It also deals with the barriers intended to prevent accidents and to reduce the consequences of any incidents which nevertheless occur. Fire and explosions attract particular attention.
Technical safety is a key concept, which relates to the robustness of a process plant against hazards and accidents.
In this context a process plant is a system consisting of a number of components intended to deal with a hydrocarbon stream from a reservoir, pipeline or ship.
The output of such a plant is processed hydrocarbons. Offshore installations carry out a simpler form of processing in order to optimise hydrocarbon transport by pipeline or ship.
On land, the products are further processed – to export-quality gas, for instance, or to petrol for sale from service stations.
Key HSE challenges include preventing and controlling hydrocarbon leaks, explosions, fires, chemical reactions, discharges or emissions of toxic/corrosive substances, and human safety.
Design, operation and maintenance
To ensure that process equipment always meets requirements, strict standards are set for the way those in charge of a plant must handle its design, installation, operation and maintenance. Unfortunate solutions, lack of expertise and inadequate or inaccurate maintenance are often identified as underlying causes of undesirable incidents.
The design and construction of a process plant are crucial for its HSE level during operation, because these are the stages when technical safety gets built in. An example of an incident where design errors were the direct cause was provided by the gas leak on the Visund field in the North Sea on 19 January 2006.
Major accident risk – hydrocarbon leaks
Hydrocarbon leaks account for a substantial proportion of the total risk of major accidents both offshore and at land-based plants.
A major accident is defined as an acute incident, such as a major discharge/emission or a fire/explosion, which causes several serious injuries and/or loss of human life, serious harm to the environment and/or loss of substantial material assets.
A process plant will contain a number of measures or barriers intended to reduce the probability of a major accident occurring. These barriers are also intended to limit the consequences of any incident which nevertheless takes place.
Hydrocarbon leaks, particularly escapes of gas under pressure, normally pose the biggest risk of fire. The most important barriers against such leaks are a plant designed and built to the right specifications. It must also be operated in such a way that the built-in robustness is maintained throughout its economic life.
Inspecting potential leak points represents a key barrier in the operations phase. Safety systems such as gas detectors are also important in dealing with escapes by providing rapid identification and automatic countermeasures.
The latter can include shutting down production, disconnecting potential ignition sources and possible pressure bleed-off to reduce the volume available for combustion.
A total of 251 leaks bigger than 0.1 kilograms per second were identified in 1996-2003. None of them ignited, demonstrating the effectiveness of the barriers installed to prevent explosions.
The industry devotes substantial resources to preventing fires and explosions. Learning from incidents and viewing them in an international perspective are important in this context.
A case in point is the disaster at BP’s refinery in Texas on 23 March 2005, when 15 people were killed and roughly 170 injured in an explosive fire caused by leaking hydrocarbons.
The subsequent investigation criticised a safety culture more concerned with the “right” behaviour and good incident statistics than process safety and the risk of major accidents.
The PSA has regulatory responsibility for a number of land-based process plants, where activities differ from work on offshore installations. That applies particularly to development phases, when traditional construction methods prevail.
In the operations phase, the biggest contributor to risk at the land-based plants will be a hydrocarbon leak with consequent fire and explosion.
The process at some of these facilities is more complex than on offshore installations, and can be based on a very different operations philosophy.
On the seabed
Processing equipment is increasingly being placed on the seabed. Such subsea solutions offer both safety benefits and new challenges.
Personnel are no longer exposed in the same way as before during normal operation. On the other hand, leaks in several hundred metres of water will be difficult to detect. Inspection and maintenance may also be a challenge.