--- title: "Pre-Startup Safety Review | Intro to Chem Eng" description: "Pre-startup safety review is the final check before a chemical process starts, confirming equipment, procedures, and training are ready in Intro to Chemical Engineering." canonical: "https://fiveable.me/introduction-chemical-engineering/key-terms/pre-startup-safety-review" type: "key-term" subject: "Intro to Chemical Engineering" unit: "Unit 12" --- # Pre-Startup Safety Review | Intro to Chem Eng ## Definition A pre-startup safety review is the final safety check done before a new chemical process or piece of equipment is started. In Intro to Chemical Engineering, it confirms the system was built, installed, and prepared safely. ## What It Is A pre-startup safety review, or PSSR, is the last formal safety check before a new or modified chemical process is allowed to start up in Intro to Chemical Engineering. It asks a simple question: is this system really ready to run, not just on paper, but in the plant. The review happens after construction or modification is finished, but before chemicals are introduced and operating conditions begin. That timing matters. By this point, the design work should be done, the equipment should be installed, and the operating procedures should be written. The PSSR checks whether the real system matches the intended design and whether the team is ready to operate it safely. A good PSSR looks at several things at once. You check that equipment was installed correctly, that piping and valves match the design, that relief devices and alarms are in place, and that instrumentation works the way it should. You also verify that safety information, operating procedures, and training are complete. If a pump is connected backward, a sensor is missing, or the operators have not been trained on the shutdown steps, the process should not start yet. This is more than a paperwork exercise. In chemical engineering, small startup mistakes can become leaks, overpressure events, reactions that run away, or exposure to hazardous materials. The PSSR is a barrier between construction and operation, so it catches problems when they are easiest to fix. It is the point where the team moves from "we designed it" to "we can run it safely." The review is usually multidisciplinary because no single person sees everything. Engineers, operators, maintenance staff, and safety personnel each notice different gaps. An engineer might spot a design mismatch, while an operator might notice that the procedure does not match the real layout. That mix of perspectives is what makes the review effective. In many Intro to Chemical Engineering examples, the PSSR fits into a larger process safety management system. It is tied to process safety information, hazard identification, mechanical integrity, and management of change. If any of those earlier steps were weak, the PSSR can reveal the weakness before startup turns it into an incident. ## Why It Matters Pre-startup safety review matters because it is one of the last chances to catch failures before a chemical process becomes active. In Intro to Chemical Engineering, a process is not considered ready just because the equipment is built. It also has to be verified, documented, and approved for safe operation. This concept connects design to real-world operation. A heat exchanger, reactor, pump, or distillation unit can look correct on a drawing and still be unsafe if a valve is missing, a line is misrouted, or the operators do not know the startup sequence. The PSSR is where you check that the final plant matches the intended process and that the people using it have the information they need. It also reinforces how process safety is different from routine quality control. You are not just asking whether the product will come out right. You are asking whether the system can start without creating pressure, temperature, or exposure hazards. That distinction shows up a lot in chemical engineering problems, especially when the course discusses process safety management, mechanical integrity, and management of change. If you can recognize what belongs in a PSSR, you can trace where safety failures happen in a process timeline. That skill helps with case studies, lab scenarios, and process descriptions where you have to identify the missing barrier or explain why a startup should be delayed. ## Connections ### Process Safety Management PSSR is one piece of the larger process safety management system. PSM covers the full lifecycle of a process, while the PSSR focuses on the final readiness check before startup. If a question asks where the review fits in the bigger safety picture, this is the umbrella term to connect to. ### [Management of Change](/introduction-chemical-engineering/key-terms/management-of-change) Management of Change deals with modifications to a process, equipment, or procedure. A PSSR often follows a change or a new installation, because the team needs to verify that the change was carried out safely and that nothing was missed during implementation. The two steps work together. ### [Mechanical Integrity](/introduction-chemical-engineering/key-terms/mechanical-integrity) Mechanical integrity is about making sure equipment is maintained and reliable. A PSSR checks whether that equipment is actually installed, tested, and ready to operate. If mechanical integrity is weak, the startup review may expose leaks, broken instruments, or other failures before chemicals are introduced. ### Hazard Identification Hazard identification is the process of spotting what could go wrong in a system. The PSSR uses that idea in a final, practical way, checking for leftover hazards before startup. You can think of it as hazard identification applied right at the handoff from construction to operation. ## On the AP Exam A quiz or short-answer question might give you a startup scenario and ask whether the process is ready to begin. Your job is to identify what the pre-startup safety review would check, such as installed equipment, completed procedures, alarms, training, and documentation. You may also need to explain why startup should be delayed if a safeguard is missing. In a case study, you might trace the order of events after construction or a process change and decide where the review fits. If the problem mentions a new reactor, a modified piping line, or a rebuilt control system, a strong answer will connect the PSSR to process safety management and management of change. Look for the gap between "built" and "safe to operate" and name the missing verification step. ## pre-startup safety review vs Safety Audits Safety audits and PSSRs both check safety, but they are not the same. A safety audit is broader and may happen on an ongoing schedule across the plant. A pre-startup safety review is narrower and happens right before a new or changed process starts, with a focus on startup readiness. ## Key Takeaways - A pre-startup safety review is the final safety checkpoint before a chemical process or piece of equipment goes into operation. - It verifies that the installed system matches the design, the safeguards work, and the operators are ready to run it safely. - The review is part of process safety management, so it connects to hazards, changes, equipment integrity, and startup planning. - If the review finds missing training, wrong installation, or incomplete documentation, startup should pause until the problem is fixed. - In Intro to Chemical Engineering, the PSSR is the bridge between construction and real plant operation. ## FAQs ### What is pre-startup safety review in Intro to Chemical Engineering? It is the final check done before a new or modified process starts up. The review confirms that equipment is installed correctly, safety systems are in place, procedures are ready, and people have been trained. ### What gets checked during a pre-startup safety review? Typical checks include equipment installation, alarms, interlocks, relief devices, operating procedures, training, and documentation. The team is looking for mismatches between the design and the actual plant setup. ### How is a pre-startup safety review different from a safety audit? A safety audit is broader and usually looks at overall compliance or plant safety performance. A PSSR is narrower and happens right before startup, so it focuses on whether the process is ready to run safely right now. ### Why would a chemical process fail a pre-startup safety review? It might fail if a valve is installed incorrectly, a sensor is missing, the procedure does not match the equipment, or the operators have not been trained. Any of those problems can make startup unsafe. ## Related Study Guides - [12.2 Process safety management](/introduction-chemical-engineering/unit-12/process-safety-management/study-guide/c9ADqEOkFhbUqZ7B) ## About This Document Canonical Fiveable pages are available as Markdown at the same path plus `.md`. - [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns - [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing - [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`) - [MCP server for AP teachers](https://fiveable.me/mcp/teachers): a teacher's classes, assignments and AP-rubric grading (`https://fiveable.me/api/mcp/teacher`) ## Structured Data ```json {"@context":"https://schema.org","@graph":[{"@type":"LearningResource","@id":"https://fiveable.me/introduction-chemical-engineering/key-terms/pre-startup-safety-review#resource","name":"Pre-Startup Safety Review | Intro to Chem Eng","url":"https://fiveable.me/introduction-chemical-engineering/key-terms/pre-startup-safety-review","learningResourceType":"Concept explainer","educationalLevel":"AP® / High School","about":{"@id":"https://fiveable.me/introduction-chemical-engineering/key-terms/pre-startup-safety-review#term"},"audience":{"@type":"EducationalAudience","educationalRole":"student"},"dateModified":"2026-07-03T02:22:28.064Z","isPartOf":{"@type":"Collection","name":"Intro to Chemical Engineering Key Terms","url":"https://fiveable.me/introduction-chemical-engineering/key-terms"},"publisher":{"@type":"Organization","name":"Fiveable","url":"https://fiveable.me"}},{"@type":"DefinedTerm","@id":"https://fiveable.me/introduction-chemical-engineering/key-terms/pre-startup-safety-review#term","name":"pre-startup safety review","description":"A pre-startup safety review is the final safety check done before a new chemical process or piece of equipment is started. 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