Fire protection comes in two generic forms, active or passive.
Active fire protection systems are systems that require some form of intervention or activation before they can work. Examples of active fire protection include deluge or sprinkler systems, halon or CO2 suppression systems and fire dampers closed by actuators. Such systems generally require routine maintenance and testing to ensure that they will work when required.
Passive fire protection (PFP) systems are systems that by a process of heat absorption and/or thermal insulation reduce the rate of temperature rise of the item being protected. They require no intervention to work and if designed and chosen well will require little or no maintenance for the life of the installation.
The term ‘passive fire protection’ (PFP) refers to any fire protection measures which do not require manual or automatic actuation for them to function to their design intent.
Common types of Passive Fire Protection
- Fiber boards
- Calcium silicate boards
- Spray fibers
- Composites (e.g. plastics and phenolic)
- Lightweight cementitious
- Thin film intumescent (solvent/water-borne)
- Thick film intumescent (epoxy)
The fire performance function of the above PFP materials and others vary when exposed to fire and while considering the right PFP for the job, several factors need to be taken into consideration. These include strength, durability, operating environment, weight, system integrity, corrosion performance, health and safety impacts, ease of installation, cost effectiveness and fire scenario
The most common form of passive fire protection used in modern, high-risk industries such as oil, gas and petrochemical facilities are epoxy intumescent coatings. As the oil & gas market involves activities ranging from exploration, production, storage and transportation of highly flammable liquids and gases, intumescent PFP is suitable in protecting structural steel from extreme heat caused by hydrocarbon fires
These are coatings that (as well as providing full corrosion protection for the life of the installation) in the event of a fire react to heat by swelling in a controlled manner to many times their original thickness to produce a carbonaceous char, which acts as an insulating layer to protect the steel substrate.
They are normally spray or trowel applied in the form of a two-pack epoxy coating material that is applied directly onto a clean, prepared steel surface. Once cured the system is ridged and bonded on place. The system is typically reinforced with a mesh (steel or glass/carbon fibre) at mid thickness depending on fire type and protection requirements.
Typically thickness of intumescent epoxy PFP will range from 3 to 20 mm. The system will have a very long life, maintenance free, provide excellent corrosion resistance and be capable of taking heavy mechanical knocks.
Hazards, risks and safety critical elements
The requirement for fire protection is normally driven by a process of identifying hazards such as impact damage or corrosion resulting in a release of fuel (oil, gas, LNG, etc.) that may cause thermal shock, explosions and fires of various ferocity such jet fires and pool fires.
From these hazards it is possible to identify specific risks such as escalation of the incident, structural collapse, blocked escape routes and resultant loss of life or assets.
This leads to the identification of Safety Critical Elements; these typically include items such as primary structural steel, divisions (bulkheads and decks), pipes and vessels plus their supporting structures and items such as ESD valves and actuators. It is these safety critical elements that may require fire protection.
Why is fire protection critical?
Fire protection is a legal requirement in most countries.
The fundamental purpose of fire protection systems is to:
- Prevent the passage and spread of smoke and fire from one area of a building to another
- Allow for the safe escape of the building occupants
- Prevent/reduce damage to the building structure and neighboring structures, and reduce the risk of collapse for the emergency services
In essence, it is about people protection and asset protection.
It is important to provide protection to ensure the item being protected is capable of fulfilling its function until the incident is brought under control or the installation is evacuated.
Typically, protection is applied for the following reasons:
- Decks and bulkheads/firewalls: To prevent the passage of heat and smoke, and to provide insulation and personnel protection.
- Structural steelwork: To prevent structural collapse, fracture and escalation due to jet fires.
- Vessel and pipe supports: To prevent structural collapse.
- Vessels: To prevent inventory temperature and pressure rising (which could result in an explosion).
- Pipework protection: To prevent fracture and escalation due to jet fires.
- ESD valves and actuators: To ensure shutdown containment and prevent escalation.