limitations
NPR 8831.2F is NASA’s facilities maintenance and operations document. Compliance is mandatory for NASA employees, and it is written for NASA Centers and collateral equipment. It is not an ISO standard or a universal industrial requirement, so treat its structure as a well-documented model rather than a rule your plant is bound to follow.
The FEMP O&M Best Practices Guide is written for Federal facilities. Its principles travel well, but its context is government buildings and campuses, not process plants.
Several specific numbers in this guide are NASA’s, not industry figures. The sample priority table is explicitly a sample. The less-than-20-work-hours line for small jobs and the 20-percent-or-greater amendment threshold are NASA suggestions, attributed as such. We do not offer plant-wide benchmark percentages for work-order quality, because NASA and FEMP do not supply them. The unique identifier here is for the work item; asset tags are a separate hierarchy problem, covered in the asset-hierarchy guide.
Frequently Asked Questions
What is a maintenance work order?
A maintenance work order is the document that directs facilities maintenance work execution once the requested work has been approved. NASA defines it in NPR 8831.2F section 5.6.1. It carries the tasks required, an estimate of the resources needed, documentation of coordination and outages, and safety requirements, job priority, and accounting information. A request becomes a work order only after it is approved.
What should a maintenance work order include?
NASA sections 5.6.1 and 5.6.4 cover the execution contents: job steps or tasks by craft, resources (work hours by craft, materials, equipment, tools, and specialized support), safety requirements, job priority, funding and accounting data, and documentation of coordination and required outages. Unique identifier is 5.5.3. Completion space is 5.7.5.4. Appendix D’s sample form also has work-order number, work-item identifier, dates, facility, scope or title, and approval. Safety requirements can cover items such as confined space entry, lockout/tagout, chemical handling, and fall protection.
Who writes a maintenance work order?
In NASA’s model, planners and estimators normally prepare work orders. The exception is a trouble call ticket, which is handled through the work reception desk, and for which the responsible craft supervisor reviews the task and specifies the safety requirements. In a plant, the equivalent is usually a maintenance planner, with supervisors handling small jobs and trouble calls directly.
How is a work order different from a trouble call or a service request?
A work order is the approved, directive document that plans and estimates the job. A trouble call is a facilities maintenance or repair item, normally reported to the work reception desk, that is tracked for execution but is usually not estimated or scheduled because its scope is limited. A service request is new work requested by a customer, which may be a small job that needs no planning or a large one that does. Trouble calls and small jobs can be approved in one step, bypassing detailed planning.
Do small jobs need a full work order?
Not always. NASA notes that for small jobs, typically less than 20 work hours, the cost of detailed planning, estimating, and scheduling may exceed the benefit. In that case a trouble call ticket format is suggested instead, with the responsible craft supervisor reviewing the task and specifying safety requirements. The job still gets a unique identifier and is tracked for execution. The less-than-20-work-hours figure is NASA’s guidance, not an industry average.
What belongs in the work-order close-out?
When the work is completed and accepted, NASA section 5.7.5.4 calls for a completion report: record the completion in the CMMS, record the resources used, and close the work order. Capture the labor and material used, any unanticipated conditions encountered, a concise description of the work accomplished, and any additional material used that was not listed on the work order. Shop supervisors should review the completion data. If field conditions differed substantially from the estimate, an amendment may be needed.
Related Guides
- How to Build an Asset Hierarchy in a CMMS: Structure and a Worked Example
- CMMS vs EAM: What’s the Difference, and Which One Do You Need?
- How to Calculate Asset Criticality
- How to Start a PdM Program
- Lockout/Tagout Reference: 29 CFR 1910.147
Sources
- NASA – Facilities Maintenance and Operations Management (NPR 8831.2F) (Chapter 5, work-order preparation)
- U.S. Department of Energy, Federal Energy Management Program – Operations and Maintenance Best Practices Guide, Release 3.0 (CMMS work-order functions)
- OSHA – The control of hazardous energy (lockout/tagout), 29 CFR 1910.147 (energy-isolating devices, stored energy, verification)
