Human Factors Engineering In The Chemical Process Industry

Something new and interesting came up recently while I was checking some documents. This was related to "Human Factors Engineering" (HFE) related to an upstream oil & gas engineering installation. Today's blog entry is a kind of primer on HFE in context to the chemical process industry.

Let us start with the general definition of HFE:

HFE is a multidisciplinary field that considers the integrated knowledge of human capabilities, limitations and needs in the interaction between humans, technology and the working environment.

HFE is applied to the design of work systems, workplaces and products, with the following objectives:

1. To increase the operational performance, safety, health and comfort of the work system (through attention to safety, operability, maintainability and constructability in design).

2. To reduce the likelihood of or prevent human errors and/or limit the consequences (through attention to human and systems reliability in design).

3. To enhance the productivity of human efforts (through attention to efficiency in design)

4. To enhance overall system performance by improving the ease and efficiency of use (through attention to usability issues in design)

5. To incorporate user knowledge in the design of the system / product (through attention to user acceptability and marketability).

Some guidelines related to human factors and ergonomic requirements in a chemical process plant are provided below:

Access Requirements in a Chemical Process Plant:

All work areas shall be designed to provide safe and efficient access and egress for operations, maintenance and inspection activities under all conditions.

Design is required to allow for safe access at all times to all areas, particularly those at height (2m and above) to enable easy access of valves and equipment during operations, maintenance, inspection and testing.

Provision of platforms for easy access to frequently serviced items is required. Instrument check or sampling points for example shall be positioned to enable operation and maintenance access from permanent walkways and platforms. The design of vessels / equipment shall accommodate easy platform access for external and internal inspection, isolation from the process, safe venting, purging and draining.

Within plant areas the preference for platform access for frequently used access points is for stairways rather than ladders. Installation of ladders as a means of access shall be minimized.

Two means of access shall be provided at any platform above grade, when the lack of such means might prevent the escape of a person in the event of an emergency.

Escape stairways, ladders and platform balustrade / handrails are to be painted for easy identification. The leading edge of steps on all platform staircases shall be coated with industrial grade anti-slip material suitably colored (e.g. yellow) for clear visibility. Ladders must be coated with industrial grade anti-slip material all over.

Platform ladders are to be caged and installed at 90° angles so access and egress is by a sideways step. Descent shall never be by a backward step onto ladders.

Specific access guidelines are there for mechanical equipment such as piping, valves, equipment (filters/strainers, vessels, columns, heat exchangers, pumps) and for electrical and instrumentation which cannot be covered in this blog entry and readers are advised to research the subject further.

Space & Layout Requirements in a Chemical Process Plant:

During the location, orientation and development of each site layout, the design shall ensure that access, space and laydown areas shall allow for efficient operation / maintenance. The layout design shall address component replacement routes to the main equipment.

There shall be sufficient space around compressors, valves, control panels, instruments and other machinery parts, including flanges, to allow the use of tools of the correct dimensions required for the specific part.

Adequate means of handling, storage / laydown areas and space management including means of access shall be incorporated within the design to ensure that lifting and handling operations will be performed in a safe and effective manner.

Where hoists, cranes, fork-lifts and other lifting equipment may be required to move plant items, sufficient spatial volume shall be allowed around the machinery for the lifting equipment to be positioned and operated correctly and safely. Sufficient space shall also be allowed for any transport required for the removal of the equipment to the workshop/stores etc.

The design shall eliminate the requirement for manual handling of loads, materials and equipment during operations and maintenance where possible.

Equipment layout shall ensure the following:

- All activities required to maintain and operate the equipment should be performed by personnel wearing proper clothing, personal protective equipment, and using the proper tools.

- Access is not blocked by panels or structural members.

- All adjustment points and test points are accessible.

- All displays are readable.

- Sufficient space is provided to operate and maintain the equipment.

Positional Requirements in a Chemical Process Plant:

Plant items and equipment which require regular/frequent attention shall be positioned at optimum height and reach for the user (operations, maintenance, inspection and test etc.).

Manually operated valves shall be positioned at optimum height and reach for operation and maintenance.
Instrument displays, gauge glasses and viewing ports shall be located, wherever possible, at eye level for the user, while at the normal viewing position.

Instruments shall be positioned at suitable height and reach for ease of maintenance and calibration, without compromising operational requirements.

Sampling positions shall be set at ground level, wherever possible, and at the optimal height for the operator (normally between elbow and shoulder level).

Lubrication and seal buffer systems shall not obscure the space required for operation, maintenance, inspection, testing etc. of other plant items. Greasing points shall be easily accessible from platforms / fixed ladders.

The above is a general overview of what HFE is all about. I would be happy to know the opinion of the members of the "Cheresources" community.

Regards,
Ankur.