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NBBI Pressure Equipment Inspector (PEI) study materials
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NBBI Pressure Equipment Inspector (PEI) practice questions

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Question 1Boiler and Pressure Vessel Safety Inspection

Under the ASME Boiler and Pressure Vessel Code, what is the primary purpose of a hydrostatic test performed on a newly constructed pressure vessel?

  1. To calibrate the pressure relief valve set point
  2. To confirm the vessel's ability to operate continuously at maximum temperature
  3. To verify the vessel's structural integrity and detect leaks at a pressure above the design pressure Correct answer.
  4. To measure the exact elastic modulus of the shell material

Explanation

A hydrostatic test pressurizes the completed vessel with water, typically to 1.3 times the maximum allowable working pressure, to prove structural integrity and reveal leaks or weak joints. It does not measure material properties, establish temperature limits, or set relief valve values.

Question 2Boiler and Pressure Vessel Safety Inspection

A boiler inspector finds that a safety valve on a steam boiler is leaking continuously during normal operation. Which action is most appropriate?

  1. Repair or replace the leaking safety valve using qualified personnel Correct answer.
  2. Reduce the boiler firing rate until the valve reseats
  3. Ignore the leak because safety valves are designed to weep
  4. Increase the set pressure to stop the leak

Explanation

A safety valve that leaks continuously cannot reliably perform its overpressure protection function and must be repaired or replaced by qualified personnel. Adjusting firing rate or set pressure does not correct a defective valve and could compromise protection.

Question 3Boiler and Pressure Vessel Safety Inspection

What does the term 'maximum allowable working pressure' (MAWP) represent for a pressure vessel?

  1. The highest pressure permitted at the designated operating temperature, based on the weakest component Correct answer.
  2. The average operating pressure recorded over a year
  3. The pressure reached during the hydrostatic proof test
  4. The pressure at which the relief device must fully open

Explanation

MAWP is the maximum gauge pressure permissible at the top of a completed vessel in its normal operating position at a designated temperature, determined by the weakest element of the vessel. Relief devices are set relative to MAWP, and the hydrostatic test pressure exceeds it.

Question 4Boiler and Pressure Vessel Safety Inspection

During an internal inspection of a fire-tube boiler, the inspector observes pitting corrosion on the waterside of the shell. Which information is most important to determine whether the boiler can remain in service?

  1. The number of operators trained on the boiler
  2. The color of the corrosion products
  3. The date the boiler was last painted
  4. The depth of the pits relative to the allowable thickness Correct answer.

Explanation

Remaining thickness compared against the code-required minimum is the controlling factor for pitting corrosion fitness-for-service. Pit depth relative to allowable thickness determines whether repair, rerating, or retirement is needed.

Question 5Boiler and Pressure Vessel Safety Inspection

Which of the following best describes the function of a fusible plug in a fire-tube boiler?

  1. To melt and release steam or water when the crown sheet overheats due to low water Correct answer.
  2. To provide a low-water condition warning to the operator
  3. To regulate feedwater flow into the boiler
  4. To relieve excess steam pressure at the top of the shell

Explanation

A fusible plug contains a low-melting alloy that melts when the crown sheet is uncovered and overheats, releasing steam or water to warn of the low-water condition and reduce the risk of crown sheet failure. It is a low-water safeguard, not a pressure relief or feedwater control device.

Question 6Boiler and Pressure Vessel Safety Inspection

An inspector is reviewing the nameplate of a pressure vessel. Which item is normally required to be stamped on the nameplate per the ASME Code?

  1. The manufacturer's home address
  2. The name of the authorized inspector's employer
  3. The vessel's shipping weight
  4. The MAWP and the minimum design metal temperature Correct answer.

Explanation

The ASME Code requires the nameplate to show essential design data, including the MAWP and the minimum design metal temperature, along with the manufacturer, year built, and certification mark. Addresses, inspector employers, and shipping weights are not required nameplate data.

Question 7Boiler and Pressure Vessel Safety Inspection

What is the purpose of a try lever on a safety valve?

  1. To lock the valve in the closed position during operation
  2. To measure the steam flow through the valve
  3. To adjust the blowdown ring setting
  4. To manually lift the disc and verify the valve opens freely Correct answer.

Explanation

The try lever allows an operator to manually lift the valve disc to confirm the valve is free to open, an important periodic operational check. It does not lock the valve, set blowdown, or measure flow.

Question 8Boiler and Pressure Vessel Safety Inspection

Which condition most directly indicates that a pressure relief valve on an air receiver should be replaced rather than adjusted?

  1. The valve is mounted vertically
  2. The valve body is painted the wrong color
  3. The valve seat is badly corroded and cannot be reseated Correct answer.
  4. The valve was installed last year

Explanation

Severe seat corrosion prevents reliable reseating and cannot be corrected by adjustment, so replacement is required. Color, mounting orientation, and recent installation are not indicators of internal seat damage.

Question 9Boiler and Pressure Vessel Safety Inspection

In a water-tube boiler, what is the primary consequence of operating with a low water level that exposes the upper tubes?

  1. Increased feedwater temperature
  2. Overheating of tubes and possible tube rupture Correct answer.
  3. Reduced steam demand from the plant
  4. Improved circulation in the waterwall

Explanation

When tubes are uncovered, water cannot remove heat from the metal, causing rapid overheating that can lead to bulging or rupture. Low water does not reduce steam demand or improve circulation; it creates a serious hazard.

Question 10Boiler and Pressure Vessel Safety Inspection

An inspector is evaluating a welded joint on a pressure vessel. Which document provides the qualified welding procedure and the ranges of essential variables under which the joint may be made?

  1. The vessel's operating manual
  2. The material test report
  3. The welding procedure specification supported by a procedure qualification record Correct answer.
  4. The relief valve data sheet

Explanation

The welding procedure specification (WPS) defines how the weld is to be made, and the procedure qualification record (PQR) documents the test results proving the procedure produces sound welds within its essential variable ranges. Material test reports, operating manuals, and relief valve data sheets do not qualify welding procedures.

Question 11Boiler and Pressure Vessel Safety Inspection

A pressure vessel is to be rerated to a lower MAWP because of wall thinning found during inspection. Which approach is most appropriate?

  1. Weld a patch over the thinned area without documentation
  2. Increase the operating temperature to compensate
  3. Reduce the relief valve set pressure without any calculation
  4. Recalculate the allowable pressure using the measured remaining thickness and current code rules, then update the nameplate Correct answer.

Explanation

Rerating requires a documented calculation using measured remaining thickness and the applicable code formulas to establish a new, lower MAWP, followed by nameplate revision and relief device adjustment. Arbitrary changes or undocumented patches are not acceptable.

Question 12Boiler and Pressure Vessel Safety Inspection

What is the significance of the minimum design metal temperature (MDMT) marked on a pressure vessel nameplate?

  1. It is the temperature at which the relief valve freezes
  2. It is the lowest temperature at which the vessel may be operated without impact-testing exemptions Correct answer.
  3. It is the minimum steam temperature required for startup
  4. It is the lowest ambient temperature the paint can withstand

Explanation

The MDMT establishes the lowest metal temperature at which the vessel may be operated while retaining adequate toughness, considering impact-testing requirements and material selection. It is not a paint rating, a relief valve limit, or a startup steam temperature.

Question 13Boiler and Pressure Vessel Safety Inspection

During an external inspection, an inspector notes that insulation on a vessel has been removed and not replaced, exposing the shell to weather. Which concern is most relevant?

  1. Increased relief valve capacity
  2. Loss of nameplate readability
  3. Increased risk of external corrosion, particularly under moisture-retaining conditions Correct answer.
  4. Reduced vessel weight requiring recalculation

Explanation

Exposed carbon steel shells are subject to atmospheric corrosion, and where moisture can collect, corrosion can accelerate. Insulation removal does not change relief capacity or require weight recalculation, and nameplate readability is a separate issue.

Question 14Boiler and Pressure Vessel Safety Inspection

An inspector observes that a safety valve on a boiler has a drain hole plugged with scale. Why is this significant?

  1. The drain hole controls the set pressure
  2. The drain hole measures steam quality
  3. The drain hole is decorative and has no function
  4. The drain hole allows condensate to escape so it does not interfere with valve operation Correct answer.

Explanation

The drain hole in the valve body allows condensate to drain away, preventing water from collecting and affecting valve performance or causing corrosion. Plugging it can impair operation. It does not set pressure or measure steam quality.

Question 15Boiler and Pressure Vessel Safety Inspection

Which of the following conditions would most likely require the inspector to recommend a hydrostatic test of an existing boiler?

  1. The boiler's feedwater pump was recently serviced
  2. The boiler has been idle and laid up for an extended period with unknown internal condition Correct answer.
  3. The boiler's operating log shows steady performance
  4. The boiler's paint is fading

Explanation

A hydrostatic test is commonly required when a boiler has been out of service with uncertain internal condition, after major repairs, or when integrity must be verified. Fading paint, steady logs, and pump servicing do not by themselves justify a hydrostatic test.

Question 16Boiler and Pressure Vessel Safety Inspection

What is the primary reason the ASME Code requires impact testing of certain pressure vessel materials?

  1. To ensure adequate notch toughness and resistance to brittle fracture at low temperature Correct answer.
  2. To determine the thermal conductivity of the material
  3. To measure hardness for wear resistance
  4. To verify the weldability of the material

Explanation

Impact testing evaluates notch toughness so that materials used at low temperature will resist brittle fracture. It is not a hardness, thermal conductivity, or weldability test.

Question 17Boiler and Pressure Vessel Safety Inspection

An inspector finds that a pressure vessel's relief valve is installed downstream of a block valve that is closed. What is the correct assessment?

  1. This is acceptable because relief valves are redundant
  2. This is acceptable if the block valve is locked open
  3. This is acceptable if the block valve is tagged
  4. This is a serious deficiency because the relief path is blocked, defeating overpressure protection Correct answer.

Explanation

A closed block valve between the vessel and its relief device isolates the protection and is a serious deficiency. A block valve may only be permitted if it can be locked or sealed in the open position so the relief path remains available.

Question 18Boiler and Pressure Vessel Safety Inspection

Which inspection method is most commonly used to detect surface-breaking cracks in a welded pressure vessel shell without removing the weld?

  1. Ultrasonic thickness gauging
  2. Magnetic particle testing Correct answer.
  3. Radiographic testing
  4. Hydrostatic proof testing

Explanation

Magnetic particle testing detects surface and near-surface discontinuities in ferromagnetic materials and can be applied to weld surfaces. Radiography and ultrasonic thickness gauging serve other purposes, and hydrostatic testing is a proof test rather than a crack-detection method.

Question 19Boiler and Pressure Vessel Safety Inspection

A boiler inspector is reviewing records and finds that the last internal inspection was performed more than the code-required interval ago. What is the most appropriate action?

  1. Waive the requirement because the boiler has operated without incident
  2. Continue operation until the next scheduled outage
  3. Recommend that the boiler be inspected promptly and document the overdue condition Correct answer.
  4. Extend the interval by one year without justification

Explanation

Overdue inspections are a compliance deficiency that should be documented and corrected promptly; continued operation without inspection increases risk. Incident-free operation and administrative waiver do not substitute for the required inspection.

Question 20Boiler and Pressure Vessel Safety Inspection

What is the function of a blowdown ring on a safety valve?

  1. To prevent the valve from opening
  2. To adjust the blowdown, the pressure difference between opening and reseating Correct answer.
  3. To measure the steam pressure
  4. To increase the valve's flow capacity

Explanation

The blowdown ring is adjusted to control the blowdown, which is the difference between the set pressure and the reseating pressure, helping the valve reseat properly after relieving. It does not change capacity, prevent opening, or measure pressure.

Question 21Boiler and Pressure Vessel Safety Inspection

An inspector observes that a pressure vessel has been modified by the addition of a nozzle without documentation. Which course of action is most consistent with code requirements?

  1. Remove the nozzle only if it leaks
  2. Require that the modification be evaluated, documented, and approved by a qualified party Correct answer.
  3. Accept the nozzle because it appears to be well welded
  4. Ignore the modification if the vessel is not in a high-risk service

Explanation

Alterations to pressure vessels must be evaluated and documented in accordance with code requirements, typically with engineering review and inspection. Visual appearance or service classification does not substitute for documented approval.

Question 22Boiler and Pressure Vessel Safety Inspection

A pressure vessel is constructed of material with a specified minimum yield strength used in the design formula. If the actual measured yield strength of the delivered plate is higher than specified, what is the effect on the allowable working pressure calculation?

  1. The MAWP is unaffected because yield strength is not used in design
  2. The MAWP is reduced proportionally
  3. The MAWP may be increased without limit based on the higher measured strength
  4. The MAWP is still based on the code-specified minimum properties unless a documented rerating is performed Correct answer.

Explanation

Design calculations use code-specified minimum material properties, not incidental higher values from a particular heat. Increasing the MAWP requires a formal rerating with documented justification and inspection.

Question 23Boiler and Pressure Vessel Safety Inspection

During a hydrostatic test, the inspector observes that the test pressure drops slightly and then stabilizes while the vessel remains at constant temperature. What is the most likely explanation?

  1. The gauge is defective and should be ignored
  2. The relief valve has opened and stayed open
  3. The vessel has failed catastrophically
  4. The vessel is absorbing water into the test medium or the system is equalizing, requiring investigation before acceptance Correct answer.

Explanation

A small initial pressure drop that stabilizes may result from air entrapment, system equalization, or minor absorption, but it must be investigated and confirmed before acceptance. It does not automatically indicate catastrophic failure, and ignoring gauge behavior is not acceptable.

Question 24Boiler and Pressure Vessel Safety Inspection

An inspector must evaluate a vessel that has experienced a fire. Which factor is most important in determining whether the vessel can be returned to service?

  1. Whether the material has been subjected to temperatures that could alter its mechanical properties Correct answer.
  2. The color of the soot on the exterior
  3. The number of fire extinguishers used
  4. The duration of the fire alone

Explanation

Fire exposure can raise metal temperatures enough to change microstructure and mechanical properties, so the evaluation must determine whether properties were affected, often requiring metallurgical testing and engineering assessment. Soot color, extinguisher count, and duration alone are insufficient.

Question 25Boiler and Pressure Vessel Safety Inspection

A lap seam joint is found on an older boiler shell. Why does this detail receive special attention from an inspector?

  1. Lap seams are always stronger than butt seams
  2. Lap seams can concentrate stress and are prone to grooving and cracking, requiring careful evaluation Correct answer.
  3. Lap seams improve water circulation
  4. Lap seams eliminate the need for rivets

Explanation

Lap seam joints create stress concentrations and are susceptible to grooving and cracking, particularly in older riveted boilers, so they warrant careful inspection and evaluation. They are not inherently stronger, do not eliminate rivets, and do not affect circulation.

Question 26Boiler and Pressure Vessel Safety Inspection

An inspector is reviewing the required markings on a boiler's stamping. Under the ASME Boiler and Pressure Vessel Code, which item must appear on the stamping of a fired steam boiler?

  1. The economizer tube count
  2. The feedwater pump model designation
  3. The maximum allowable working pressure Correct answer.
  4. The burner manufacturer's serial number

Explanation

The Code requires the maximum allowable working pressure to be marked on the boiler so that operators and inspectors know the pressure limit for safe operation. Other design details such as burner data or tube counts are recorded elsewhere and are not part of the required stamping.

Question 27Boiler and Pressure Vessel Safety Inspection

A safety valve on a steam boiler is observed to have its test lever wire-sealed in place. What is the inspector's most appropriate conclusion?

  1. The seal proves the valve has never been tested
  2. The seal is required only on hot water boilers
  3. The seal indicates the valve was set and sealed after testing and should be verified by lifting Correct answer.
  4. The valve has been disabled and must be replaced immediately

Explanation

Sealing or wire-sealing a test lever is normal practice after a valve has been set and tested, to deter tampering. The inspector should still verify the valve can be lifted and that the seal is intact and properly applied, rather than assuming either failure or perfection.

Question 28Boiler and Pressure Vessel Safety Inspection

During an internal inspection of a fire-tube boiler, the inspector finds pitting on the shell beneath a wet bottom area. Which action best characterizes the inspector's role?

  1. Recommend immediate replacement of the entire shell regardless of depth
  2. Approve continued operation at the original pressure without further evaluation
  3. Measure and record the extent, then evaluate remaining thickness against the Code minimum Correct answer.
  4. Defer the finding to the boiler operator for a decision

Explanation

The inspector must quantify corrosion damage, typically by measuring remaining wall thickness, and then compare it with the minimum thickness allowed for the intended pressure. Decisions about repair, rerate, or retirement follow from that evaluation rather than from assumption.

Question 29Boiler and Pressure Vessel Safety Inspection

What is the primary purpose of the fusible plug installed in the crown sheet of a fire-tube boiler?

  1. To indicate the water level visually to the operator
  2. To relieve excess steam pressure during overfiring
  3. To warn of low water by melting and releasing steam into the furnace Correct answer.
  4. To drain condensate from the steam drum

Explanation

A fusible plug contains a low-melting alloy that melts when the crown sheet is uncovered and overheats, releasing steam and water into the furnace as a warning. It is a low-water safeguard, not a pressure relief device.

Question 30Boiler and Pressure Vessel Safety Inspection

An inspector examines a pressure vessel and finds a crack at a weld toe that is open to the surface. Which nondestructive examination method is best suited to confirm and size this surface-breaking indication?

  1. Magnetic particle testing Correct answer.
  2. Acoustic emission monitoring
  3. Radiography
  4. Ultrasonic thickness gauging

Explanation

Magnetic particle testing is well suited to detecting and outlining surface-breaking discontinuities in ferromagnetic welds. Radiography and ultrasonic thickness gauging are oriented toward internal features or wall loss, and acoustic emission monitors activity rather than sizing a specific crack.

Question 31Boiler and Pressure Vessel Safety Inspection

Which document establishes that a repair organization is permitted to weld on a Code-stamped pressure vessel?

  1. The vessel's operating manual
  2. The purchaser's insurance policy
  3. The original bill of sale
  4. A valid ASME Certificate of Authorization with the appropriate stamp Correct answer.

Explanation

Repairs and alterations to Code vessels must be performed by organizations holding the appropriate ASME Certificate of Authorization and stamp. Operating manuals, insurance documents, and sales records do not confer welding authority.

Question 32Boiler and Pressure Vessel Safety Inspection

A hot water heating boiler is equipped with a low-water cutoff. What is the function of this control?

  1. To regulate the temperature of the supply water
  2. To open the safety valve at set pressure
  3. To limit the maximum steam pressure
  4. To stop burner operation when the water level falls below a safe point Correct answer.

Explanation

The low-water cutoff is a safety control that shuts off the burner when water level drops below a safe limit, preventing overheating of surfaces. It is distinct from pressure and temperature controls.

Question 33Boiler and Pressure Vessel Safety Inspection

During an external inspection, an inspector notices steam leaking from a threaded fitting on a boiler. What is the most appropriate immediate action?

  1. Note it for the next scheduled inspection
  2. Ignore it because threaded joints commonly weep
  3. Increase operating pressure to reseat the joint
  4. Recommend repair and evaluate whether the boiler should be taken out of service until corrected Correct answer.

Explanation

A steam leak at a threaded joint can indicate a failing connection and poses a hazard to personnel and equipment. The inspector should recommend prompt repair and assess whether continued operation is safe until the repair is made.

Question 34Boiler and Pressure Vessel Safety Inspection

An inspector is determining the required frequency of internal inspection for a boiler. Which factor most directly governs the interval?

  1. The number of operators employed at the plant
  2. The color of the boiler casing
  3. The jurisdictional requirements and the boiler's condition and service history Correct answer.
  4. The manufacturer's advertising literature

Explanation

Inspection intervals are set by the applicable jurisdiction and adjusted based on the boiler's condition, service, and history. Cosmetic features, staffing, and marketing materials do not determine inspection frequency.

Question 35Boiler and Pressure Vessel Safety Inspection

A pressure vessel has been in caustic service, and the inspector suspects caustic embrittlement cracking near riveted seams. Which examination approach is most appropriate?

  1. Wet fluorescent magnetic particle testing of suspect seams after surface preparation Correct answer.
  2. Ultrasonic thickness measurement of the heads
  3. Visual examination of the exterior only
  4. Hydrostatic testing without any surface examination

Explanation

Caustic embrittlement produces fine surface-breaking cracks, often at seams and stressed regions, so sensitive surface methods such as wet fluorescent magnetic particle testing are appropriate. Thickness measurement and hydrostatic testing alone would not reveal such cracks.

Question 36Boiler and Pressure Vessel Safety Inspection

An inspector finds that a boiler's safety valve has been set to open above the maximum allowable working pressure marked on the boiler. What is the correct interpretation?

  1. The boiler stamping should be changed to match the valve
  2. This is acceptable because valves lose accuracy over time
  3. No action is needed if the boiler rarely reaches that pressure
  4. The valve setting must be corrected to comply with the Code limit Correct answer.

Explanation

Safety valves must be set so they do not permit pressure to exceed the Code limit relative to the boiler's maximum allowable working pressure. A setting above that limit must be corrected, not accommodated by altering the stamping.

Question 37Boiler and Pressure Vessel Safety Inspection

A welded pressure vessel shows laminar-type indications parallel to the plate surface on ultrasonic examination. What condition does this most likely represent?

  1. Stress corrosion cracking at a nozzle
  2. Lamination or inclusion in the plate material Correct answer.
  3. Weld undercut at the cap
  4. Through-thickness cracking from fatigue

Explanation

Indications oriented parallel to the plate surface and planar in the through-thickness direction commonly correspond to laminations or inclusion bands from the steelmaking process. Fatigue cracks and stress corrosion cracks generally orient differently and are not parallel to the rolling plane.

Question 38Boiler and Pressure Vessel Safety Inspection

An inspector is reviewing the hydrostatic test of a new pressure vessel. At what point during the test should the inspector examine the vessel for leaks?

  1. Before any pressure is applied
  2. Only after the pressure has been fully released
  3. While the vessel is held at the specified test pressure Correct answer.
  4. Only after the vessel has operated for one week

Explanation

The leak examination is performed while the vessel is held at the required test pressure, since leaks may close or become indistinct once pressure is released. Examining before pressurization or after operation would not satisfy the test intent.

Question 39Boiler and Pressure Vessel Safety Inspection

An inspector notes that a pressure vessel's support skirt has cracked at the attachment weld to the shell. Why is this finding significant?

  1. It indicates the relief valve is undersized
  2. It proves the vessel was improperly heat treated
  3. It only affects the vessel's appearance
  4. It can transfer unexpected loads and lead to shell cracking or instability Correct answer.

Explanation

Cracks at a support skirt attachment can redistribute loads into the shell and compromise structural stability, potentially leading to shell cracking. The finding is structural, not cosmetic, and is unrelated to relief valve sizing.

Question 40Boiler and Pressure Vessel Safety Inspection

A boiler inspector observes that the water column and gauge glass connections are partially blocked with sludge. What is the most serious consequence?

  1. Higher stack temperature
  2. Reduced steam quality only
  3. False water level indication leading to unsafe operation Correct answer.
  4. Increased fuel consumption

Explanation

Blocked water column or gauge glass connections can give a false water level reading, which may lead operators to mismanage feedwater and risk low-water conditions. This is a direct safety concern rather than an efficiency issue.

Question 41Boiler and Pressure Vessel Safety Inspection

An inspector finds that a pressure vessel's nameplate is missing. What is the most appropriate course of action?

  1. Assume the vessel is unrated and remove it from service permanently
  2. Investigate records and, where justified, have the vessel marked in accordance with the Code Correct answer.
  3. Ignore the missing plate if the vessel appears sound
  4. Stamp a new nameplate using the inspector's own estimate of MAWP

Explanation

A missing nameplate requires investigation of construction records and, if the vessel can be properly identified and evaluated, remarking in accordance with Code requirements. Neither permanent removal nor inspector-invented stamping is appropriate.

Question 42Boiler and Pressure Vessel Safety Inspection

During inspection of a cast iron boiler section, the inspector finds a crack extending through a section wall. Why does this finding generally preclude welded repair?

  1. Welding would change the boiler's stamping
  2. Cast iron has low ductility and welding commonly produces cracking and unreliable repairs Correct answer.
  3. Cast iron is too expensive to weld
  4. Cracks in cast iron are always harmless

Explanation

Cast iron has low ductility and poor weldability, so welded repairs are generally unreliable and prone to further cracking. For this reason, cracked cast iron sections are typically replaced rather than welded.

Question 43Boiler and Pressure Vessel Safety Inspection

An inspector observes that a pressure relief valve discharge pipe on a steam vessel is fitted with a valve that can be closed. What concern does this raise?

  1. It reduces noise to acceptable levels
  2. It can block the relief path and defeat overpressure protection Correct answer.
  3. It is required by the Code for all steam vessels
  4. It improves valve performance

Explanation

Any valve in a relief valve discharge line that can be closed may isolate the relief device and defeat its overpressure protection. Relief discharge paths must remain unobstructed unless specific Code provisions for locked-open arrangements are satisfied.

Question 44Boiler and Pressure Vessel Safety Inspection

A pressure vessel is to be pneumatically tested instead of hydrostatically tested. Which precaution is most important because of the stored energy involved?

  1. Using water as the test medium
  2. Restricting access and using remote monitoring during pressurization Correct answer.
  3. Increasing the test pressure above the hydrostatic test value
  4. Eliminating all inspection during the test

Explanation

Pneumatic testing stores far more energy than hydrostatic testing, so personnel must be kept away from the vessel during pressurization and monitoring should be remote where practicable. Using water would make the test hydrostatic, and raising pressure above the hydrostatic value is not permitted.

Question 45Boiler and Pressure Vessel Safety Inspection

An inspector finds that a vessel's post-weld heat treatment record is missing for a thick-wall carbon steel vessel in wet H2S service. Why is this record significant?

  1. It documents paint color and finish
  2. It is required only for stainless steel vessels
  3. It affects hardness and residual stress, which influence cracking resistance Correct answer.
  4. It proves the vessel was hydrostatically tested

Explanation

Post-weld heat treatment reduces residual stress and hardness in weldments, both of which strongly influence susceptibility to cracking in wet H2S service. Its absence must be investigated because it affects fitness for service.

Question 46Boiler and Pressure Vessel Safety Inspection

An inspector observes that a boiler's main steam stop valve is leaking through when closed. Why is this condition important during an internal inspection?

  1. It prevents the boiler from being properly isolated, creating an entry hazard Correct answer.
  2. It indicates the safety valve is set too low
  3. It improves isolation for safe entry
  4. It has no effect on inspection safety

Explanation

A leaking stop valve can allow steam or hot water to enter the boiler while personnel are inside, so proper isolation with blinds or equivalent means is essential. The condition is a personnel safety issue during internal inspection.

Question 47Boiler and Pressure Vessel Safety Inspection

A pressure vessel in hydrogen service shows blistering and stepwise cracking on the inner surface. Which damage mechanism is most consistent with these findings?

  1. Hydrogen-induced cracking Correct answer.
  2. Graphitization of carbon steel
  3. Chloride stress corrosion cracking
  4. Erosion-corrosion from particulates

Explanation

Blistering with stepwise cracking is characteristic of hydrogen-induced cracking in wet sour or hydrogen-charging service. Chloride stress corrosion cracking typically appears as branched cracks in austenitic stainless steel, and graphitization occurs at elevated temperature.

Question 48Boiler and Pressure Vessel Safety Inspection

An inspector is evaluating a vessel that has been in service for 30 years with no documented creep-resistant alloy verification. The vessel operates near its design temperature. Which action is most appropriate?

  1. Reduce inspection frequency because the vessel has operated without failure
  2. Increase operating temperature to test material performance
  3. Verify material composition and evaluate creep damage before continued service Correct answer.
  4. Assume the material is as originally specified and continue operation

Explanation

At elevated temperature, material composition and accumulated creep damage strongly affect remaining life, so verification and evaluation are needed. Assuming original specification or reducing inspection is not justified, and raising temperature would accelerate damage.

Question 49Boiler and Pressure Vessel Safety Inspection

A pressure vessel's manway cover gasket has been replaced with a non-Code gasket material rated below the design temperature. What is the inspector's primary concern?

  1. The gasket color may not match the original
  2. The vessel's stamping must be removed
  3. The gasket may fail and cause leakage at operating conditions Correct answer.
  4. The relief valve must be resized

Explanation

A gasket rated below the design temperature may not seal reliably at operating conditions, creating a leakage hazard. Gasket selection must be suitable for the design temperature and pressure, independent of cosmetic considerations.

Question 50Boiler and Pressure Vessel Safety Inspection

An inspector finds that a pressure vessel's inspection opening cover is secured with bolts of a lower grade than specified. Why is this significant?

  1. Bolt grade affects only appearance
  2. The cover may not remain sealed at design pressure, creating a leak or failure risk Correct answer.
  3. Lower grade bolts are easier to install
  4. The bolts will require more frequent painting

Explanation

Bolting must be adequate for the design pressure and temperature to keep the cover sealed and structurally secure. Substandard bolts can yield or fail, leading to leakage or sudden release.