What this is
What is a pressure vessel inspection?
What is a pressure vessel inspection?
A pressure vessel inspection is the examination of a specific vessel and its safety devices for corrosion, damage and correct operation, carried out at the interval set by the governing written scheme. It produces a pass, fail or restricted-use outcome, and where required, a certificate.
Who can carry out the inspection?
Someone whose competence matches what the governing scheme or regulation requires for the vessel in question, which in most regimes means an accredited inspection body or an insurer's inspector, and in lower-consequence cases an in-house competent person. The record should show which of these carried out the examination, because the standing of the inspector is part of what makes the record defensible.
Is this the same thing as the written scheme?
No. The written scheme is the governing plan that says which parts of a pressure system need examining, by what method, and at what interval. This record is one examination carried out against that scheme, for one vessel, on one date. A scheme can be excellent and an individual inspection still be done badly, or vice versa.
Scope
When is a pressure vessel inspection required?
This inspection is one step in a larger statutory examination programme. Using it for condition monitoring that is not driven by a statutory interval, or for a system-level document that should define the scheme rather than execute against it, produces a record that answers the wrong question later.
Use this template when
- The vessel's statutory or scheme-set inspection interval has arrived, or is about to
- The vessel has been modified, repaired or has failed a previous examination and needs a follow-up
- A post-incident examination is required after an operating upset or a suspected overpressure event
- A new record is needed for a vessel entering the asset register, establishing its inspection baseline
- The governing written scheme requires this examination to keep the vessel in date
Do not use it for
- Pressure System Written Scheme, which defines what needs examining, how, and at what interval across the whole system, rather than executing one examination against it
- Asset Condition Inspection, which assesses the general condition of an asset against defined criteria rather than a statutory pressure examination
- Vibration Analysis Record, which records vibration readings from rotating equipment, not vessel shell or thickness data
- Thermographic Survey, which records infrared images to find hot spots on electrical panels, motors and bearings
- Anything outside KnowMaintain, which belongs in the workspace that owns that process
Compliance mapping
Which ASME BPVC requirements does this satisfy?
The design and construction of the vessel is heavily codified; the in-service examination that keeps it safe to operate is governed separately, by whichever regime applies to the site, and it is that in-service regime this record has to satisfy.
| Clause | Requirement | Where it lands |
|---|---|---|
| ASME BPVC Section VIII, Div.1 | Design basis of the vessel, including maximum allowable working pressure, against which in-service findings are judged | Header |
| National Board Inspection Code, Part 2 | Scope, method and interval for in-service external examination of pressure vessels | External examination |
| National Board Inspection Code, Part 2 | Internal examination and thickness survey requirements, including minimum thickness and corrosion-rate determination | Internal and thickness |
| CSA B51, cl.4 | Periodic inspection of boilers and pressure vessels by an authorised inspector, at intervals set by the jurisdiction | Header |
| ASME BPVC Section VIII | Pressure relief device capacity and set pressure requirements for the vessel it protects | Safety devices |
| PSSR 2000 reg.9 | Examination carried out in accordance with the governing written scheme, at intervals the scheme does not exceed | Outcome |
What it does not cover
- Pressure System Written Scheme, which defines what needs examining, how, and at what interval; this record is one examination carried out against it, not the scheme itself.
- Asset Condition Inspection, which assesses general asset condition against defined criteria rather than a statutory pressure examination.
- Vibration Analysis Record, which records vibration readings from rotating equipment.
- Thermographic Survey, which records infrared images of electrical panels, motors and bearings to find hot spots.
- Confined space entry permit, which must be raised separately whenever the internal examination requires entry into the vessel.
Global
Pressure Vessel Inspection requirements by country
The vessel's design code and its in-service inspection regime are usually set by different instruments, and which one governs the interval and the inspector's standing depends heavily on where the vessel sits.
State boiler and pressure vessel laws, generally incorporating the National Board Inspection Code
Inspection scope and interval are set at state level, with most jurisdictions adopting NBIC in-service inspection practice.
The applicable interval and required inspector qualification can differ by state even for an identical vessel, so the governing jurisdiction has to be checked, not assumed.
CSA B51, boiler, pressure vessel and pressure piping code
Periodic inspection by an authorised inspector is required, referenced into provincial regulation.
CSA B51 is a consensus standard, but provincial adoption makes its inspection requirements directly enforceable.
Pressure Systems Safety Regulations 2000, reg.9
Examination must be carried out in accordance with the vessel's written scheme, at the scheme's stated interval.
The scheme, not the design code, is the immediate legal reference for whether this examination was due and adequate.
How to complete it
How to complete a pressure vessel inspection, step by step
The template prompts an inspector through external examination, internal and thickness survey, and the safety devices. What decides whether the record is defensible is the judgement applied around those prompts.
A vessel can be correctly due for external examination and correctly not due for internal, and marking internal examination 'not due' is only honest when the scheme's own interval for it genuinely has not matured. Using 'not due' to avoid the cost and disruption of opening the vessel is the finding an auditor is looking for.
Minimum thickness found means little without the previous reading behind it. Corrosion rate per year and remaining life years are what turn a single measurement into a scheduling decision, and their absence is the most common way a technically passing vessel is quietly running out of margin.
Vessel fit for service has three states for a reason. A restricted outcome without a stated restriction in the record is not a restriction at all, it is a pass with a caveat nobody can act on, and it should be treated as incomplete until the restriction is written down.
An accredited inspection body, an insurer and an in-house competent person are not interchangeable, and the record should show which examined the vessel. Where the governing regime requires the higher standing, an in-house examination is not a lesser version of compliance, it is non-compliance with a passing result attached.
What auditors find
Most common pressure vessel inspection findings
A pressure vessel inspection record almost always exists and almost always shows a result. The findings are about what supports that result and what was quietly left out.
| Finding | Clause | What fixes it |
|---|---|---|
| Vessel marked fit for service with restrictions, but no restriction detail recorded. | ASME BPVC Section VIII | Require restriction detail whenever the outcome is anything other than an unrestricted pass. |
| Internal examination marked 'not due' with no record of when it last occurred. | National Board Inspection Code, Part 2 | Hold the date of the last internal examination against the vessel record so 'not due' can be checked, not assumed. |
| Minimum thickness recorded but corrosion rate and remaining life left blank. | National Board Inspection Code, Part 2 | Carry forward the previous reading and calculate the rate at the point the new reading is entered. |
| Relief valve tested, but its set pressure not checked against the vessel's design pressure. | ASME BPVC Section VIII | Record the design pressure alongside the set pressure so the two are compared at the point of test, not later. |
| Vessel examined by an in-house competent person where the governing regime requires an accredited body or insurer. | CSA B51, cl.4 | Check the required inspector standing against the vessel's classification before the examination is booked. |
| Internal examination performed with no confined space permit referenced. | Not applicable, general duty | Require a linked, current confined space permit before any internal examination proceeds. |
Case in point
Case in point: the vessel that passed three times before it failed
An air receiver at a distribution site was inspected annually for four years, external examination passing each time, internal examination marked 'not due' each time on the reasoning that the scheme allowed a longer interval for internal work, and thickness surveys recording a minimum thickness figure with the corrosion rate field left blank because nobody had entered a previous reading to calculate against.
On the fifth examination the internal survey finally came due, and found localised pitting corrosion well beyond what the recorded minimum thickness alone would have suggested, close to the vessel's minimum allowable thickness. Reconstructing four years of single readings after the fact showed a corrosion rate that, had it been calculated at any point, would have flagged the vessel for an earlier internal look. The fix was not a better inspector; it was requiring the rate to be calculated at every reading, so a trend existed before the vessel needed one.
The template
The template, field by field
The form exactly as it installs. Every field, option, score and conditional rule is editable, and the links to other templates come with it.
5 sections
- Reference
- MNT-036
- Archetype
- Inspection
- Record ID
- INSP-2026-000
- Scoring
- Pass or fail
- Direction
- High is good
- Singleton
- No
- Basis
- ASME BPVC, CSA B51
- Links
- Links Asset, Vendor
- Tags
- Maintenance, Statutory
- Sections
- 5
- Fields
- 53
- Follow up fields
- 6
- Repeating sections
- 0
- Links out
- 5
Header
20 fieldsInspection ID*
Auto sequence. Format INSP-2026-00000.
The record's own ID. Other templates point at this value.
Status*
Drives who this goes to next.
- Planned2 pts
- In progress2 pts
- Complete3 pts
- Deferred0 pts
- Open0 pts
- Closed3 pts
- Overdue0 pts
Date and Time*
Raised By*
Site*
Site ID*
Format SITE-000.
Links to FDN-001 Site ID
Area
The area within the site.
Exact Location
Drop a pin for anything hard to find.
Asset*
Asset ID*
Format AST-0000.
Links to FDN-002 Asset ID
Statutory And Non Negotiable
These inspections are required by law at set intervals. An expired certificate takes the vessel out of service, whatever its condition.
Vessel Type*
Design Pressure*
Design Code
Inspection Type*
External, internal, hydrostatic or thickness survey.
Statutory Interval Months*
Inspection Within Interval*
- Yes3 pts
- Overdue0 pts
Inspector*
Inspector Body*
- Accredited inspection body4 pts
- Insurer3 pts
- In house competent person2 pts
Inspector Competence Verified*
- Yes3 pts
- No0 pts
External examination
6 fieldsShell Condition*
- Good3 pts
- Minor corrosion1 pt
- Poor0 pts
Insulation And Cladding*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Supports And Foundations*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Nozzles And Connections*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Nameplate Legible*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
External Corrosion*
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Internal and thickness
8 fieldsInternal Examination Done*
Internal Corrosion
- Pass2 pts
- Partial1 pt
- Fail0 pts
- N/Aexcluded from denominator
Confined Space Permit ID
Links to SAF-049 Permit ID
Thickness Survey Done*
- Yes3 pts
- Not due3 pts
- No0 pts
Minimum Thickness Found
Above Minimum Allowable
- Yes, comfortably3 pts
- Yes, marginal1 pt
- No0 pts
Corrosion Rate Per Year
Remaining Life Years
Safety devices
5 fieldsRelief Valve Tested*
- Yes3 pts
- Not due3 pts
- No0 pts
Set Pressure Correct*
- Yes3 pts
- Adjusted2 pts
- No0 pts
Relief Discharge Safe*
- Yes3 pts
- Marginal1 pt
- No0 pts
Pressure Gauge Calibrated*
- Yes3 pts
- No0 pts
Safety Device Test ID
Links to MNT-062 Test ID
Outcome
14 fieldsVessel Fit For Service*
- Yes3 pts
- With restrictions1 pt
- No0 pts
Operating Restrictions Imposed*
- No3 pts
- Yes1 pt
Restriction Detail
Certificate Issued*
- Yes3 pts
- Not applicable3 pts
- No0 pts
Certificate Attached
Next Statutory Inspection Due*
Action Required*
Raise the action record, then enter its reference here.
- No2 pts
- Yes0 pts
Priority
- High0 pts
- Medium1 pt
- Low3 pts
CAPA ID
Format CAPA-2026-00000.
Links to FDN-014 CAPA ID
Action Owner
Inspector*
Signature*
Engineering Manager*
Second Signature*
MNT-036 · record IDs look like INSP-2026-000 · Links Asset, Vendor
Open in KnowellaRun it with agents
From a document you fill in to a programme that runs itself
The examination itself is the easy part to get right. What slips is the arithmetic that should follow it, and the link back to the scheme that set the interval in the first place.
Holds the vessel's inspection history against its asset record, carries thickness readings forward into a corrosion trend, and flags a due date before it is missed.
Checks each inspection against the governing written scheme's stated interval and inspector requirement for that vessel.
Verifies the accreditation of the inspection body or insurer before the examination is booked, and holds that evidence against the record.
Watches for a passing result with a blank corrosion rate or remaining life, and prompts for the calculation before the record is closed.
This template lives in KnowMaintain — asset maintenance. Work orders, planned maintenance, calibration, reliability and shutdowns.
Meet KnowMaintain→Glossary
Pressure Vessel Inspection definitions and key terms
- Minimum allowable thickness
- The lowest wall thickness at which the vessel can still safely hold its design pressure, calculated from the design code and compared against the reading found at each thickness survey.
- Corrosion rate
- The rate of thickness loss per year, derived from comparing successive thickness readings, used to project when a vessel will reach its minimum allowable thickness.
- Design pressure
- The maximum pressure the vessel is designed to withstand, against which a relief device's set pressure and the vessel's operating limits are both checked.
- Set pressure
- The pressure at which a relief device is designed to open, which must be verified at test and compared against the vessel's design pressure, not assumed correct because the valve is present.
- Fit for service, with restrictions
- An outcome permitting continued operation only under stated conditions, such as a reduced operating pressure, rather than an unrestricted pass.
FAQ
Frequently asked questions about pressure vessel inspection
What's the difference between this inspection and the written scheme?+
The scheme is the plan, setting which parts of the system need examining, how, and at what interval. This record is one examination, of one vessel, on one date, carried out against that plan. A strong inspection record can still sit on top of a scheme that no longer matches the plant.
Can internal examination be marked 'not due' indefinitely?+
Only while the governing scheme's own interval for internal examination genuinely has not matured. It should be checked against the date of the last internal examination each time, not treated as a default answer that avoids opening the vessel.
What does 'fit for service, with restrictions' actually require?+
A stated restriction, such as a reduced operating pressure or a shortened interval to the next examination. Without that detail recorded, a restricted outcome functions as an unrestricted pass with nothing anyone can act on.
Why does the inspector's body matter if the vessel passes either way?+
Because the governing regime often specifies who is competent to examine a given class of vessel. An in-house competent person passing a vessel that requires an accredited inspection body or insurer's examination has produced a result that is not compliant, whatever the finding says.
Should corrosion rate be calculated even when the vessel passes?+
Yes. A pass tells you the vessel is acceptable today. The corrosion rate is what tells you how much time remains before it is not, and it is the only way an inspection this year connects to the interval that should apply next time.
What happens if an internal examination needs vessel entry?+
A confined space entry permit is required separately, and should be referenced in the record before the internal examination proceeds. The inspection record itself does not grant entry authorisation.
Keep going
Related templates and programmes
Industries this is written for
Programmes this belongs to
Used together in Asset Inspection and Statutory Examination
Asset Condition Inspection
Assesses the general condition of an asset against defined criteria
Vibration Analysis Record
Records vibration readings taken from rotating equipment
Thermographic Survey
Records infrared images of electrical panels, motors and bearings to find hot spots
Oil Analysis Record
Records laboratory analysis of lubricating oil, covering wear metals, contamination and additive condition
Ultrasonic Inspection Record
Records ultrasonic readings used to find air leaks, electrical discharge and early bearing wear
Crane and Hoist Inspection
Checks cranes, hoists and their controls for wear, function and load rating
More in Asset Inspections
Asset Condition Inspection
Assesses the general condition of an asset against defined criteria
Vibration Analysis Record
Records vibration readings taken from rotating equipment
Thermographic Survey
Records infrared images of electrical panels, motors and bearings to find hot spots
Oil Analysis Record
Records laboratory analysis of lubricating oil, covering wear metals, contamination and additive condition
Ultrasonic Inspection Record
Records ultrasonic readings used to find air leaks, electrical discharge and early bearing wear
Crane and Hoist Inspection
Checks cranes, hoists and their controls for wear, function and load rating
Written and reviewed by
Siddarth Singh
Founder & Chief Executive Officer, Knowella
Certified Safety Professional and industrial and systems engineer with more than a decade inside food supply chain, freight and manufacturing operations. This page was written against the current text of the standards it cites, not against secondary summaries of them.
- Certified Safety Professional (CSP), Board of Certified Safety Professionals
- MBA, University of Chicago Booth School of Business
- MS and BS, The Ohio State University, Industrial and Systems Engineering
- Six Sigma Black Belt
Sources and last review. Reviewed 16 August 2026 against:
- ASME BPVC Section VIII, Division 1 — pressure vessels
- National Board Inspection Code, Part 2 — in-service inspection
- CSA B51 — boiler, pressure vessel and pressure piping code
- Pressure Systems Safety Regulations 2000, regulation 9 (UK)
This page is general guidance, not legal advice. Confirm requirements with your jurisdiction’s regulator.