Section 15 — Inspection

In-Plant Inspection of Existing Boilers

IPE Engineering Practice IPE-EP-15-4-5

Document number: IPE-EP-15-4-5 · Section: 15 — Inspection

SCOPE

• This Practice defines the requirements and specifies responsibilities for the internal and external inspection of direct fired boilers. It is not intended to replace any jurisdictional inspection requirements which specify the use of third party authorized inspectors but this Practice serves to supplement such requirements.
• Any deviation from this Practice must be approved by the procedure described in EP 1–1–3.
• An asterisk (*) indicates that an action by the Owner or the Stationary Equipment Inspection Authority is required.

2.0 REFERENCES

The latest edition of the following standards and publications are referred to herein:

STANDARDS AND PUBLICATIONS

DEFINITIONS

• Boiler External Inspection – Visual inspection of the boiler external parts while boiler is either in or out of operation.
• Boiler Internal Inspection – A combination of visual and NDE examination of the internal parts of the boiler while it is out of service and entry to the drums, firebox, and convection sections are possible.
• Stationary Equipment Inspection Authority – For the purposes of this Practice the Stationary Equipment Inspection Authority is the Plant Chief Inspector, Inspection Supervisor, or Chief Inspection Engineer as defined by the Plant management.

INSPECTION PERSONNEL

• Personnel performing inspection of boilers and their components shall be qualified in accordance with EP 15–3–1, except that the responsible plant inspector must be qualified to the National Board Inspection Code.
• In most locations, the statutory inspection shall be performed by a third party inspector, certified by the jurisdiction, at intervals determined by the jurisdiction.
• Personnel performing NDE, refractory inspection, or other inspections shall be qualified for the type work they are doing by their employer. The Stationary Equipment Inspection Authority shall review evidence of their qualification

GENERAL

• Refer to API 573 for detailed guidance for the inspection of fired boilers

EXTERNAL INSPECTION

• External inspection of boilers may be performed while the unit is in operation. The following items shall be inspected:
• Ladders, walkways, platforms, and stairways for the following conditions:
• Corroded, bent, broken, or missing structural parts.
• Loose, corroded, or missing bolting.
• Worn stair treads and rungs.
• Foundations of boiler supports for evidence of spalling, cracking, settling, and deterioration.
• Furnace walls for evidence of corrosion, warpage, discoloration, or excessively high surface temperature.
• Piping connections for leakage, and distortion.
• Accessory pressure parts, including boiler drums, fittings, headers, and external downcomers for leakage.
• Water columns and gauge glasses for leakage or blockage.
• All associated mechanical equipment (pumps, fans, preheaters, etc.) for excessive vibration, noise, or abnormal operation.
• Induced draft fans for signs of erosion, or corrosion.
• Soot blowers for packing leaks and evidence of warpage.
• Air and flue–gas ducts and stacks for evidence of leaks or buckling.
• Air preheaters for evidence of fouling and corrosion.
• Blowdown equipment and safety valves for evidence of leakage or abnormal operation.
• Bellows and expansion joints for abnormal deformations, cracks, corrosion, or erosion.
• Burners and associated hardware for excessive oxidation and mechanical degradation.

INTERNAL INSPECTION

• It is recommended that a preliminary inspection be made of accessible internal surfaces of boiler shells, drums, tubes, furnaces, and gas passages, before any cleaning is performed, noting the amount and appearance of scale and sludge deposits. If the source or corrosivity of the deposits or sludge is of concern, the inspector may request a chemical analysis of them.

• After cleaning the boiler internal parts and weld joints as indicated by the inspector, a thorough internal inspection shall be performed including, but not restricted to, the following items as deemed necessary by the inspector:
• Refractory linings in the combustion chamber, stacks, flue gas ducts, observation and access doors, and around burners for deterioration. Refer to EP 15–4–8 for more detail on refractory inspection.
• The firebox casing for evidence of corrosion or air leakage.
• Internal surfaces of drums and connections to drums for deformation, corrosion, pitting, grooving, scale deposits, and sludge.
• At the inspector’s discretion the top external surface of mud drums may be cleaned and examined for corrosion.
• Weld seams shall be examined for corrosion, grooving, and cracking. Any cracking in the pressure boundaries shall be evaluated by personnel skilled in performing such evaluations.
• If the boiler is of riveted construction, rivets and lap seams shall be checked for tightness. Water deposits around a rivet may indicate it is loose or broken, dampness or deposits along a seam indicate it may be leaking.
• Ultrasonic thickness measurements of drums shall be obtained as deemed necessary in order to determine ongoing corrosion rates of the shells and heads. Thinned or corroded areas shall be measured with an ultrasonic thickness caliper and recorded for evaluation and future reference.
• Safety valve nozzles and gauge glass connections to drums shall be examined for evidence of corrosion, clogging or sludge accumulation.
• Drum internals, including steam separators and baffles, shall be checked for tightness, corrosion, and deterioration.
• Tubes, downcomers, and risers shall be inspected for scale, build–up deposits, erosion, and corrosion.
• When accessible the inside surface of water headers for corrosion and erosion.
• Superheater headers for corrosion and erosion.
• Accessible tubes for evidence of overheating, corrosion, and erosion.
• Water wall tubes and generating tubes shall be examined for bulging, blistering, quench cracking, sagging, pitting, and bowing.
• Wall thickness measurements and tube diameters shall be measured in random locations and especially in areas of flame impingement or high temperature.
• Water wall tube alignment shall be checked.
• Baffles shall be checked for displacement or fall–out.
• Damper support brackets, driving rods, and pins shall be examined for wear and proper operation.

REPAIRS AND ALTERATIONS

• In certain locations, the Authorized Inspector must approve repairs or alterations prior to performing the work. In such cases jurisdictional requirements shall be reviewed to ensure compliance with the applicable laws before the work is performed.
• Boiler repairs and alterations shall be performed in strict conformance with jurisdictional requirements, National Board Code and ASME Boiler Code, Section I.

FINAL INSPECTION

• Upon completion of all inspection and required work, the boiler shall receive a re–inspection of all work to ensure its completeness and adequacy.
• In cases requiring jurisdictional authorized inspection of repairs and alterations the Authorized Inspector shall be notified and given opportunity to inspect the completed work.
• If necessary, final pressure tests of the boiler shall be witnessed as required by the jurisdiction and the appropriate information recorded and placed in the boiler inspection file.

RECORDS AND DOCUMENTATION

• Inspection findings shall be reported in sufficient detail to permit relocation and evaluation of each reported condition. The information shall be recorded on a sketch or inspection form that accurately identifies the findings that have been observed.
• Additional notes, sketches, or documents shall be appended to the boiler inspection drawing, sketch, or form if required to more fully describe the inspection findings.
• The recorded information shall be filed in the boiler inspection file for future referral.
• Thickness readings obtained at monitoring locations should be used to calculate corrosion rates, remaining life, and next inspection dates apart from the jurisdictional required inspections performed by the Authorized Inspector.

RESPONSIBILITIES

• The Stationary Equipment Inspection Authority or his delegate shall be responsible to:
• Serve as final authority on all matters concerning inspection, including final acceptance.
• Assign personnel associated with the Inspection Operation
• The Maintenance Supervisor (Resource Allocator) or his delegate shall be responsible to:
• Notify the inspector when a boiler has been opened, cleaned, and flushed, and is ready for internal inspection.
• Support any required operations involving boiler repair or alteration.
• The Inspector shall be responsible to:
• Perform external and internal inspection of the boiler and components in accordance with this procedure.
• Perform a cursory inspection to determine if cleaning is needed, and to what extent, to achieve a satisfactory thorough inspection.
• When appropriate, take digital ultrasonic thickness readings of tubes, drums, and associated equipment.
• Provide a sketch of the boiler marked to indicate inspection findings and the location of findings.
• Evaluate inspection findings and recommend any necessary repairs.
• Prepare required Inspection Repair Scopes.
• Witness all repairs and alterations that might be required.
• Perform final inspection of the boiler before closing.
• Observe the final pressure test of the boiler, if required.
• The Operations Department Representative shall be responsible to:

• Determine cleanliness for satisfactory operation of boilers.
• Witness closing of boiler manways, and sign–off for boiler closing.

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