API Std 650 is a comprehensive standard for the design, fabrication, welding, inspection, and erection of welded steel storage tanks used in the oil and gas industry. It covers tanks with internal pressures up to 2.5 PSI and temperatures ranging from -40°F to 500°F.

Engineers, fabricators, inspectors, and operators involved in the design, construction, and maintenance of welded storage tanks in the petroleum and chemical industries should use this standard.

The standard covers tank foundations, bottoms, shells, roofs, nozzles, and other structural elements. It provides guidelines for material selection, design calculations, fabrication processes, and inspection requirements.

API 650 applies to aboveground, cylindrical, non-refrigerated tanks with capacities greater than 119 gallons (450 liters). It covers tanks designed to store liquids such as crude oil, chemicals, and water at atmospheric pressure.

The standard incorporates rigorous safety measures, including specific design criteria, material specifications, and inspection requirements to ensure the structural integrity and operational safety of storage tanks.

The 13th edition includes enhanced safety measures, updated environmental considerations, integration of advanced inspection technologies, and improved welding practices. Specific changes can be found in the standard's "Summary of Changes" section.

API 650 provides comprehensive guidelines for seismic design, including methods for calculating seismic loads and designing tank components to withstand earthquake forces.

The standard mandates specific welding procedures, welder qualifications, and inspection requirements. It covers various welding processes, including Shielded Metal Arc Welding (SMAW) and Submerged Arc Welding (SAW).

API 650 provides guidelines for corrosion allowances, material selection, and protective coatings to ensure long-term tank integrity in corrosive environments.

The standard specifies various inspection and testing methods, including radiographic testing, ultrasonic testing, and hydrostatic testing, to ensure tank quality and integrity.

 API 650 is often used in conjunction with other standards, such as API 653 for tank inspection, repair, and reconstruction. It also references ASME standards for certain design and welding requirements.

The standard provides detailed calculations for determining minimum thicknesses of shell plates, bottom plates, and roof plates based on tank dimensions, design loads, and material properties.

The latest edition incorporates updated environmental considerations, including guidelines for secondary containment, leak detection, and emissions control.

API 650 provides specific guidelines for the design, reinforcement, and welding of nozzles and manways to ensure proper integration with the tank shell and maintain structural integrity.

API typically reviews and updates its standards every 5 years. However, addenda and errata may be issued between major revisions to address specific issues or clarifications.

API 650 provides guidelines for tank foundation design, including soil bearing capacity, settlement considerations, and concrete ring wall specifications. It also addresses requirements for anchoring systems in high wind or seismic zones.

The standard includes comprehensive requirements for both external and internal floating roof designs, covering aspects such as seal systems, roof support mechanisms, and drainage systems.

 API 650 outlines specific material requirements for various tank components, including allowable steel grades, toughness requirements, and material compatibility considerations for different operating conditions.

The standard provides guidelines for normal and emergency venting systems, including sizing calculations and design requirements to prevent over-pressurization or vacuum conditions.

API 650 specifies methods for calculating shell thickness, including the variable-design-point method and the one-foot method. It also addresses shell stability and wind girder requirements.

The standard provides guidelines for bottom plate thickness, lap joint design, and annular ring requirements. It also addresses considerations for leak detection systems and cathodic protection.

API 650 outlines procedures for hydrostatic testing, including fill rates, hold times, and acceptance criteria. It also provides alternatives for tanks that cannot be hydrostatically tested.

The standard provides guidelines for allowable settlement, including uniform and differential settlement limits. It also outlines methods for measuring and monitoring settlement during and after construction.

PI 650 covers design and installation requirements for various appurtenances, including shell manholes, roof manholes, stairways, platforms, and ladders.

The standard provides guidelines for insulation systems, including material selection, attachment methods, and considerations for corrosion under insulation (CUI).

API 650 specifies the information that must be included on tank nameplates, including design parameters, construction details, and API monogram (if applicable).

While API 653 is the primary standard for tank repair, API 650 provides some guidelines for modifications to existing tanks, including requirements for design calculations and welding procedures.

The standard outlines methods for calculating nozzle reinforcement areas and provides design guidelines for various nozzle configurations, including flush-type and pad-reinforced nozzles.

API 650 provides methods for calculating wind loads on tanks, including considerations for different roof types and wind girder requirements for tall tanks.

The standard outlines quality control measures for material receiving, fabrication, welding, and inspection processes. It also specifies documentation requirements for quality control records.