Steel Tank Design: API 650 vs EN 14015 Comparison Guide
API 650 (Welded Tanks for Oil Storage) is the American Petroleum Institute standard, dominant in North America and oil & gas worldwide. EN 14015 is the European standard for site-built flat-bottomed steel storage tanks. Both govern above-ground cylindrical tanks but differ significantly in philosophy and specific requirements.
Overview of the Two Standards
API 650 (Welded Tanks for Oil Storage) is the American Petroleum Institute standard, dominant in North America and oil & gas worldwide. EN 14015 is the European standard for site-built flat-bottomed steel storage tanks. Both govern above-ground cylindrical tanks but differ significantly in philosophy and specific requirements.
Design Method Differences
API 650 uses a one-foot design method for shell thickness calculation, with specific allowances for corrosion and wind/seismic loads. EN 14015 uses limit state design (partial safety factors) consistent with Eurocode methodology. API 650 shell thickness = (2.6×(H-1)×D×G)/(S×E), while EN 14015 uses γ factors for load and material. Results differ by 5-15% for the same tank geometry.
Material Specifications
API 650 permits ASTM A283 Gr.C, A36, A285 Gr.C, A516 Gr.60/70, A573, and API-grade steels. EN 14015 uses European steel grades: S235JR, S275JR, S355JR (EN 10025) plus specific requirements for notch toughness at design temperature. Cross-referencing between ASTM and EN grades is possible but requires careful verification of mechanical properties.
Inspection & Testing Requirements
API 650 requires radiographic examination of shell welds (minimum 250mm per vertical seam, 10% of circumferential seams). EN 14015 has similar volumetric testing but with different acceptance criteria based on consequence classification (Category A, B, C). Both require hydrostatic testing, but EN 14015 offers an alternative to full water testing for certain categories.
Foundation & Bottom Design
API 650 specifies concrete ringwall or slab foundations with specific settlement criteria. EN 14015 is more prescriptive about foundation design methodology and requires geotechnical assessment for tanks >10m diameter. Both standards address tank bottom plates but differ in minimum thickness requirements (API: 6mm min, EN: 5mm min for product contact).
Steel Plates for Tank Construction from CoreMetal
CoreMetal supplies tank-quality steel plates in API 650 grades (A283C, A36, A516-70) and EN 14015 grades (S235JR, S275JR, S355JR). Plates available in thickness 4-50mm, width up to 3000mm, length up to 12000mm. Mill test certificates provided per EN 10204 3.1. Contact Tracy for tank plate specifications and competitive pricing.
About Xi’an Coremetal Steel Co., Ltd.
CoreMetal is a leading Chinese steel supplier specializing in carbon steel, stainless steel, galvanized products, aluminum, and specialty alloys. With ISO 9001 certification and export experience to 60+ countries, we provide competitive pricing and reliable delivery for projects of all sizes. Contact Tracy at tracy@coremetalsteel.com or +86 18291910632 for inquiries.