Safety in Design

2 Procedural, Active, and Passive Safety

2.1 Introduction

How the safety in the chemical industry can be improved by the application of intrinsic continuous process safeguarding was discussed in Chapter 1. The concept was compared with extrinsic process safeguarding, which starts working upon a signal. It is, for other fields in society, useful to distinguish between procedural, active, and passive safety. Their definitions are given in Section 2.2. In Section 2.3, four examples of emergency power units that failed to come into action are dealt with. Three examples concern hospitals and one example a chemical plant. An emergency power unit is an active safety measure, as it starts working upon a signal. The failure of the blowout preventer (BOP) (an active safety measure) during the Gulf Oil accident in 2010 is discussed in Section 2.4. Section 2.5 deals with the safeguarding of Formula One races by means of mainly passive safety measures. Finally, Section 2.6 discusses explosion panels, also called bursting disks. These parts are designed to give in, if, due to a dust explosion, the subsequent pressure in a piece of equipment surpasses a predetermined value. Safeguarding by these components is continuously present.

2.2 Definitions

The definitions in this paragraph are borrowed from Kletz’ and Amyotte’s book [1]. A procedural safety method is a method activated by a human. The extinction of a fire by a fireman is an example. Of course, to avoid fires, preventive ...