IS 1521 covers large vertical cylindrical welded steel tanks for petroleum storage — the Indian equivalent of API 650. Used at refineries, fuel depots, and oil terminals for storing crude oil, petrol, diesel, and other petroleum products. Capacities range from 200 kL to 50,000 kL.
Specification for vertical cylindrical welded steel tanks for above-ground storage of petroleum products covering design, fabrication, testing, and foundations.
Key Values
Capacity range200 kL to 50,000 kL
Shell materialIS 2062 E250/E350
Roof typesFixed cone, floating, dome
Practical Notes
! IS 1521 is the Indian equivalent of API 650 — most Indian oil companies accept either standard.
! Floating roof tanks are mandatory for volatile products (petrol, naphtha) to minimize evaporation losses.
! Shell courses get thicker towards the bottom — bottom course carries the highest hydrostatic pressure.
! Settlement monitoring during hydrostatic test is critical — differential settlement >25mm is cause for concern.