PetroStreet

What are the practices to investigate pressure relief device activation?
This is to identify if there has been any actual overpressure demand or a failure of the device?

API 585 is the right reference when deciding about an event related to a pressure equipment integrity concern.
Once determined that there has been a failure of pressure relief device resulting in a loss of product or an actual overpressure scenario, guidelines provided in API 585 can be applied. As I can see Level-2 investigation is recommended in case there is a failure of relief device resulting in release of product.

Yeah, API 754 in some examples asks /recommends having investigation on the event however there has not been clear specific case to case recommendations.
And there I am trying to understand that do all Tier-3 events should be investigated?
API 585 is clear but that focuses on the integrity part (premature lifting) but the actual activation of PRD.

Correct that is jeem.
Yes, API 585 focuses on the part of the failure actually occurred on the pressure equipment and its investigation.
Surge in pressure means an actual demand, what triggered that should be investigated in all cases. We do not have a controlled practice at our place to do so but having an actual LOPC as a result of that triggers an investigation.
In my opinion, all cases of an actual demand for PSV should be investigated.