Module 06 · Inspection & Maintenance
Burner Maintenance
Inspection, cleaning, and return-to-service procedures for fired heater burners — covering both in-service single-burner work and full offline maintenance. Includes hot-work requirements and restrictions for work conducted with the heater online.
When Burner Maintenance Is Required
Burner performance degrades through fouling, erosion, and mechanical wear. The symptoms below indicate maintenance is needed; act before the condition impacts heater duty or safety system functionality.
Symptom → Probable Cause → Required Action
| Observed Symptom | Probable Cause | Urgency | Action |
|---|---|---|---|
| Yellow, luminous, or sooty flame | Blocked/partially blocked tip orifice; carbon buildup | Monitor / 24 hr | Schedule tip cleaning at next burner pull opportunity |
| Flame impingement on refractory or tubes | Tip misalignment; orifice erosion; air register malposition | Immediate | Take burner offline; investigate before return to service |
| Burner noise — hissing, rumbling, or popping | Partially blocked orifice; unstable air/fuel ratio; pilot instability | Same shift | Check pilot stability; adjust air register; inspect if persists |
| Individual burner flame extinguishes repeatedly | Pilot tip fouling; electrode gap excessive; low pilot gas pressure | Same shift | Inspect and clean pilot; verify ignitor electrode gap |
| Elevated CO at stack; poor combustion efficiency | Uneven air distribution; multiple fouled tips | 48 hr | Full burner audit; prioritise cleaning at next outage |
| Air register will not move / stiff movement | Lack of lubrication; thermal distortion; debris ingress | Planned | Lubricate register pivot; investigate if seized |
| Uneven heat distribution across passes | Burner-to-burner flow imbalance; selective tip plugging | 48 hr | Check individual fuel pressures; identify plugged burner(s) |
Maintenance Modes
Burner maintenance falls into two categories depending on whether the heater remains online. This distinction drives the entire risk profile and permitting requirements.
Mode A · In-Service
Single Burner Pulled — Heater Online
- One burner isolated and removed; remaining burners carry load
- Heater remains at reduced duty throughout
- Hot-work permit mandatory — adjacent burners are firing
- Maximum one burner out at any time
- Load reduction typically required before pulling burner
- High-risk environment — restricted to trained, experienced maintenance personnel
- Two-person minimum at all times; continuous control room communication
Mode B · Offline
All Burners Out — Heater Shutdown
- Heater shut down, purged, and cooled before any access
- All fuel sources isolated per the isolation procedure
- Allows full access: all burners, registers, and front plates simultaneously
- Full tip dimensional inspection possible; quarl condition survey
- Lower acute risk, but residue, hot surfaces, and confined-space hazards apply
- Preferred mode for all corrective and planned maintenance work
- See Isolation Procedure for full energy isolation sequence
Hot-Work
Single Burner Maintenance — Heater In Service
Active Firebox — Extreme Hazard
Adjacent burners are firing throughout this procedure. Flash fire, severe burns, and toxic gas exposure are credible hazards. Do not begin without a valid hot-work permit and explicit authorisation from the area operations supervisor. Personnel must not be at the burner front without a standby person present.
Preconditions — All Must Be Satisfied Before Work Begins
- 1Hot-work permit issued and signed by Operations Supervisor and Safety Officer — time window confirmed
- 2Heater load reduced sufficiently to remove one burner safely — confirmed with control room operator
- 3Gas detector check at burner front — LEL reading confirmed zero before accessing burner area
- 4Adjacent burner flames confirmed stable — no flickering or partial loss observed via peephole
- 5PPE confirmed: full-face shield (not safety glasses), heat-resistant gloves, flame-retardant clothing
- 6Portable fire extinguisher positioned at burner front, serviced and in date, immediately accessible
- 7Two-person minimum on site: one executing, one standby with clear line of sight and communication
- 8Communication established with control room — operator is in enhanced monitoring mode for COT and furnace draft throughout
Furnace Pressure — Immediate Withdrawal Trigger
Any positive furnace pressure (draft reversal) must cause immediate withdrawal from the burner front. Do not resume work until negative draft is re-confirmed and the cause investigated. A positive draft condition can blow hot gases and flame back through the open burner access.
Single Burner Isolation & Removal — In-Service
01
Obtain hot-work permit — all preconditions verified
Do not proceed until the permit is in hand, signed, and the valid time window confirmed. Verify area gas readings are zero LEL at the burner front.
02
Notify control room — confirm load reduction accepted
State which burner is being taken offline. Operator confirms COT and pass temperatures are within acceptable range to proceed at reduced firing rate.
03
Close burner fuel gas manual block valve
Close the individual burner block valve — not the header valve. Confirm valve is fully closed. Flame must extinguish; do not proceed if flame persists after
30 seconds. A persisting flame indicates a valve passing — abort and investigate.
04
Confirm flame extinguished via observation port
View through the nearest peephole. No residual flame should be visible at the tip or quarl. If flame persists, abort — do not open the burner front plate with fuel still present.
05
Close pilot gas supply valve — confirm pilot out
Isolate the pilot fuel supply for this burner. Confirm pilot extinguished via observation port or UV/IR detector panel indication. Both main flame and pilot must be confirmed out before proceeding.
06
Apply LOTO to main fuel and pilot supply valves
Each worker applies their own personal lock and tag to both valves. Tag includes: worker name, date, work description. Do not rely on verbal isolation alone in an active firebox environment.
07
Allow tip to cool — minimum 15 minutes
Use a non-contact thermometer if available. Tip surface should reach below
60 °C before handling. Insulated gloves are mandatory regardless of reading.
08
Check furnace draft at burner quarl before opening
Before opening the burner front plate, verify negative draft at the quarl opening. Use a smoke pencil or tissue: inward movement confirms negative pressure. Positive pressure = abort immediately and withdraw. Do not open the burner front under positive draft conditions.
09
Open burner front plate / tile — remove tip assembly
Use OEM-recommended tools. Keep face clear of the opening on first break of the seal. Thermal radiation from adjacent firing burners is significant — maintain face shield at all times. Do not lever or over-torque during removal; damaged threads leave the burner unserviceable.
10
Notify control room — burner out, monitoring continues
Confirm to the operator that the burner is removed and maintenance is in progress. Operator maintains enhanced watch on COT, arch temperature, and O₂ throughout. All work must complete within the permit time window.
Inspect the Quarl While the Burner Is Out
The refractory quarl (burner tile) may remain hot enough to cause burns well after flame extinction. Use this access opportunity to note any cracking, spalling, or erosion — record for repair scheduling at the next planned offline period. Quarl degradation affects flame shape and tip alignment.
Burner Tip Inspection
Inspection depth varies with the access opportunity available. The three levels below define what can be assessed in-service, during a planned burner pull, and at major overhaul.
Visual
Level 1 — In-Service Visual (via peephole, no burner pull required)
Daily operator rounds · Requires observation port access
- Flame colour: clear blue-rooted (good) / yellow luminous (fouling or excess fuel) / smoking (severely fouled or wet fuel gas)
- Flame shape: symmetric and stable / lifting off tip / coning toward or away from quarl centreline
- Flame impingement: any contact with refractory tile, wall, or visible tube sections
- Pilot flame: visible, stable blue, not lifting away from pilot tip
Pulled
Level 2 — Physical Inspection (tip removed, in-service pull or offline)
On condition / every turnaround as minimum
- Carbon deposits: Hard carbon in orifices; soft coke on external surfaces. Note which orifices are partially or fully blocked and record counts.
- Tip erosion: Orifice diameter enlarged, elongated, or undercut. Measure with pin gauges or calibrated drill bits.
- Orifice misalignment: Check swirl vanes (if present) for distortion; verify tip centreline against quarl axis.
- Material condition: Surface cracking (thermal fatigue), corrosion pitting, weld failures on fabricated tips.
- Thread condition: Tip-to-spud thread engagement; signs of galling, cross-threading, or stretched threads.
Overhaul
Level 3 — Full Dimensional Survey (all burners, heater offline)
Turnaround · All burners pulled and benched
- Orifice diameter measurement (all orifices on all tips) versus OEM as-built drawing
- Spud condition and tip penetration depth into quarl
- Burner tile (quarl) geometry: cracking, erosion, fusion damage, centreline deviation
- Air register: blade condition for warping; pivot pin wear; shutoff sealing integrity
- Diffuser/distributor condition on pre-mix style burners
- Full pilot assembly survey: electrode condition, porcelain integrity, pilot tip geometry
Tip Acceptance Criteria
Values below are industry-typical. Always verify against OEM specification for the specific burner model in service.
Acceptance Criteria — Burner Tip Condition
| Parameter | Accept | Monitor / Condition | Replace | Notes |
|---|---|---|---|---|
| Orifice diameter deviation | < 5% oversize | 5–10% oversize | > 10% oversize | Measure with calibrated pin gauges |
| Orifice blockage | 0 blocked | 1 orifice partial | Any full block or ≥2 partial | Clean and re-measure before condemning tip |
| Surface cracking (thermal fatigue) | None visible | Hairline, no propagation | Branching or through-wall cracks | Risk of tip fragmentation at high flux |
| Orifice roundness (elongation) | Circular | Minor elongation — ≤5% | Visible key-holing | Affects jet velocity profile and flame stability |
Tip Cleaning Procedure — Offline
This procedure assumes the tip has been removed from an isolated, offline burner. For in-service removal, complete the Single Burner Isolation procedure above first.
Cleaning Media — Stainless Steel Tips
Do not use steel wire brushes on stainless steel or alloy tips — iron contamination promotes crevice corrosion. Use brass-wire brushes or non-metallic cleaning tools for 300-series stainless tips. Check tip material before selecting cleaning media.
Burner Tip Cleaning & Inspection — Offline
01
Confirm burner is isolated and LOTO applied
Verify all energy sources are isolated per the isolation procedure before touching the tip. Do not assume isolation — physically verify locked valves and check tags.
02
Remove tip assembly using correct tools
Use OEM-recommended tip puller or spanner. Do not use pipe extensions on standard wrenches — over-torquing damages the spud thread. Note orientation of directional tips before removal.
03
Record as-found condition
Photograph and note: carbon deposit locations, visible erosion, cracking, thread condition. As-found documentation supports condition-trend monitoring across turnarounds and justifies maintenance intervals.
04
Soak in approved solvent if heavily coked
Soak in site-approved hydrocarbon solvent for up to
30 minutes to soften hard carbon. Confirm solvent is compatible with tip material.
05
Clean orifices — brush and compressed air
Use appropriate-material brush on external surfaces. Use wooden or plastic picks to clear orifice deposits — do not use metal drills as drilling enlarges the orifice permanently. Flush with clean dry compressed air after brushing.
06
Measure orifice diameter — apply acceptance criteria
Check all orifices with calibrated pin gauges or precision drill bits. Record measured vs. nominal diameter for each orifice. Replace tip if outside OEM tolerance — do not continue service with an out-of-spec tip.
07
Inspect thread — clean and apply anti-seize
Check tip-to-spud thread for galling, stripping, or carbon buildup. Clean with wire brush. Apply approved high-temperature anti-seize compound to the male thread before reinstallation.
08
Reinstall tip — torque to OEM specification
Hand-tight first, then torque wrench to OEM value. Do not over-torque. For directional tips, verify orientation mark aligns before final torque application.
09
Verify tip alignment in quarl
Tip should be centred within the quarl opening with no mechanical contact with the refractory tile. Inspect quarl face for cracking or erosion — note any damage for repair scheduling at the next offline opportunity.
10
Record maintenance in equipment history log
Document: date, burner ID, as-found condition, work performed, orifice measurements (before and after), parts replaced, and as-left condition. Condition trends across turnarounds are the primary basis for optimising maintenance intervals.
Air Register Inspection & Lubrication
Air registers must move freely through their full range. A stiff or seized register prevents air-flow balancing and forces combustion adjustment through fuel alone — an inferior and potentially unsafe operating mode that limits the operator's ability to control excess air and flame shape.
In-Svc
In-Service Checks — Operator Rounds
Weekly or per site inspection schedule
- Move each register through full open/close range — note any stiffness or binding
- Confirm register setting matches the operator log / last documented position
- Check for visible fouling or debris lodged in louver blades
- Verify position indicator (if fitted) reads correctly against actual blade position
Offline
Offline Inspection — Heater Shutdown
Every turnaround / or on condition
- Remove register assembly where possible — inspect pivot pins for wear and fretting
- Check blade-to-frame seal in fully closed position — critical for purge effectiveness at startup
- Inspect louver blades for warping from thermal cycling
- Clean all deposit from blade surfaces and pivot points
- Apply high-temperature grease to pivot pins and actuating linkage
- Check actuating handle and locking mechanism — replace if worn or with excessive play
Register Position — Document Before Maintenance
Record the exact register position (% open or turns from closed) for every burner before any offline maintenance. Restore each register to its pre-maintenance setting as the starting point after return to service. Air rebalancing should be a deliberate, controlled operation — not an emergency adjustment during or immediately after restart.
Pilot Burner & Ignitor Maintenance
The pilot is the primary ignition source and the flame presence reference for BMS logic. A degraded pilot causes ignition failures, repeated re-light attempts, and elevated explosive atmosphere exposure during multiple ignition cycles.
Pilot & Ignitor Inspection Items
| Component | Check | Acceptance | Action if Failed |
|---|---|---|---|
| Ignitor electrode tip | Electrode gap measurement | 3–6 mm | Re-gap to OEM spec or replace electrode |
| Electrode porcelain insulator | Cracks, carbon tracking, glazing failure | No cracks or tracking | Replace electrode assembly — carbon tracking = guaranteed misfire |
| Electrode tip material | Erosion or melting of spark tip | Minimal erosion | Replace when tip visibly eroded or rounded |
| Pilot tip orifice | Carbon blockage; orifice erosion | Clear orifice; nominal diameter | Clean per tip cleaning procedure; replace if eroded |
| Pilot gas supply pressure | Upstream supply pressure at burner | Per OEM operating spec | Investigate supply line or pressure regulator |
| Ignition cable / lead | Insulation condition; connector security | No damage, chafing, or loose connections | Replace cable; secure all connectors |
| UV / IR flame detector | Lens cleanliness; self-check pass | Clear lens; self-check confirms pass | Clean lens; replace detector if self-check fails |
Ignition Testing — Purge and Confirm Gas-Free First
Never conduct a spark test or ignition function test in an area that may have gas present unless the burner is fully isolated. A spark in the presence of an uncontrolled gas release is a reliable ignition source. Confirm gas-free with a calibrated detector before any ignitor testing.
Critical Spares Management
Burner maintenance must not be held up waiting for parts — particularly during a hot-work window with the heater online. The minimum spares holding below supports timely response to common failures.
Minimum Critical Spares Holding — Per Burner Type in Service
| Component | Min. Qty on Hand | Rationale |
|---|---|---|
| Burner tip assembly (complete) | 2 per burner type | Enables immediate swap-and-clean: remove fouled tip, install clean spare, send removed tip to workshop — no delay on-site |
| Ignitor electrode assembly | 1 per burner | Electrodes are consumable items — gap erosion is expected with service hours; failures occur at startup |
| Pilot tip | 1 per burner type | Match to OEM part number exactly — do not substitute with alternative orifice sizes |
| Ignition cable / lead assembly | 2 per heater | Cable failure during startup halts the relight sequence entirely |
| Air register pivot pin set | 1 set per heater | Seized pins often require drill-out at turnaround — stocked parts prevent schedule delays |
| UV flame detector | 1 per heater | BMS-critical component — a failed detector may prevent light-off until replaced |
Tip Inventory Cycle
A clean, inspected, ready-to-install spare tip for each burner type eliminates cleaning delays during hot-work windows. The removed (fouled) tip is cleaned and inspected in the workshop and becomes the next spare — cycling through maintenance without holding up operations.
Return-to-Service Checks
Apply after any burner maintenance — in-service pull or full offline overhaul. Complete all steps before notifying the control room that the burner is available for light-off.
Return-to-Service — Burner Maintenance Complete
01
Confirm tip installed, aligned, and torqued
Physically verify tip is fully seated, alignment has been checked, and torque has been applied. No tip to be left hand-tight in service.
02
Confirm all tools and materials removed from burner front
All wrenches, brushes, cleaning materials, and personal PPE are clear of the burner area. Close front plate / access door if applicable. A tool left in the burner zone is a fire and projectile hazard on re-ignition.
03
Remove LOTO — obtain supervisor authorisation
Each worker removes their own lock only. Do not remove another person's lock under any circumstance. Supervisor sign-off required before energy restoration. Notify control room that isolation is being removed.
04
Restore pilot gas supply — verify pressure at burner
Open pilot gas supply valve slowly. Confirm pilot supply pressure at gauge vs. expected operating value for this burner model. Do not proceed if pressure is outside expected range.
05
Test pilot ignition — confirm flame established
Actuate ignitor per BMS sequence. Confirm pilot flame via observation port or UV detector signal. Pilot flame must be confirmed stable for ≥
10 seconds before proceeding to main burner energisation.
06
Open main fuel supply — increase gradually
Open the burner fuel gas block valve slowly. Flame should light promptly from pilot. If flame does not establish within
5 seconds, close fuel valve immediately — do not continue attempting light-off without investigating. Allow adequate purge before retry.
07
Observe flame shape and stability via peephole
Flame should be blue-rooted, symmetric, and stable with no impingement. Any yellow luminosity immediately after cleaning typically indicates residual solvent or cleaning media — monitor until it clears. Persistent yellow or smoking requires investigation.
08
Restore air register to pre-maintenance setting
Return register to the documented pre-maintenance position. Air rebalancing should be a controlled operation in normal operating conditions — not during startup or immediately after a hot-work window.
09
Monitor COT and pass temperatures — confirm stable
Allow
15–30 minutes for the heater to reach thermal equilibrium after adding the burner back to load. Confirm COT is within target range and pass temperature deviation is within normal limits.
10
Close hot-work permit — log completion in control room
Return signed permit to supervisor. Confirm in the control room log that maintenance is complete and the burner is back in service. File maintenance record with observations for the equipment history.