API std 650 pdf download.Welded Steel Tanks for Oil Storage
1.1 GENERAL 1.1.1 This standard covers material, design, fabrication, erection, and testing requirements for vertical, cylindrical, aboveground, closed- and open-top, welded steel storage tanks in various sizes and capacities for internal pressures approximating atmospheric pressure (internal pressures not exceeding the weight of the roof plates), but a higher internal pressure is permitted when additional requirements are met (see 1.1.10). This standard applies only to tanks whose entire bottom is uniformly supported and to tanks in nonrefrigerated service that have a maximum operating temperature of 90°C (200°F) (see 1.1.17). 1.1.2 This standard is designed to provide the petroleum industry with tanks of adequate safety and reasonable econ- omy for use in the storage of petroleum, petroleum products, and other liquid products commonly handled and stored by the various branches of the industry. This standard does not present or establish a fixed series of allowable tank sizes; instead, it is intended to permit the purchaser to select what- ever size tank may best meet his needs. This standard is intended to help purchasers and manufacturers in ordering, fabricating, and erecting tanks; it is not intended to prohibit purchasers and manufacturers from purchasing or fabricating tanks that meet specifications other than those contained in this standard.Note: A bullet (•) at the beginning of a paragraph indicates that there is an expressed decision or action required of the purchaser. The pur- chaser’s responsibility is not limited to these decisions or actions alone. When such decisions and actions are taken, they are to be specified in documents such as requisitions, change orders, data sheets, and drawings. 1.1.3 This standard has requirements given in two alternate systems of units. The requirements are similiar but not identi- cal. These minor differences are due to issues such as numeri- cal rounding and material supply. When applying the requirements of this standard to a given tank, the manufacturer shall either comply with all of the requirements given in SI units or shall comply with all of the requirements given in US Customary units. The selection of which set of requirements (SI or US Customary) shall apply to a given tank shall be by mutual agreement between the manufacturer and purchaser. 1.1.4 The appendices of this standard provide a number of design options requiring decisions by the purchaser, standard requirements, recommendations, and information that supple- ments the basic standard. An appendix becomes a require- ment only when the purchaser specifies an option covered by that appendix. See Table 1-1 for the status of each appendix.1.1.5 Appendix A provides alternative simplified design requirements for tanks where the stressed components, such as shell plates and reinforcing plates, are limited to a maxi- mum nominal thickness of 12.5 mm ( 1 / 2 in.), including any corrosion allowance, and to the minimum design metal tem- peratures stated in the appendix. 1.1.6 Appendix B provides recommendations for the design and construction of foundations for flat-bottom oil storage tanks. 1.1.7 Appendix C provides minimum requirements for pan-type, pontoon-type, and double-deck-type external float- ing roofs. 1.1.8 Appendix D provides requirements for submission of technical inquiries on this standard. 1.1.9 Appendix E provides minimum requirements for tanks subject to seismic loading. An alternative or supple- mental design may be mutually agreed upon by the manufac- turer and purchaser. 1.1.10 Appendix F provides requirements for the design of tanks subject to a small internal pressure. 1.1.11 Appendix G provides requirements for an optional aluminum dome roof. 1.1.12 Appendix H provides minimum requirements that apply to an internal floating roof in a tank with a fixed roof at the top of the tank shell. 1.1.13 Appendix I provides acceptable construction details that may be specified by the purchaser for design and con- struction of tank and foundation systems that provide leak detection and subgrade protection in the event of tank bottom leakage, and provides for tanks supported by grillage.