API 650 / API 653 Tank Engineering
Design, Assessment & Compliance for Welded Steel Storage Tanks
Large welded steel storage tanks are critical assets across mining, industrial processing, agriculture, water and energy sectors. In Australia and internationally, the design, inspection and ongoing integrity of these tanks is governed primarily by API 650 and API 653.
Understanding how and when to apply each standard correctly is essential to managing safety, compliance and asset life.
What Are API650 and API653?
API 650 – Welded Steel Tanks for Oil Storage
API 650 governs the design and construction of new welded steel storage tanks, including:
Tank geometry and shell design
Roof types and structural components
Load cases (hydrostatic, wind, seismic)
Materials, welding and fabrication requirements
Foundation interaction and tolerances
It is widely adopted beyond oil storage, including for:
Water
Process liquids
Agricultural and industrial fluids
API 653 – Tank Inspection, Repair, Alteration & Reconstruction
API 653 applies to existing tanks and covers:
In-service inspections
Fitness-for-service assessments
Corrosion evaluation
Repairs, alterations and reconstruction
Remaining life assessment and continued operation
API 653 is often triggered when:
tanks are ageing,
corrosion is present,
tanks are modified,
or compliance documentation is required.
Why API Tank Engineering Matters
Storage tank failures can result in:
Environmental incidents
Safety risks
Operational downtime
Major financial and regulatory consequences
API 650 / 653 compliance ensures that tanks:
are structurally adequate,
meet recognised international standards,
and can be operated with confidence.
Engineering input is critical where:
tanks were built to older standards,
site conditions differ from original assumptions,
or modifications are proposed.
API 650 / API 653 Engineering Services
Trang Imagineering provides engineering support across the full lifecycle of storage tanks, including:
API 650 – New Tank Engineering
Design review and verification
Structural assessment of shells, roofs and components
Foundation and load assessment
Review of fabrication drawings and construction details
Engineering support during procurement or construction
API 653 – Existing Tank Assessment
Engineering review of inspection findings
Structural assessment of corroded shells and components
Remaining life calculations
Assessment of repairs, alterations or upgrades
Engineering documentation to support continued service
When Do You Need an Engineer?
Engineering involvement is essential when:
corrosion or deformation is identified,
shell thickness limits are approached,
loads or operating conditions change,
repairs or alterations are proposed,
or certification is required for regulators, insurers or asset owners.
Trang provides engineering-led assessments, ensuring decisions are technically defensible and practically implementable.
API Tank Engineering with Trang Imagineering
Trang Imagineering brings together:
mechanical and structural engineering expertise,
experience with Australian and international standards,
and a practical understanding of industrial assets.
Our API 650 / API 653 services support safe operation, compliance and informed asset management.
Talk to Trang Imagineering
If you require API650 or API653 engineering support, contact Trang Imagineering to discuss your tank asset, inspection findings or proposed works.