How should design changes and modifications be managed?

All parties associated with the life cycle of plant and structures must provide information so plant and structures are built and used safely, including:

• identifying any hazard that could not be designed out
• advising how to construct, install, operate, maintain, cleaning, transport, dispose of the plant without risk to workers.

Information must be updated whenever:

• new information on aspects of the life cycle becomes available
• a change is made relative to the original design
• design assumptions or design conditions change.

The information needs to be understood by:

• those in control of the design process and the workplace
• workers who will use the plant and structures.

Designs can be changed or modified at any stage in the life cycle.

Depending on the stage at which the change is made, the knock-on effect of managing the change may be more complex and require greater effort to ensure risk is mitigated. Some scenarios are described below.

• Changes made during the conceptual phase are part of the natural process. The detailed design phase only starts once all concepts are approved and checked from safety and economic perspectives.
• During detailed design, change is sometimes required due to the late discovery of impractical construction of for cost reasons. It is important that, despite the change, the final design still complies with the original rationale or is deemed to satisfy rules. The final design communicated to the next party must be safe for use and not contain any unsafe aspects.
• The modifications of existing plant can only happen once the effect of the design changes on the original design and stage of life are assessed.

For example, overhead travelling cranes experience fatigue from dynamic loading and have a defined fatigue life. Changes made to the loading frequency or runways of an existing crane that differ from its original design intent constitute a design change and need to be carefully considered.

The key aspects of change management and modifications include:

• knowledge of the original design intent
• clear communication between all parties at all stages of the life cycle
• quality control during all phases to ensure any change or modification is managed.

Any changes to plant or structures made must be clearly identifiable in all records kept for operating and maintenance purposes.

Below is the list of links that you may find useful.