API 650 – Welded Tanks for Oil Storage Gap Analysis
Systematically assess your welded storage tank design, fabrication, and erection programme against API 650 — covering materials selection and certification, tank design (shell, bottom, roofs), welding and inspection requirements, NDE of welds, hydrostatic and pneumatic testing, nozzles and accessories, foundations, seismic design, and API 650 appendix requirements for floating roofs and special applications.
Executive summary and section compliance overview for API 650 Welded Tanks for Oil Storage.
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🔴 Identified Gaps & Actions
ISO Xpert – Your API 650 Tank Quality Partner
Expert API 650 tank design and fabrication quality consulting — gap analysis, ITP review, welding procedure qualification support, NDE programme review, material certification review, and API 650 quality management for tank fabricators and operators worldwide. Headquartered in London.
ISO Xpert supports tank fabricators, EPC contractors, and terminal operators in achieving API 650 design, fabrication, and erection compliance. From materials certification review and shell design verification through welding procedure qualification, NDE programme development, hydrostatic test planning, and floating roof commissioning, our tank engineering specialists bring practical experience across the full API 650 scope for all tank types and sizes.
API 650API 653API Q1ISO 9001Tank Shell Design ReviewFloating Roof DesignWPS/PQR for Tank WeldingNDE Programme (RT/UT/MT/PT)Hydrostatic Test PlanningITP DevelopmentSeismic Design (App. E)Foundation DesignTraining Courses
📍 Contact
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ISO Xpert Ltd 71-75 Shelton Street, Covent Garden London WC2H 9JQ, UK
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Contact
ISO Xpert Ltd | 71-75 Shelton Street, London WC2H 9JQ | info@iso-xpert.com
Terms of Use
Last Updated: April 2025 | ISO Xpert Ltd
For legitimate internal API 650 tank fabrication quality assessment only. Results are indicative — not a substitute for a formal API 650 inspection. API 650 is the property of the American Petroleum Institute (API). ISO Xpert Ltd is not affiliated with API. Governed by the laws of England and Wales.
Contact
ISO Xpert Ltd | 71-75 Shelton Street, London WC2H 9JQ | info@iso-xpert.com
Common Questions
API 650 Welded Tanks for Oil Storage — Frequently Asked Questions
Authoritative answers about API 650 Welded Tanks for Oil Storage, inspection intervals, qualifications, RBI, and ISO Xpert consulting.
What does API 650 cover?
API 650 covers the material, design, fabrication, erection, and testing requirements for welded steel aboveground storage tanks for the petroleum and petrochemical industry. It applies to vertical, cylindrical, flat-bottomed tanks used to store crude oil, petroleum products, and other liquid products at or near atmospheric pressure. It covers tanks from small field tanks to very large refinery tanks exceeding 100m in diameter.
What are the main roof types covered by API 650?
API 650 covers three main roof configurations: (1) Fixed cone roofs — self-supporting or rafter-supported conical roofs welded to the shell; (2) External floating roofs (EFR) — open-top tanks with a floating roof (pontoon or double-deck) that rides on the product surface; and (3) Internal floating roofs (IFR) — fixed cone or dome roof tanks with an internal floating cover. Each has different design, welding, NDE, and operational requirements covered by the standard.
What NDE is required by API 650 for new tank construction?
API 650 requires: 100% visual examination of all welds; radiographic testing (RT) of shell vertical seam welds (the extent depends on tank height and shell plate thickness); vacuum box testing or ultrasonic testing of bottom plate welds; magnetic particle or liquid penetrant testing of nozzle welds; and a hydrostatic test (water fill to maximum design liquid level) after completion of all welding and NDE. The specific NDE requirements vary by shell course, material, and design conditions.
What is the difference between API 650 and API 653?
API 650 covers the design, fabrication, and erection of new welded steel storage tanks. API 653 covers the inspection, repair, alteration, and reconstruction of existing aboveground storage tanks originally built to API 650 or equivalent standards. API 650 is applied during tank construction; API 653 is applied during the in-service life of the tank, including periodic inspection, fitness-for-service evaluation, and major repairs.
Can ISO Xpert help with API 650 tank quality management?
Yes. ISO Xpert provides API 650 tank design and fabrication gap analysis, ITP (Inspection and Test Plan) review, welding procedure qualification support, NDE programme review, material certification review, and quality management system development for tank fabricators and operators. Contact us at info@iso-xpert.com or call +44 7853 109840.
