Fire Damage Assessment or Heat Damage from Process Upset

When the worst happens, the I2C expert fire damage assessment team can help you inspect and identify the type and extent of the damage. We get you up and running again quickly, while reducing unnecessary replacements [1].  We are ready to rapidly deploy fire damage assessment teams to locations throughout the US and abroad when you need service fast!

Using field metallographic replication, ultrasonic testing, hardness testing, visual inspection, and other techniques, our fire damage analysts will assess the type and extent of the damage to every affected component. We then provide you with guidance or a fitness-for-service determination, and a plan to help you get back up and running quickly and safely. Here’s how it works:

An introduction to fire damage assessment of industrial components: 

Typically, a customer will request our fire damage assessment, which usually includes a combination of visual inspection, portable Brinnell hardness evaluation, and field metallographic replication (FMR) of the components that have experienced fire damage. Customers should provide as much information as possible about the time, type, and nature of the fire, but often fires occur at unmanned facilities or during times when no personnel are present.

Fire damage assessment objectives include determination of the critical heat exposure zones, assessment of the condition of affected materials in the system, and repair or replacement recommendations for components, as needed. A report is provided with details of the results of inspection, evaluation, and the conclusions for repair or replacement. All told, we can help you save money by quickly returning to safe operations without replacing unncessary parts.

Fire Damage Assessment Methodology

Exposure to high-temperatures is not the only requirement for damage to occur in carbon steels and other components. In fact, steel piping, tubing, and pressure vessels are normally produced by pouring molten steel at temperatures above 2800 °F to make cast ingots. The casting process is normally followed by hot forming (e.g. hot rolling or forging) that is usually performed in the temperature range of 1800-2000 °F or above.

The next step of pipeline and pressure vessel fabrication usually includes welding, the process of depositing liquid steel on the carbon steel to bond the walls together. Welding is sometimes followed by post weld heat treatment (PWHT), involving heating at about 1150 °F or a similar specified temperature for several hours to achieve the desired strength and properties.  A carbon steel vessel involved in a fire can experience thermal cycling during the fire event and with uncontrolled heating and cooling. The steel may reach temperatures similar to PWHT in areas and similar to normalizing (the process of heating to ≥1560 °F followed by air cooling, which reduces the strength of the steel) in other areas.  Hence, the fact that steel is accidentally heated to these high temperatures does not necessarily mean that the steel is damaged.

It is on this basis that a fire damage assessment is conducted, leading to the determination of fitness for salvage for the vessel or recommendations for repair or replacement practices.

Fire Damage Assessment Procedures

The assessment procedures for evaluating pressure vessels, piping and tanks subjected to flame impingement and the radiant heat of a fire are covered by Part 11 of the API/ASME Standard on Fitness-For-Service API 579-1 / ASME FFS-13.  These fire damage assessment procedures were applied in order to define the maximum heat exposure zone of the affected areas at the Operator’s Facility. The Level 1 assessment procedure of this part of the API/ASME standard is a screening criterion where the acceptability for continued service is based on the Heat Exposure Zones and the material of construction of the components affected during the fire.

The screening criteria are conservative, and calculations are not required to establish suitability for continued service.  Components do not need a further assessment of mechanical properties if they are assigned to an acceptable Heat Exposure Zone and there is no mechanical damage or dimensional deviation. The Heat Exposure Zone levels for the materials of construction that are acceptable per a Level 1 assessment are shown in Table 1.

Table 1.  Description of Heat Exposure Zones to Evaluate Fire Damage

Heat Exposure Zone Description
I Ambient temperature during fire event, no fire exposure
II Ambient to 65oC (150oF), smoke and water exposure
III >65oC to 205oC (>150oF to 400oF), light heat exposure
IV >205oC to 425oC (>400oF to 800oF), moderate heat exposure
V >425oC to 730oC (>800oF to 1350oF), heavy heat exposure
VI >730oC (>1350oF), severe heat exposure

Note: The source for this material is API 579-1/ASME FFS-1.  Details of the damage that is likely to occur in each zone are described in this document.

Visual Inspection

Visual examination of the piping, components and surrounding areas affected by the fire is normally conducted as the first step in the assessment. Visual inspection can provide a variety of tools for estimating the fire damage or temperature exposure in different zones and is the first step to determine the severity and extent of heat damage.

Hardness testing

To determine if the fire-exposed material suffered any softening or hardening due to microstructural degradation or changes during the fire (which would indicate a need for repair or replacement), hardness is usually measured with a portable hardness tester. To determine if fire-exposed material has suffered any softening or hardening due to microstructural degradation or changes during fire or process upset (which would indicate a need for repair or replacement), hardness is usually measured with a portable hardness tester. I2C inspectors often uses a tool commercially known as a “Telebrineller” hardness tester and a MIC 20 ultrasonic contact impedence hardness tester. The Telebrineller method measures “bulk” hardness of the sample by pushing into the material and measuring the amount of denting at a given pressure. The resulting measurement includes a volume measurement incorporating the surface and a depth of 2-3 mm below the surface. Telebrineller measurements can indicate fire damage that extends beyond the surface “skin” of the metal being tested. MIC 20 provides a expedient and precise reading, areas such as heat affected zones, and other small areas are readily tested. Application of either test method much be carefully chosen based on material type and desired result. I2C’s experienced staff has the knowledge to properly apply these techniques where applicable generally in conjunction with material assessment associated with elevated temperature exposure

Recommendations for Repair, Replacement, or Other Changes

Repairs to fire-damaged structures should provide the strength, fire resistance, durability and appearance appropriate to the proposed use and projected design life of the equipment. Fire-damaged structures are often capable of being repaired rather than replaced. Inspection experts can successfully assess fire-damaged structures using a range of forensic analysis techniques and specify well-informed repair solutions. As an alternative to demolition this can provide substantial savings in capital expenditure and also savings in consequential losses, by permitting earlier reuse and reoccupation of structures.

Finally, the results of the visual inspection, hardness testing, field metallographic replication, and other inspection efforts are analyzed using API specifications. recommendations for repair, replacement, or other changes to the materials are provided. In some cases, risk-based inspection (RBI), mechanical testing, or a mechanical integrity evaluation may be needed. I2C’s extensive network of vendors provides a unique benefit to clients by which mechanical testing is often completed in less than 24 hours.

The scope of work of fire damage assessment is typically:

  • On site visit of the fire damage assessment team. We meet with the fire response team and perform a preliminary evaluation of the scope of the fire and associated damage.
  • Interviews with personnel to determine the on-site conditions before and during the fire, along with possible cause of the failure.
  • The heat exposure zones are identified based on API 579 FFS assessment guidelines. Visual inspection and NDE are often combined to complete the Level 1 FFS assessment.
  • API 579 FFS Level 2 and Level 3 assessment is performed on anything which does not pass the Level 1 FFS inspection.
  • Components may be shipped to labs or tested on-site by FMR and other means. A inspection and testing plan will be devised based on the assessment of Level 1 and Level 2 FFS.
  • Level 3 FFS is performed with our mechanical analysis and FEA partners to determine if components are safe for continued operation.