Fireproofing piping supports — specifically the application of Passive Fire Protection (PFP)— is a critical mitigation strategy designed to prevent the structural collapse of pipe racks during a flammable liquid fire. In most state fire codes and the IFC, flammable liquid piping supports inside a secondary containment are REQUIRED to be protected from the effects of a pool fire.
5703.6.8 Piping supports.
Piping systems shall be substantially supported and protected against physical damage and excessive stresses arising from settlement, vibration, expansion, contraction or exposure to fire. The supports shall be protected against exposure to fire by one of the following:
1) Draining liquid away from the piping system at a minimum slope of not less than 1 percent.
2) Providing protection with a fire-resistance rating of not less than 2 hours.
3) Other approved methods.
Because unprotected structural steel loses roughly 50% of its load-bearing capacity when temperatures reach approximately 1,000°F (538°C), a support failure during an incident would cause the piping to rupture. This releases additional hazardous or flammable inventory into the fire, leading to a catastrophic escalation or “domino effect”.
The primary industry guideline for determining where and how to fireproof these supports is API 2218 (Fireproofing Practices in Petroleum and Petrochemical Processing Plants)**. The standard utilizes a risk-based approach to define a “Fire Scenario Envelope” around equipment containing significant flammable inventories.
- Pool Fires: Historically, API 2218 focused primarily on liquid pool fires, using inventory calculations to define a typical 6 to 12-meter exposure radius where structural supports require PFP.
- Jet Fires: Pressurized gas releases create highly erosive, directional jet fires that can quickly compromise traditional fireproofing. Following industry incidents, API 2218 incorporated annexes for assessing jet fire scenarios, which may dictate larger fireproofing radii, specialized PFP materials, or active mitigation like emergency depressuring systems.
Primary PFP Materials for Piping Supports
Selecting the right PFP involves balancing the required fire rating duration (typically tested against the UL 1709 rapid-rise fire curve), weight limitations, and environmental durability.
Dense Concrete: The traditional standard. It is highly durable against pool fires and mechanical impact, but it adds massive dead weight to the structural steel. If the concrete cracks, water ingress creates a severe risk of Corrosion Under Fireproofing (CUF).
Intumescent Epoxies: These 100% solids, two-component coatings are applied like thick paint and swell to form an insulating char layer when exposed to extreme heat. They are lightweight, resist moisture (significantly reducing CUF risk), and are effective against both pool and jet fires, though they require strict quality assurance during application.
Lightweight Cementitious (LWC): Cheaper and lighter than dense concrete, LWC is often sprayed onto supports. However, it is more susceptible to mechanical damage, elastic flexure, and weathering, which can compromise the bond to the substrate.
Flexible Blankets: Pre-formed, modular covers used primarily for valves, actuators, and specific nodes that require regular maintenance. They allow operators to access equipment without destroying the PFP.
Overview of API 2218 Fireproofing Practices
This podcast episode explores the specific fireproofing materials, application techniques, and risk mitigation strategies outlined in the API 2218 standard.