The topic of human factors (HF) is often times misunderstood and sadly sometimes not even a thought during a Process Design/Engineering Review or a Process Hazards Analysis. Now I know some of you will scream… “we are not a refinery” so there is no need for us to go to this level in our efforts to ensure human factors are a core component of our process design. But this “Design and Engineering Practice (DEP)” from an international refiner is an absolute must-read for those who want to get serious about human factors when planning/designing/constructing a new process. Heck, this is a must-read for anyone involved in process safety and wants to gain a much better understanding of what HF’s are all about. Here is the scope of this DEP:
This DEP specifies requirements and gives recommendations for applying Human Factors Engineering (HFE) principles to the design and layout of valves for both onshore and offshore facilities and equipment. It includes the following:
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- A procedure for analyzing and then classifying the criticality of valves for a specific application;
- Guidance on selection of the appropriate type of valve operator/actuator;
- HFE design requirements for the location and orientation of manual valves.
Other highlights that we should pay attention to: (emphasis by me)
2.1 BACKGROUND
This is one of a series of DEPs that support the implementation of Human Factors Engineering on projects. The design requirements (4) with regard to valve location and orientation are mainly applicable to manual valves. However, they also apply to motorized, mobile actuator or otherwise remotely operated valves which could need rapid or frequent manual intervention to override and manually operate them, or where visually checking their status forms part of an HSSE critical activity.
Accessibility requirements of instruments and their associated valves are addressed in DEP 30.00.60.20-Gen. and DEP 32.31.00.32-Gen.
My favorite part of the DEP is: (emphasis by me)
VALVE CRITICALITY ANALYSIS
A Valve Criticality Analysis (VCA) shall be conducted during the early DEFINE phase, when the PEFS (P&IDs) first become available. This ensures that:
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- the results can be factored into valve procurement and piping and layout design;
- space for physical access and other design requirements needed to identify, operate, maintain and inspect valves can be integrated into layout drawings and 3D models.
VCA session results shall be appropriately documented. The initial classification of valves and selection of appropriate actuators may need to be reviewed and revised when more detailed information becomes available at a later stage in the design or implementation of a project.
The associated access and location requirements for each valve type and HFE design criteria presented in (4) shall be included in the appropriate project specifications and contractual documentation. Deviations shall require the approval of Operations and the HFE TA.
Criticality ratings of valves shall be included on PEFS (P&IDs), and if a 3D CAD model is being used for design, Category 1 valves shall be coded therein (e.g. by color coding 3D shapes).
Compliance shall be validated throughout the EXECUTE (Engineering, Procurement and Construction) Phase of the project and during pre-start-up audits.
VALVE CRITICALITY RATING
General
Valves shall be rated by criticality. The following three (3) categories are recommended.
These criteria shall be reviewed and agreed upon prior to starting the analysis. The final criteria shall balance ease of access for operations against maintenance access and project costs. Risks to health and safety, including risk of human error, shall be kept as low as reasonably practical.
Category 1 (C-1) valves
Category 1 (C-1) valves include those essential to normal or emergency operations where rapid and unencumbered access is essential. The height, reach distances and visibility shall conform to the “preferred” location as outlined in (4).
These are valves that meet any or all of the following criteria:
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- Valves essential to production;
- Valves essential to process safety or asset integrity;
- Particularly large valves;
- MOVs with high failure rates and which require rapid corrective action;
- Valves being used in a service or under operating conditions where the failure rates are not known or may be unreliable.
- Valves where consequence of failure to obtain quick access would be serious (e.g. process shutdown and/or damage to facilities or personnel);
- Valves for which the expected routine operation, inspection and/or maintenance is more frequent than once every 6 months.
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Category 2 (C-2) valves
Category 2 (C-2) valves are those that are NOT critical for normal or emergency operations but are used during routine inspection or maintenance activities. These are valves that meet any or all of the following criteria:
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- Valves associated with equipment for which rapid intervention is unlikely to be needed.
- Valves with a low operating or inspection frequency (i.e. less than once every 6 months).
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Category 3 (C-3) valves
Category 3 valves are normally non-operating valves that are used or inspected in particular circumstances on an infrequent or rare basis (e.g. hot tap valves, hydrostatic test vent, high point vent or low point drain valves located in pipe rack) and are NOT used in HSSE critical activities. (SAFTENG comment – such as energy isolation/LOTO)
HFE DESIGN REQUIREMENTS FOR THE SELECTION, LOCATION, AND ORIENTATION OF VALVE OPERATORS/ACTUATORS
VALVE CRITICALITY
Category 1 valves (C-1)
PERMANENT ACCESSIBILITY shall be provided at deck or ground level or via a permanent standing elevated surface. If such access at ground or deck level is not practical, access by stairs to the elevated platform is acceptable.
Valve identification and status shall be CLEARLY VISIBLE to an approachable operator position i.e., on an adjacent walkway, access platform, or in space around equipment that is intended for human access.
Category 2 Valves (C-2)
Height and reach distance and visibility of C-2 valves should be the same as for Category 1 valves i.e., “preferred” location as outlined in (4).
Category 2 valves may be located within the “acceptable area” as outlined in (4), depending on their size and the force needed to operate them.
Where ground level access, or where deck level access by stairs, is not justifiable a vertical fixed ladder plus a small standing surface shall be provided for access to C-2 valves.
The use of auxiliary equipment to gain access (e.g. mobile platforms, man lift, or scaffolding) for maintenance purposes may be acceptable as long as it is indicated and allowed for in the design by preserving sufficient space and access for personnel, tools, parts, and equipment.
Identifying and inspecting the status of C-2 valves may require the operator to enter space not intended for human access, or to temporarily adopt an awkward posture provided doing so does not induce human error or put the operator at risk of injury or exposure to hazards.
Category 3 valves (C-3)
Permanent accessibility to and visibility of C-3 valves is desirable but not essential.
No specific location requirements are imposed.
The use of auxiliary equipment to gain access (e.g. mobile platforms, personnel lift, and/or scaffolding) to C-3 valves shall be indicated and allowed for in the design.
Portable ladders should not be used for accessing C-3 valves. Any proposed exception(s) to this shall be subject to specific review and approval.
Height and reach distances to C-3 valves when operated from auxiliary equipment shall conform to the “preferred” location as outlined in (4).
And those are only two (2) parts (my favorite parts) of the DEP. So as you can see, this is a detailed engineering document that can help us establish the criticality of our valves and our necessary access to them.
Already in 2018, we have seen valves intended for “emergency shutdown” be in locations that are NOT accessible by operators. These problems have come about through original process design/layout that was done with little thought given to process safety or in some cases there were changes made during construction that did not go through the MOC process and thus a platform was cut from the design to save $ or space and thus now we have emergency valves that are not accessible.
My suggestion for existing facilities is to use this document (or one you have established in-house) and establish your Category 1 (C-1) valves and then determine if these valves would meet the criteria laid out in this DEP. Once we have reviewed our C-1 valves, we then turn our attention to those valves we put in Category 2 (C-2) and then on to Category 3. I would even consider this be a topic of discussion/review during our PHA’s; at least those valves we consider to be Category 1 (C-1) valves. But keep in mind, the earlier we do this analysis, the easier and cheaper it will be to make desired changes to our valve types, locations, actuators, etc. If you’re in the early stages of design for a new process, then management should give much consideration to adopting an HF practice such as this or developing one of their own.
CLICK HERE to view the pdf