At 3P Tech Serv, we deliver specialist API tank engineering services — providing manufacturers, fabricators, and plant operators with accurate, code-compliant tank design and calculation packages built on deep experience with atmospheric and low-pressure storage equipment across oil and gas, petrochemical, and utility industries.
API 650 Tank Design Services
Our API 650 tank design services cover the complete mechanical design scope for welded steel atmospheric storage tanks in accordance with API Standard 650. We perform shell course thickness calculations using both the one-foot method and variable design point method, annular plate and bottom plate sizing, nozzle reinforcement calculations, and wind and seismic stability checks — producing a fully documented design package suitable for fabrication, client review, and third-party verification. Our API 650 services are applicable to tanks across a wide range of diameters, capacities, and stored product types.
API 620 Tank Calculation Services
Our API 620 tank calculation services address the design of large, welded, low-pressure storage tanks operating at internal pressures up to 15 psig — covering applications such as LNG storage, liquefied gas tanks, and other low-pressure process storage vessels. We perform full API 620 mechanical design calculations covering shell design, roof design, nozzle reinforcement, wind and seismic loading, and joint efficiency requirements — providing a complete, code-compliant calculation package that supports fabrication and regulatory submission.
Vertical Storage Tank Engineering
Our vertical storage tank engineering services cover the full mechanical engineering scope for cylindrical, vertical-axis atmospheric and low-pressure storage tanks across a broad range of sizes and service conditions. From initial capacity and geometry definition through to detailed shell, roof, and bottom plate design, our engineers apply API 650 and API 620 requirements as appropriate — ensuring that every aspect of the tank design is optimised for the stored product, operating conditions, and site environment. Our vertical storage tank engineering work is fully coordinated with foundation, nozzle, and accessories design to deliver a complete, consistent package.
Tank Roof Design Calculation
Tank roof design is a critical element of any storage tank engineering package, and our tank roof design calculation services address the full range of roof types used in API tank design — including cone roof, dome roof, and internal floating roof configurations. We perform roof plate thickness calculations, rafter and structural ring design, roof-to-shell junction checks, and vent and drain nozzle sizing — ensuring the roof design is structurally adequate, code-compliant, and consistent with the operating and maintenance requirements of the stored product. For floating roof tanks, we additionally assess pontoon buoyancy, seal arrangements, and drainage system requirements.
Tank Foundation Load Calculation
Our tank foundation load calculation services determine the loading imposed on the tank foundation by the storage tank under all relevant load conditions — including operating, hydrotest, wind, seismic, and empty conditions. We calculate base shear, overturning moment, and bearing pressure distributions in accordance with API requirements and applicable civil and structural codes, providing the foundation design team with the accurate, well-documented load data they need to size the ring beam, pad, or pile foundation correctly. Getting tank foundation loads right at the outset prevents costly foundation redesign and schedule delays during detailed engineering.
Atmospheric Tank Engineering Services
Our atmospheric tank engineering services cover the broader scope of design, analysis, and documentation for atmospheric storage tanks beyond standard API calculations — including tank appurtenances design, manway and nozzle schedule preparation, tank accessories specifications, corrosion allowance assessment, and material selection support. We also provide tank inspection support calculations, fitness-for-service assessments for existing tanks, and re-rating calculations for tanks being considered for a change of service — making our atmospheric tank engineering services a comprehensive resource for the full lifecycle of your storage tank assets.