What is a pressure vessel annual inspection under AS 3788?

AS 3788 (Pressure Equipment - In-service Inspection) requires pressure vessels to be inspected at regular intervals to confirm they remain safe for continued operation. The annual inspection includes external visual examination for corrosion, bulging, dents and cracking, inspection of all nozzles and connections, pressure gauge verification, safety relief valve testing, drain valve check, nameplate and records verification, foundation and support inspection, weld inspection, ultrasonic thickness testing (if due), risk assessment review and compliance documentation. The inspection must be performed by a competent person as defined by AS 3788.

Who can perform a pressure vessel inspection?

Under AS 3788, a pressure vessel inspection must be performed by a competent person. A competent person is someone who has acquired, through training, qualification or experience (or a combination of these), the knowledge and skills to carry out the inspection. In most Australian jurisdictions, this means a qualified pressure equipment inspector, a mechanical engineer with relevant experience, or a person accredited by a recognised inspection body. The inspector must be independent of the operator for statutory inspections.

How often does a pressure vessel need to be inspected?

AS 3788 specifies inspection intervals based on a risk-based approach. As a general guide: annual external visual inspections, internal inspections every 3-6 years (depending on service conditions and risk assessment), and hydrostatic or proof tests as determined by the risk assessment. Higher-risk vessels (corrosive contents, high temperature, high pressure) may require more frequent inspection. The vessel owner and inspector must establish an inspection plan based on the specific vessel conditions.

What is ultrasonic thickness testing and when is it required?

Ultrasonic thickness (UT) testing is a non-destructive testing method that measures the remaining wall thickness of a pressure vessel using sound waves. A probe is placed on the vessel surface and the time taken for the sound pulse to reflect off the inner wall is converted to a thickness reading. UT testing is required when the inspection plan or risk assessment calls for it, typically when corrosion is suspected, when the vessel is approaching its calculated minimum wall thickness, or at intervals specified in the AS 3788 inspection plan.

What happens if a pressure vessel inspection is overdue or missed?

Operating a pressure vessel past its scheduled inspection date places the PCBU in breach of WHS Regulations 2011, Chapter 5, Part 5.1, which requires registered pressure equipment to be inspected per the documented inspection plan. Insurers may void pressure equipment coverage if the inspection register is not current, leaving the business exposed to the full cost of any incident. In the event of a vessel failure or workplace incident, an overdue inspection register would be a significant aggravating factor in any regulatory investigation. The vessel should be taken out of service until a competent person completes the overdue inspection and confirms it is safe to operate.

Is this pressure vessel annual inspection checklist free to use?

Yes. This pressure vessel annual inspection checklist is completely free to download and use. Open it in your browser and use Print then Save as PDF to create a hard copy for each vessel. No MapTrack account is required. If you want to automate inspection scheduling, receive alerts before inspections are due, store UT thickness readings digitally and maintain a complete compliance history for every vessel, MapTrack can do that. Book a demo to see how inspections and compliance tracking works.

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Free pressure vessel annual inspection checklist per AS 3788 (PDF-ready). Visual inspection, safety relief valve test and UT thickness. Download free.

Jarrod Milford

Commercial Director

Updated 3 May 2026

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What is a pressure vessel annual inspection (as 3788)?

A pressure vessel annual inspection checklist is a structured examination record used to confirm that a pressure vessel remains safe for continued operation in accordance with AS 3788:2006 (Pressure Equipment - In-service Inspection). The inspection covers the external condition of the vessel (corrosion, bulging, dents, cracking), all fittings and instruments (pressure gauge, safety relief valve, drain valve, sight glass), nameplate verification, operating records review, foundation and support condition, weld integrity, and compliance documentation. If the inspection schedule or risk assessment requires it, ultrasonic thickness (UT) testing is also performed to measure remaining wall thickness against the design minimum. The inspection must be carried out by a competent person as defined by AS 3788 and the results documented in the vessel inspection register.

Pressure vessel failures can be catastrophic, releasing stored energy with enough force to cause fatalities, severe injuries and extensive property damage. Under WHS Regulations 2011, Chapter 5, Part 5.1, pressure equipment must be registered with the state or territory regulator and inspected at intervals determined by a risk-based inspection plan. AS 1210:2010 governs the design and fabrication standard, while AS 3788:2006 governs the ongoing in-service inspection regime. Failure to maintain a current inspection register can result in regulatory enforcement action, insurance cover being voided and, in the event of an incident, significant personal liability for the PCBU. A completed annual inspection checklist provides the documented evidence that the vessel was examined by a competent person, that safety devices were tested and that any defects were identified and addressed.

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Benefits of using this pressure vessel annual inspection (as 3788)

Safety: pressure vessel failure can be catastrophic. Regular inspection identifies corrosion, cracking and wall thinning before they reach dangerous levels.
Regulatory compliance: AS 3788 compliance is a legal requirement in Australian jurisdictions. Documented inspections demonstrate compliance to WHS regulators and insurers.
Reduced downtime: identifying deterioration early allows planned repairs or replacement instead of emergency shutdowns.
Insurance: insurers require current inspection records for pressure equipment coverage. Lapsed inspections can void insurance cover.
Extended vessel life: a well-maintained and regularly inspected vessel can operate safely for decades. Neglected vessels may need early retirement.
Accurate records: a consistent inspection checklist builds a history of wall thickness measurements, defect findings and corrective actions that inform future risk assessments.

Benefits of digitising forms in MapTrack

When you digitise pressure vessel service procedures in MapTrack, you get:

Field users can easily scan a QR code to complete a form on mobile. Unlimited users.
Automatically get alerts when faults are identified.
Link every form digitally as a PDF to the relevant asset, location or person.
Receive a digital PDF copy with every submission to your email.
Ability to share forms digitally.
Build conditional logic (show or hide questions based on answers).
Take pictures or attach photos. Not possible with a paper-based form.
Electronic signatures.
Edit forms later without reprinting.
Restrict permissions (who can view, complete or approve).
Build forms with AI (describe what you need and MapTrack suggests the form).
Trigger work orders automatically when a fault is logged during an inspection.
Track service intervals by hours, kilometres or calendar date in one place.
Attach supplier invoices and parts receipts to each maintenance record.

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What to include in a pressure vessel annual inspection (as 3788)

This pressure vessel annual inspection (as 3788) covers 5 key areas:

External visual inspection: examine vessel body for corrosion, bulging, dents, cracks and paint condition; inspect nozzles, connections, insulation/lagging, foundations, supports, welds, bolted connections and flanges.
Fittings / instruments: verify pressure gauge calibration and range, test safety relief valve (pop test or bench test), inspect drain valve and sight glass/level gauge.
Nameplate / records: verify nameplate data matches records, review operating log for pressure/temperature excursions, verify compliance labels and inspection stickers.
NDT / thickness: ultrasonic thickness testing if due per inspection schedule or risk assessment.
Risk / compliance: review and update risk assessment, verify compliance documentation per AS 3788, update vessel inspection register.

How to use this pressure vessel annual inspection (as 3788)

Confirm the vessel is safe to approach. If the vessel is in service, coordinate with operations for safe access. Record vessel details: description, registration number, serial number, design pressure, contents and location.: Check with operations that the vessel is in a safe, stable condition before approaching. If the vessel is pressurised, ensure appropriate exclusion zones are maintained. Record the vessel description, state registration number, serial number, design pressure, MAWP, operating temperature, contents and physical location on the inspection form.
Perform the external visual inspection: examine the entire vessel surface for corrosion, bulging, dents, cracks and paint deterioration. Inspect all nozzles, connections, insulation and lagging.: Walk around the entire vessel and systematically inspect every visible surface. Look for general corrosion, localised pitting, bulging (indicating overpressure or creep), dents (indicating impact), cracking at weld toes and paint deterioration. Remove insulation covers at designated inspection points and check for corrosion under insulation (CUI). Inspect all nozzles and connections for leaks.
Check foundations and supports for corrosion, settlement or cracks. Inspect all welds visually (use dye penetrant testing if any concerns are identified). Inspect bolted connections and flanges for leaks and gasket condition.: Inspect saddle supports, skirts and legs for corrosion, cracking and settlement. Check anchor bolts for looseness. Visually inspect all accessible welds for cracking, porosity and undercut. If any visual indication is found, apply dye penetrant testing (DPT) to confirm. Check all flanged connections for leak staining and gasket condition.
Verify the pressure gauge is in calibration, readable and of the correct range. Test the safety relief valve by pop test to rated pressure (or remove for bench testing). Inspect the drain valve and sight glass/level gauge.: Check the pressure gauge calibration sticker is current and the dial range is appropriate (operating pressure should fall in the middle third of the scale). Test the safety relief valve by raising system pressure to the set point (pop test) or remove the valve for bench testing by a certified valve repair shop. Inspect the drain valve for operation and the sight glass for clarity and correct level indication.
Verify nameplate data is legible and matches records. Review the operating log for any pressure or temperature excursions. Verify compliance labels and inspection stickers are current.: Read the nameplate and confirm all data (manufacturer, serial number, MAWP, design temperature, test pressure) matches the vessel file records. Review the operating log or SCADA data for any pressure or temperature events that exceeded design limits since the last inspection. Check that the state inspection sticker and compliance labels are current.
If ultrasonic thickness testing is due (per inspection schedule or risk assessment), perform UT measurements at the specified test points and record readings.: Prepare the vessel surface at each designated test point by grinding to bare metal. Apply couplant gel and use a calibrated UT gauge to measure wall thickness at each point. Record readings and compare to the minimum calculated wall thickness for the vessel design conditions. Flag any readings approaching the minimum and schedule follow-up.
Review the risk assessment and update if there have been any changes to operating conditions, contents or environment. Complete all compliance documentation per AS 3788 and update the vessel inspection register.: Review the vessel risk assessment and fitness-for-service evaluation. Update if there have been changes to operating pressure, temperature, contents, corrosion rate or environmental conditions since the last assessment. Complete all required compliance documentation per AS 3788, including the inspection report and any recommendations for reduced operating limits or increased inspection frequency.
Record any defects, recommendations or corrective actions in the notes section. Set the next inspection date and sign off.: Document all findings, UT readings, valve test results and any defects. Specify corrective actions and timelines for each defect. Set the next annual inspection date based on the risk assessment and AS 3788 inspection plan. Obtain the inspector, vessel owner and competent person signatures.

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How often should you complete this service procedure?

Pressure vessel inspections follow a tiered schedule based on the risk assessment established under AS 3788:2006. At a minimum, operators should conduct routine operational checks daily or per shift, verifying that the pressure gauge reads within normal range, the safety relief valve is not leaking or weeping, the drain valve is clear and all visible fittings show no signs of leakage. These checks are typically performed by the equipment operator and recorded in an operating log.

Annual external visual inspections are the baseline formal requirement under AS 3788, covering the full vessel surface, fittings, supports, welds and compliance documentation. Internal inspections are typically performed every three to six years depending on service conditions, corrosion rate and the risk assessment outcome. Hydrostatic or proof tests are scheduled based on the risk assessment and may be required every six to twelve years. Higher-risk vessels, such as those containing corrosive media, operating at elevated temperatures or subject to cyclic loading, may require more frequent inspection at intervals determined by the competent inspector. WHS Regulations 2011, Chapter 5, Part 5.1 mandates that registered pressure equipment must be inspected at intervals specified in the inspection plan. The vessel owner and competent inspector must establish, maintain and review this plan as operating conditions change.

Frequently asked questions

Applicable regulatory standards

This template aligns with the following regulations and standards:

AS 1210:2010 - Pressure Vessels
AS 3788:2006 - Pressure Equipment - In-service Inspection
WHS Regulations 2011, Chapter 5, Part 5.1 - Registration and Inspection of Pressure Equipment
Safe Work Australia Code of Practice: Managing Risks of Plant in the Workplace

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