API 579 Part 11 Fire Damage Assessment Screening

API 579 Part 11 Fire Damage Assessment is used when pressure equipment has been exposed to fire, flame impingement, or overheating and the site needs a defensible restart decision. Fire exposure can affect geometry and material properties, so integrity decisions should be based on the exposure scenario and inspection findings—not visual appearance alone.

Use this screening workflow to confirm Part 11 applicability and whether your available information is sufficient to support a defensible evaluation. In many cases, a formal Part 11 assessment is needed to determine whether the equipment can safely return to service as-is, requires operating restrictions or rerating, or requires repair/replacement before restart.

Use the screening questions below to determine whether a formal Part 11 evaluation is recommended.

API 579 Part 11 — Fire Damage Assessment Screening (Workflow)

Instruction: Answer all questions (use N/A if truly not applicable), then click “Check if FFS is needed”.

1) Has the equipment experienced a fire exposure event or overheating due to a process upset that could have affected the pressure boundary?
For example; a hydrocarbon pool fire exposes a vessel skirt and lower shell, or an internal reaction/process upset overheats a process vessel for a short duration.
2) Is the item being screened a pressure boundary component covered by Part 11 (pressure vessel pressure boundary, piping pressure boundary, or storage tank shell course/nozzle neck pressure boundary)?
For example; vessel shell course and nozzles, piping circuit segments and fittings, or tank shell course plates and nozzle necks exposed to a fire.
3) Is the concern primarily about items not specifically addressed by Part 11 (e.g., tank roof/bottom, structural steel platforms/ladders, instrumentation/wiring, insulation/paint as “items” themselves)?
For example; roof/bottom plate questions are typically handled under tank inspection practices, while Part 11 focuses on the pressure boundary; structural distortion alone does not automatically mean the pressure envelope is unfit.
4) Do you need a documented evaluation to determine whether the equipment is acceptable for continued operation following the exposure?
For example; the unit is preparing for restart and management requires a documented basis for return-to-service, rerate, repair, or retirement.
5) Has “fire damage evidence” been preserved and documented (photos, sketches, exposure footprint, nearby damage indicators, insulation/fireproofing condition, shrouding/orientation effects)?
For example; photos show insulation removed in limited areas, one side shielded by an adjacent exchanger, and clear boundaries of discoloration/scale.
6) Have key operating/event data been retrieved promptly (pressure/temperature trends, relief activity if any, and other recorded process information before/during the incident where available)?
For example; DCS historians often retain data for limited time—retrieve the vessel/piping pressures and temperatures during the event as soon as possible.
7) Has firefighting/mitigation information been documented (water monitor/hoses location, flow directions, and the type of water used), recognizing quench effects can matter?
For example; records show continuous water spray on one side of the shell while the opposite side saw radiant heat without active cooling.
8) Have Heat Exposure Zone(s) been defined for each exposed vessel/tank/piping circuit to decide what requires assessment?
For example; the lower shell course is assigned a higher zone than the upper shell due to stronger temperature indicators; insulation/fireproofing reduced the zone in protected areas.
9) Are temperature indicators/observations sufficient to categorize the component(s) into appropriate Heat Exposure Zones (including using multiple indicators and damage clues)?
For example; coating discoloration, scale formation/thickness, melting/distortion of nearby non-metals/low-melting metals, and other field indicators help bound the exposure temperature range.
10) If multiple fire severities affected the same component, will the highest Heat Exposure Zone be used for assessment (unless clearly justified to treat portions separately)?
For example; one nozzle area shows stronger indicators than the shell—use the more severe zone unless there is a distinct reason and clear boundary to separate assessments.
11) If the information is insufficient to confidently assign a Heat Exposure Zone, will the component be assigned to the next more severe zone (conservative assignment)?
For example; limited access prevented confirmation—treat the component as a higher zone until better evidence is obtained.
12) Is any affected pressure boundary believed to be in a higher severity Heat Exposure Zone (typically Zones V or VI), or is flame impingement suspected?
For example; heavy oxidation/scale, melting of nearby non-metals, or strong indicators suggesting severe heat exposure near the fire source.
13) Is there evidence or suspicion of mechanical distortion/structural damage (bulging, dents, out-of-roundness, out-of-plumb, sagging, warped supports)?
For example; a vertical vessel shows a measurable bulge in the shell course, or a horizontal drum shows localized out-of-roundness after the event.
14) Is there evidence or suspicion of crack-like flaws in the pressure boundary (including at welds/nozzles) that would require targeted NDE?
For example; visual hot-spot cracking at a nozzle reinforcement toe, or concern for cracking in highly heated regions requiring MT/PT/UT as appropriate.
15) Is there evidence or suspicion of thickness loss (general/local thinning, localized hot spots, oxidation-related metal loss) requiring UT thickness mapping/profiles?
For example; exposed shell shows scale/oxidation and UT indicates reduced thickness near the flame footprint compared to unaffected areas.
16) Is there concern for degradation of mechanical properties or microstructure (strength/ductility/toughness), such that hardness testing and/or metallography may be needed?
For example; a heat-treated alloy or carbon steel area shows strong heat indicators; strength and toughness changes must be considered beyond what’s visible.
17) Is there concern that corrosion resistance/environmental cracking susceptibility may have changed (especially for alloys that can be sensitized/softened), requiring this to be addressed before return to service?
For example; stainless components exposed to high heat may have altered corrosion resistance; even if “structurally acceptable,” environment cracking risk must be considered.
18) Have post-fire inspections been performed to identify and document fire-related damage mechanisms and the affected footprint?
For example; visual exam plus UT thickness in exposed regions and targeted NDE at welds/nozzles near the heat-affected boundary.
19) If distortion is suspected, has shell dimensional profiling been performed (manual profiling or laser scan/mapping where needed)?
For example; a vertical vessel profile is taken using a reference vertical line and measured bulges/dents at increments; complex cases use laser scanning.
20) Are the required geometry/thickness/material inputs available for the affected region(s) (dimensions, measured thicknesses, material grade, weld/PWHT condition where known)?
For example; provide nominal and minimum measured thickness, diameter, nozzle sizes, and confirmed material specification for the exposed course/spool.
21) Have appropriate additional NDE methods been selected based on the suspected deterioration mode (e.g., MT/PT/UT as needed)?
For example; MT/PT at highly stressed weld toes and UT for subsurface indications or thickness mapping where thinning is suspected.
22) For mechanical/jointed items in higher exposure zones (as applicable), have leak testing and joint integrity checks been addressed prior to return to service?
For example; consider leak testing for flanged joints, non-seal-welded threaded joints, valves, packing/gaskets, and heat exchanger tube sheet rolled joints.
23) Have “consumable/softening-prone” items been addressed (gaskets/packing replaced, bolting/fasteners evaluated for softening where applicable, ancillary small piping/tubing assessed for replacement where justified by exposure severity)?
For example; replace all gaskets/packing in the affected area and evaluate/replace flange stud bolts (e.g., B7) if high heat exposure is suspected.
24) Does visual inspection confirm there is no mechanical damage and no dimensional deviation (i.e., no bulging/out-of-roundness/out-of-plumb/sagging) in the pressure boundary?
For example; no measured shell bulges, no nozzle deformation, and no piping misalignment attributable to the event.
25) Based on Heat Exposure Zone and material of construction, does the component appear to satisfy Level 1 screening (and therefore not require further assessment of mechanical properties), provided there is no mechanical damage/dimensional deviation?
For example; the documented temperature indicators bound the exposure to a lower zone acceptable for the material, with no distortion noted.
26) If Level 1 is satisfied, have “startup checklist” items been planned (e.g., gasket inspections/leak checks, coating repairs needed for corrosion protection before startup)?
For example; flange joints are leak-checked after heat exposure and damaged protective coatings are repaired before restart.
27) If Level 1 is not satisfied (higher zone, or distortion noted), are you prepared to proceed to Level 2 (material strength evaluation and rerating; plus flaw/distortion evaluations as applicable)?
For example; components in higher heat zones or with measured bulges typically move into Level 2 evaluation methods.
28) For carbon steel / low alloy steel / stainless steel components where strength degradation is suspected, has field hardness testing been performed (or planned) to estimate current strength?
For example; hardness readings are taken and later used to estimate tensile strength; a grid pattern helps define the heated/tempered areas.
29) Has hardness testing been planned with good practice controls (surface prep, multiple readings per location, and separating base metal/HAZ/weld where applicable)?
For example; take at least five readings per location; if weld/HAZ/base metal are present, take readings in each zone and record locations for traceability.
30) If toughness degradation is a concern (hardness changes alone are not enough), has field metallography / replica work (and/or mechanical testing of samples) been considered per Annex 11B?
For example; replication requires removing oxide/affected surface layer, polishing/etching, producing replicas, and documenting observations; toughness concerns may require additional methods beyond hardness.
31) If sample removal is being considered for lab analysis/mechanical testing, have practicality and repair implications been considered (weld repair feasibility, heat treatment needs, and sample tracking/documentation)?
For example; removal enables through-thickness metallography and tensile/impact testing, but the sample location must be documented and a repair plan must be feasible.
32) After inspection, is the controlling condition actually a different damage mechanism that must be evaluated under another Part (thinning, pitting, hydrogen damage, distortion, crack-like flaws, dents/gouges, laminations, or creep considerations)?
For example; a bulge drives evaluation under Part 8, a crack-like indication under Part 9, local thinning under Part 5, etc.
33) If the equipment is not suitable at design conditions, is the intended path defined: rerate limits, repair/replace affected sections, or retire from service?
For example; establish a reduced MAWP (or tank max fill height), adjust temperature limits, or proceed to repair/replacement based on findings.
34) Have the Heat Exposure Zone assignments, inspection results, and evaluation basis been documented for record retention in the inspection files?
For example; retain photos, the HEZ map, dimensional profiles/laser scan outputs, NDE reports, hardness/metallography logs, and the final acceptability decision.
Answer all questions, then click “Check if FFS is needed”.

When to Use API 579 Part 11

API 579 Part 11 is typically used when the controlling concern is fire or overheating exposure and the decision requires a structured engineering basis. Common triggers include:

  • Fire exposure involving flame impingement, pool fire, jet fire, or localized equipment fires affecting pressure boundaries
  • Evidence of overheating effects such as distortion, local bulging, or suspected property degradation
  • A need for a restart decision based on defined criteria and inspection results
  • Cases where inspection must confirm thickness, geometry, and potential material property impacts in the affected region
  • A need to define practical integrity actions—repair now, replace affected components, rerate/limit operation, or monitor with defined requirements

If the controlling condition after inspection is primarily metal loss, distortion, cracking, or creep, the evaluation may also require routing to the applicable API 579 Part (for example, Parts 4/5, Part 8, Part 9, or Part 10) to address the controlling mechanism.

What to Gather if Screening Indicates FFS Is Needed

If this workflow indicates that a formal API 579 Part 11 assessment is recommended, prepare the following to support a defensible evaluation:

  • Fire event summary (location, exposure type, affected areas, and duration if known)
  • Photos and现场 observations identifying the heat-affected region and boundary of concern
  • Inspection/NDE results in the affected region (thickness readings, dimensional checks, MT/PT/UT as applicable)
  • Any hardness checks or metallurgical evaluations performed (if available)
  • Equipment/component details (geometry, thickness, materials, and drawings if available)
  • Operating basis for restart decisions (pressure, temperature, and any required restrictions)

Request an API 579 Part 11 Fire Damage Assessment

If this workflow indicates that an API 579 Part 11 Fire Damage Fitness-for-Service (FFS) assessment is needed, the next step is a decision-ready engineering evaluation using your incident information, inspection findings, and operating basis.

Inspection 4 Industry LLC (I4I) performs API 579-1 / ASME FFS-1 Part 11 assessments of existing equipment for fire damage and delivers a complete report stating fit-for-service or not fit-for-service, any required operating restrictions or rerated limits, and practical integrity actions—repair now, repair at turnaround, replace affected components when required, or return to service with defined monitoring.

To proceed, send your fire event summary, photos, inspection/NDE results, and equipment operating basis and request an API 579 Part 11 Fire Damage Assessment (FFS).

 

Free newsletter!

Sign up to receive my monthly newsletter covering all the latest courses and updates.

 

New! Comments

Have your say about what you just read! Leave me a comment in the box below.