API 650
Welded Tanks for Oil Storage
API 650 is the international standard for the design, fabrication, erection, inspection, and testing of welded atmospheric storage tanks for oil and refined petroleum products. The standard covers cone roof tanks, internal floating roof tanks, external floating roof tanks, and double-deck floating roof tanks at refineries, oil marketing terminals, and petrochemical plants. Every petroleum storage tank in EPC scope is designed to API 650.
API 650 (Welded Tanks for Oil Storage) is the foundational atmospheric storage tank design standard published by the American Petroleum Institute. The standard addresses tank design (wall thickness, head design, foundation requirements), materials (carbon steel grades, stainless steel, aluminium), fabrication (welding per ASME Section IX, NDE per Section V), erection, inspection (during erection plus periodic in-service inspection per API 653), and testing (hydrostatic test, magnetic particle examination, vacuum box test). API 650 tanks operate at atmospheric pressure (design pressure not exceeding 2.5 psig) and store petroleum products from crude oil through finished products including chemicals. See the CCOE Tank Farm standard for the Indian regulatory overlay.
API 650 tank types
API 650 covers cone roof tanks (fixed roof, typically for diesel, kerosene, fuel oil), internal floating roof tanks (cone roof with internal floating cover for evaporation control, typically for gasoline, naphtha, jet fuel), external floating roof tanks (no fixed roof, floating roof rises with product level, for high-volatility products), and double-deck floating roof tanks (heavier construction for fire-water service). Each tank type has specific design, fabrication, and inspection requirements.
Material and corrosion control
API 650 allows carbon steel (SA-283 grade C, SA-285 grade C, SA-516 grade 70), stainless steel (SA-240 304 / 316L), and aluminium. Corrosion allowance per service: typically 1.5 mm for sweet service, 3 mm for sour service, more for high-corrosion service. Cathodic protection on the underside of the bottom plate is mandatory. Internal coating selection per product service.
API 650 vs API 620 vs API 653
API 650 covers atmospheric storage tanks (≤ 2.5 psig design pressure). API 620 covers low-pressure tanks (2.5 to 15 psig design pressure) used for LNG, ethanol, and specialty products. API 653 covers inspection, repair, alteration, and reconstruction of existing API 650 tanks in service. EPC projects use API 650 for greenfield tanks; operating plants use API 653 for periodic inspection.
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Indian PSU refineries operate 20-100 atmospheric tanks per complex covering crude, intermediate products, and finished products. Each tank is designed to API 650 with IBR overlay where applicable.
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Greenfield refinery and petrochemical EPC projects design tank farms to API 650 from initial plot plan stage. API 650 wall thickness, foundation, and corrosion allowance drive the procurement and construction scope.
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Oil marketing depots (Indian Oil, Bharat Petroleum, Hindustan Petroleum) operate API 650 tanks across 30-200 depots per company under continuous API 653 inspection cycles.
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Brownfield revamp projects produce fresh API 650 tanks for capacity expansion. Existing tanks operate under API 653 inspection and may require repair, alteration, or reconstruction per API 653 procedures.
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EPC contractors producing tank deliverables for Indian PSU clients combine API 650 design with IBR-scoped piping per ASME B31.3, OISD 118 inter-distance per Petroleum Rules 2002, and CCOE Form XIV licence packaging.
Pathnovo's Material Data Report automation compiles API 650 tank handover packs including design calculation, mill test reports, NDE certificates, hydrostatic test certificate, and Authorised Inspector sign-off. Combined with MTR traceability and the Indian EPC compliance bundle, the workflow produces inspector-ready CCOE Form XIV documentation packs for petroleum storage installations.
What does API 650 cover?
API 650 is the international standard for welded atmospheric storage tanks at refineries, oil marketing terminals, and petrochemical plants. The standard covers cone roof, internal floating roof, external floating roof, and double-deck floating roof tanks operating at atmospheric pressure (≤ 2.5 psig design pressure).
What is the difference between API 650 and API 653?
API 650 covers design and fabrication of new welded atmospheric storage tanks. API 653 covers inspection, repair, alteration, and reconstruction of existing API 650 tanks in service. EPC projects use API 650 for greenfield tanks; operating plants use API 653 for periodic inspection and integrity management.
Which materials does API 650 allow?
API 650 allows carbon steel (SA-283 grade C, SA-285 grade C, SA-516 grade 70), stainless steel (SA-240 304 and 316L), and aluminium. Material selection depends on service (crude vs finished product), corrosion allowance per product, and temperature regime. Cathodic protection on bottom plate underside is mandatory.
Which tank type is used for gasoline storage?
Gasoline and high-volatility petroleum products (naphtha, jet fuel) typically use internal floating roof tanks (IFR) per API 650. The internal floating roof reduces evaporation losses, vapour pressure exposure, and fire risk. Higher-volatility products use external floating roof tanks (EFR).
Does India use API 650 for tanks?
Yes. API 650 is the foundational atmospheric storage tank standard used in Indian refineries, petrochemical plants, oil marketing terminals, and depots alongside IS / BIS / IBR codes. Indian PSU refineries and oil marketing networks reference API 650 directly in tank design specifications.
Material Data Report Automation
API 650 tank handover pack automation.
MTR Traceability Software
Mill test reports for API 650 tank materials.
CCOE Tank Farm Standard
Indian regulatory overlay for API 650 tanks.
OISD 118 Standard
Tank farm inter-distance and HAZOP standard.
ASME Section VIII
Pressure vessel code for higher-pressure storage above API 650 scope.
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