API 625-2010 pdf free download

API 625-2010 pdf free download.Tank Systems for Refrigerated Liquefied Gas Storage.
5.1 General 5.1.1 Three different main storage concepts are addressed in this standard. Sections 5.2, 5.3, and 5.4 define and describe each of these concepts. Diagrams of some implementations of these concepts are also provided. These diagrams are not meant to exclude other variations as long as they conform to the concept definitions. 5.1.2 Other storage concepts falling outside those defined herein may be possible but are not addressed in this standard. 5.1.3 In the diagrams provided, color is used to help illustrate the components that are designed for the low product temperatures (blue metal or gray concrete) and other components that are not so designed (red metal). 5.1.4 For all containment systems, liquid-tightness of the primary liquid container is required. Liquid is not permitted to accumulate outside the primary liquid container during normal operation. Tank systems where this is not assured would require consideration of issues such as liquid collection and disposal, potential cold spots, affect on tank venting, etc. This standard has not attempted to address these issues. 5.2 Single Containment Tank System 5.2.1 This system incorporates a liquid-tight container and a vapor-tight container. It can be a liquid and vapor-tight single-wall tank or a tank system comprised of an inner and outer container, designed and constructed so that only the inner container is required to be liquid-tight and contain the liquid product. 5.2.2 The outer container, if any, is primarily for the retention and protection of the insulation system from moisture (see Section 9) and may hold the product vapor pressure, but is not designed to contain the refrigerated liquid in the event of leakage from the inner container.
5.2.3 The primary liquid container shall be of low-temperature-metal or prestressed concrete. The outer tank (if any) shall be vapor-tight. It is normally made from carbon steel, and it is referenced in this standard in various contexts as the warm product vapor container or the purge gas container. 5.2.4 A single containment tank system is surrounded by a secondary containment (normally a dike wall) which is designed to retain liquid in the event of leakage (see C.2). 5.2.5 Some variants of single containment concepts having a single tank are depicted in Figure 5.1 and Figure 5.2. 5.2.6 Some variants of single containment concepts having inner and outer containers are depicted in Figure 5.3 and Figure 5.4.
5.3 Double Containment Tank System 5.3.1 This consists of a liquid and vapor tight primary tank system, which is itself a single containment tank system, built inside a liquid tight secondary liquid container. 5.3.2 The secondary liquid container is designed to hold all the liquid contents of the primary container in the event of leaks from the primary container, but it is not intended to contain or control any vapor resulting from product leakage from the primary container. The annular space between the primary container and the secondary container shall not be more than 6 m (20 ft). 5.3.3 The primary and secondary liquid containers shall be constructed either from metal or from concrete. 5.3.4 Variants of double containment concepts using single tanks and independent primary liquid and vapor containers are depicted in Figure 5.5 and Figure 5.6.
5.4 Full Containment Tank System 5.4.1 This consists of a liquid tight primary container and a liquid and vapor tight secondary container. Both are capable of independently containing the product stored. 5.4.2 The secondary container shall be capable of both containing the liquid product and controlling the vapor release in the event of product leakage from the primary liquid container. 5.4.3 The primary and secondary liquid containers shall be constructed either from metal or from concrete. 5.4.4 Vapor tightness of the tank system during normal service is required. Under inner tank leakage (emergency) conditions, tank system product losses due to container permeability are acceptable. 5.4.5 ACI 376 addresses various base-to-wall joint details. For certain low-temperature products, significant design issues arise at monolithically-connected outer tank base-to-wall joints due to the mechanical restraint offered by the base. To mitigate these issues, it is normal practice to include a secondary liquid containment bottom and thermal corner protection to protect and thermally isolate this monolithic area from the cold liquid and provide liquid tightness. Refer to ACI 376 for the design and detailing of such areas. The diagrams in this section approximately depict such details. Details of this subject are in 6.8.