STORAGE TANK INSPECTION SERVICES

When Your Tank Needs Inspecting

API 653 sets two inspection cycles for a tank in service. The external inspection happens at least every five years, or on a risk-based interval, and can be done with the tank running. The internal inspection is the bigger job: the tank comes out of service, is emptied and cleaned, and an inspector assesses the floor, the critical zone and the lower shell. How long you can leave between internals depends on the corrosion rate measured at the last inspection, so a tank holding clean product runs longer than one in aggressive service. We help owners set those intervals from real data rather than a fixed calendar.

Inspecting the Tank Floor

Most tanks fail from the bottom up. Water and sediment settle on the floor, and underside corrosion eats the plate from below where you cannot see it. That is why the floor gets the most attention during an internal inspection. We scan it with magnetic flux leakage (MFL) to find top and underside metal loss, take ultrasonic readings to confirm remaining thickness, and vacuum box the floor welds to prove they are leak-tight. The shell is checked for thinning and out-of-roundness, and settlement is measured around the base. Read together, these tell you whether the tank is fit to keep running and for how long.

API 653, API 650 and the Australian Standards

New tanks are built and tested to a construction code, almost always API 650 or the earlier API 12C. Once a tank is in service, API 653 governs its inspection, repair and reconstruction, and any repair has to take it back to the original construction code. In Australia those API codes work alongside AS 1692, which covers the construction of steel tanks for flammable and combustible liquids, and AS 1940, which covers how those liquids are stored and handled on site. Our reports reference the codes that apply to your tank and back the findings with engineering calculations, so they hold up with auditors and insurers.

What a Tank Integrity Assessment Tells You

An inspection produces findings. A tank integrity assessment turns those findings into decisions. The measured thickness readings are compared against the minimum required thickness for the shell course and the floor, corrosion rates are calculated from the change since the last inspection, and those rates set the remaining life of the tank and the date of the next internal. Where a course has thinned below what the standard allows, the assessment sets out the options: derate the tank, repair or replace the plate, or shorten the interval and monitor. Owners use that output to plan a shutdown budget rather than react to a leak.

NDT Methods We Use on Storage Tanks

Tank work draws on most of the NDT toolkit, and the method is chosen for the component being assessed:

• Magnetic flux leakage (MFL) — floor scanning to map top-surface and underside metal loss quickly across large areas.
• Ultrasonic testing (UT) — thickness readings on the shell, floor and roof, and corrosion mapping to confirm what MFL flags.
• Magnetic particle (MT) and liquid penetrant (PT) — surface and near-surface crack detection on welds, nozzles and repair areas.
• Vacuum box testing — proving floor and annular welds are leak-tight without filling the tank.
• Coating inspection — assessing the internal lining and external protective system, including holiday detection on linings.
• Visual inspection (VT) — the foundation of every API 653 external and internal inspection.
• Positive material identification (PMI) — confirming plate and repair materials match specification.

Where access is difficult, drone inspection covers roofs and upper shell courses without scaffolding, and hydrostatic testing is used to prove integrity after significant repair work.

Tanks and Vessels We Inspect

The same inspection disciplines apply across a range of assets. We assess vertical and horizontal bulk storage tanks holding fuel, chemical and process liquids, above and below ground. We inspect water storage tanks, where the concern is usually internal lining condition and floor corrosion rather than product compatibility. We also inspect pressure-rated vessels such as air receivers, which sit under a different regime again — those are covered on our pressure vessel inspection page, and our guide to air receiver inspection services explains what AS/NZS 3788 requires of them.

What You Receive

Every inspection produces a written report you can hand to an auditor, an insurer or a regulator. It records the scope and the codes applied, the thickness data with the locations it was taken from, photographs of the findings, the calculated corrosion rates and remaining life, any non-conformances with a recommended action, and the date the next inspection falls due. Where a repair is needed we set out what the standard requires so you can scope the work accurately before going to a contractor.

Where We Inspect

APEC is based in Newcastle and works throughout the Hunter and New South Wales, mobilising inspectors to sites across Australia for tank inspection and shutdown work. Tank inspections are usually planned around a shutdown window, so we schedule the crew and equipment to the outage rather than the other way around. If you have a shutdown coming up, talk to us early — internal inspections need the tank emptied and cleaned, and that sequencing is easier to arrange with notice.

Why Choose APEC Inspection for Storage Tank Inspection

APEC is a NATA-accredited inspection body. Our storage tank work is carried out by AINDT-certified technicians, with API 653 inspections signed off by a certified tank inspector. We assess vertical and horizontal tanks, above and below ground, and bring the NDT, ultrasonic testing, drone inspection and reporting together in one job. We mobilise from Newcastle and the Hunter across the country. To book an inspection or talk through an upcoming shutdown, request a quote.