Primary vs secondary retention
Primary retention holds the object in place during normal operation. Secondary retention provides an additional layer of protection if the primary system fails.
This distinction is particularly important in working-at-height, offshore, oil & gas, renewable energy and industrial environments, where a falling object can present a serious risk.
| | Primary Retention | Secondary Retention |
|---|
| Purpose | Holds the object in its normal operating position | Helps prevent the object from falling if primary retention fails |
| Example | Bolts, brackets, clamps or mounting system | Retention wire, safety wire or retention net |
| Normal role | Main attachment | Additional independent protection |
| Failure scenario | Designed to prevent movement/detachment | Designed to arrest or retain the object after primary failure |
| Typical application | Equipment installation | DROPS prevention |
| Independence | Main securing method | Should provide an additional securing method where required |
Example: A light fitting at height
Consider a light fitting installed on an offshore structure.
Primary retention:
The light is attached using its specified mounting bracket and fixings.
Secondary retention:
An independent stainless-steel retention wire is connected between the light and a suitable structural attachment point.
If the mounting bracket or primary fixing fails, the secondary retention system can help prevent the light from becoming a falling object.
Why use both?
Primary retention can be affected by:
- Vibration
- Corrosion
- Fatigue
- Mechanical damage
- Loose or failed fixings
- Incorrect installation
- Environmental conditions
Secondary retention provides an additional line of defence.
It should not, however, be viewed as a replacement for correctly engineered and maintained primary fixing.
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