API 650

welded flat-bottomed vertical storage tanks

API 650 | welded flat-bottomed vertical storage tanks

The API 650 is the American standard for welded flat-bottomed vertical storage tanks. This standard dictates tank design, manufacture, welding, inspection as well as installation requirements. This US standard is widely used for tanks designed to withstand low internal pressures for storage of typical products such as crude oil, petrol, chemicals and water. Gpi Tanks XL has extensive experience when it comes to API 650 tanks, varying from tanks built in the factory up to +/- 500m3, to tanks built on-location up to +/-15,000 m3.

Depending on the desired design and design conditions, these tanks are equipped with a conical roof or a doomed roof, with or without anchors and stiffening rings, such as wind girders and/or a top corner ring. Naturally, these tanks can be provided with a spiral staircase, a cage ladder or a stairway. In terms of material, a form of duplex is often chosen. Due to this material being stronger than normal austenitic stainless steel variants, thin walls can be employed, which ensure for a more rapid, higher quality and affordable tank.

stainless steel storage tanks

Gpi Tanks XL produces XL tanks both in its various factories and also directly on-location by means of our Coil Building system. Read more about this system here, or watch our Coil Building film.

We also produce tanks according to NEN-EN 14015, the European equivalent of API 650.

Specifications API 650

  • The American standard
  • Above-ground flat-bottomed tanks
  • Wind / Earthquake loads included
  • Test & Inspections included
  • Up to 15,000m3


  • Conical/ Domed / Removable roof
  • Double bottom / Cone up/down
  • Top corner ring/ Wind girders

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