1、API PUBLW327 94 0732270 0538378 OB1 m Aboveground Storage Tank Standards: A Tutorial HEALTH AND ENVIRONMENTAL AFFAIRS DEPARTMENT API PUBLICATION No. 327 SEPTEMBER 1994 Enviramrntal Partnmhp American Petroleum Institute 1220 L Street, Northwest Washington, D.C. 20005 11 One of the most significant lo
2、ng-term trends affecting the future vitality of the petroleum industry is the publics concerns about the environment. Recognizing this trend, API member companies have developed a positive, forward looking strategy called STEP: Strategies for Todays Environmental Partnership. This program aims to ad
3、dress public concerns by improving our industrys environmental, health and safety performance; documenting performance improvements; and communicating them to the public. The foundation of STEP is the API Environmental Mission and Guiding Environmental Principles. API ENVIRONMENTAL MISSION AND GUIDI
4、NG ENVIRONMENTAL PRINCIPLES The members of the American Petroleum Institute are dedicated to continuous efforts to improve the compatibility of our operations with the environment while economically developing energy resources and supplying high quality products and services to consumers. The member
5、s recognize the importance of efficiently meeting societys needs and our responsibility to work with the public, the government, and others to develop and to use natural resources in an environmentally sound manneiwhile protecting the health and safety of our employees and the public. To meet these
6、responsibilities, API members pledge to manage our businesses according to these principles: To recognize and to respond to community concerns about our raw materials, products and operations. To operate our plants and facilities, and to handle our raw materials and products in a manner that protect
7、s ths environment, and the safety and health of our employees and the public. To make safety, health and environmental considerations a priority in our planning, and our development of new products and processes. To advise promptly, appropriate officials, employees, customers and the public of infor
8、mation on significant industry-related safety, health and environmental hazards, and to recommend protective measures. To counsel customers, transporters and others in the safe use, transportation and disposal of our raw materials, products and waste materials. To economically develop and produce na
9、tural resources and to conserve those resources by using energy efficiently. To extend knowledge by conducting or supporting research on the safety, health and environmental effects of our raw materials, products, processes and waste materials. To commit to reduce overall emission and waste generati
10、on. To work with others to resolve problems created by handling and disposal of hazardous substances from our operations. To participate with government and others in creating responsible laws, regulations and standards to safeguard the community, workplace and environment. To promote these principl
11、es and practices by sharing experiences and offering assistance to others who produce, handle, use, transport or dispose of similar raw materials, petroleum products and wastes. Aboveground Storage Tank Standards: A Tutorial Health and Environmental Affairs Department API PUBLICATION NO. 327 SEPTEMB
12、ER 1994 American Petroleum Institute ACKNOWLEDGEMENTS This project was undertaken by the American Petroleum Institute (API) through the combined efforts of consultants, company representatives, and API staff. Will Carter of Chevron Oil Company, in conjunction with the API Storage lank Task Force, de
13、veloped the concept of the document. Rich Basile of Exxon, Phil Smith of Texaco, Bruce Roberts of Aramco, and Rick Nichols of Pennzoil made substantial contributions to the technical details. Dee Gavora of APls Health and Environmental Affairs Department served as Project Officer. Dana Marinacci, a
14、graduate student in public policy at Duke University, assisted in technical editing and production of this report. The API Refining Department and Office of General Counsel provided essential review of the technical information to facilitate completion of this document. FOREWORD API is not undertaki
15、ng to meet the duties of employers, manufacturers, or suppliers to warn and properly train and equip their employees, and others exposed, concerning health and safety risks and precautions, nor undertaking their obligations under local, state, or federal laws. Nothing contained in any API publicatio
16、ns is to be construed as granting any right, by implication or otherwise, for the manufacture, sale, or use of any method, apparatus, or product covered by letters patent. Neither should anything contained in the publication be construed as insuring anyone against liability for infringement of lette
17、rs patent. API makes no recommendations regarding the course of conduct that should be followed, and the reader is in no way bound to the findings of this study. The reader should exercise independent judgment that suits individual needs and must negotiate independently with the suppliers of any tec
18、hnology. API makes no promises, claims, or recommendations as to the site specific applicability, performance, or economics of any technology described herein. The reader is cautioned regarding the interpretation of any references to “costs“ or “cost effectiveness“ as these references may not be app
19、licable to hidher specific application. This tutorial may be used by anyone desiring to do so. Every effort has been made by the American Petroleum Institute to assure the accuracy and reliability of the material contained in it at the time in which it was written. However, API makes no representati
20、on, warranty, or guarantee in connection with the publications of this tutorial and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state or municipal regulation with which this tutorial may conflict, nor does
21、API undertake any duty to ensure its continued accuracy. PREFACE The American Petroleum Institute (API) sponsored the preparation of this document, “Aboveground Storage Tank Standards: A Tutorial,“ which presents procedures and examples to aid in understanding and complying with APls Recommended Pra
22、ctices (RPs), Standards (STDs), and Specifications (SPECS) regarding the prevention of leaks caused by bottom or shell corrosion, brittle fracture, and excessive settlement. It also shows how the API inspection and maintenance requirements influence the initial design of tanks. This tutorial is not
23、meant to be used by itself; rather it is meant to be used as an aid in understanding the relevant RPs, STDs, and SPECs and to be used in conjunction with those documents. API PUBL*327 94 m 0732290 0538384 385 TABLE OF CONTENTS 1 .O INTRODUCTION AND SCOPE 1 2.0 SUMMARY OF PROCEDURES . 3 FIGURE 2.1: L
24、OGIC DIAGRAM FOR TANK DESIGN 8, EVALUATION 4 FIGURE 2.2: LOGIC DIAGRAM FOR BOTTOM EVALUATION . 6 FIGURE 2.3: LOGIC DIAGRAM FOR SHELL EVALUATIONS 8 3.0 BASIC DATA REQUIREMENTS . 9 FIGURE 3.0 . HIGH PRIORITY DATA 9 4.0 BOTTOM SELECTION . 11 Case 1 . Basic Design Data for 150. O00 BARREL API STD 650 Ta
25、nk 13 Case 2 . Basic Design Data for IO. O00 BARREL Gasoline Storage Tank 13 Example 4.1 . Ground/Bottom Contact . 150. O00 Barrel Tank 15 Example 4.2 . Ground/Bottom Contact . IO. O00 Barrel Gasoline Tank 16 Example 4.3 . Ground/Bottom Contact . 500 Barrel Production Tank . 17 Example 4.4 . Cathodi
26、cally Protected Bottom . 18 Example 4.5 . Leak Detection/Containment System . 19 Example 4.6 . Leak Detection/Containment System . 20 Example 4.7 . Internal Bottom Lining . 21 Example 4.8 . Internal Bottom Lining and Cathodic Protection 23 Case 3 . Basic Design Data for 500 BARREL Production Fluid T
27、ank . 14 5.0 INSPECTION . 25 FlGURE5.1 . 25 FlGURE5.2 . 26 6.0 BOTTOM FLAWS 27 FlGURE6.1 . 27 Example 6.1 . Bottom Settlement 28 Example 6.2 . Bottom Corrosion . 29 7.0 SHELL EVALUATION . 31 Example 7.1 . Minimum Shell or Ring Thickness . 31 Example 7.2 . Risk of Brittle Fracture . 32 AppendixA 35 A
28、ppendixB 39 AppendixC 43 AppendixD 47 AppendixE 55 AppendixF 63 AppendixG . 69 AppendixH 75 1.0 INTRODUCTION AND SCOPE 1.1 Introduction This document is published to help owner/operators of aboveground storage tanks (ASTs) maintain ASTs in an environmentally safe manner. API maintains several compre
29、hensive documents that address the design, fabrication, operation, inspection, and maintenance of ASTs. Based on the combined industry experience of tank designers, fabricators and owners, the API documents provide guidelines designed to minimize the risk of an environmental hazard caused by spills
30、or leaks. This tutorial presents a set of procedures and examples to aid in understanding and complying with API Recommended Practices (RPs), Specifications (SPECS) and Standards (STDs). 1.2 Scope The procedures contained in this tutorial address the prevention of leaks or catastrophic loss caused b
31、y corrosion of the tank bottom or shell, brittle fracture, and excessive settlement. And, most importantly, they show how the API inspection and maintenance documents influence the design of new or proposed tanks. This document is applicable to ASTs fabricated and/or maintained per the following sta
32、ndards: API SPEC 12B: API SPEC 12D: API SPEC 12F: API RP 12R1: API STD 650: API RP 651: API RP 652: API STD 653: Bolted Tanks for Storage of Production Liquids; Field Welded Tanks for Storage of Production Liquids; Shop Welded Tanks for Storage of Production Liquids; Setting, Maintenance, Operation,
33、 and Repair of Tanks in Production Service; Welded Steel Tanks for Oil Storage; Cathodic Protection of Aboveground Storage Tanks; Lining of Aboveground Petroleum Storage Tank Bottoms; Tank Inspection, Repair, Alteration, and Reconstruction. Application of the principles discussed in this tutorial to
34、 ASTs constructed to differing design criteria should be based on sound engineering judgements. This tutorial does not attempt to address additional rules and requirements that may be imposed by individual jurisdictions or states. I 2.0 SUMMARY OF PROCEDURES Figures 2.1, 2.2, and 2.3 are logic diagr
35、ams that provide a picture of the process used to minimize the risk of bottom or shell leaks from a proposed or existing tank. The discussion below briefly summarizes each diagram. 2.1 Proposed Tanks Figure 2.1 shows that the first decision relates to whether the tank is proposed or existing. While
36、the evaluation steps for a proposed or existing tank may be similar or in some cases identical, the results for a proposed tank provide options that influence design and construction decisions. Results associated with existing tanks may lead to repairs or a change of service conditions. If the tank
37、is proposed, then how does one comply with the API in-service AST inspection STD 653 and RP 12R1? (Note: These two documents will be referred to collectively as the API Standard). The logic diagram shows that the API Standard does influence the proposed design, especially in the important area of bo
38、ttom selection. If the tank is proposed, then one proceeds along the left side of Figure 2.1. After compiling basic data, the major benefit of the procedure is to provide tank bottom design options. This is an important step. If the owner/operator expects a reasonable onstream time, then the influen
39、ce of cathodic protection, leak detection, linings, etc., on inspection frequency must be explored. Tank bottom design is based on standards and engineering and economic data. The last box on Figure 2.1 provides a method for selecting a bottom design when several configurations satisfy the API Stand
40、ard. 2.2 Existing Tanks The right side of Figure 2.1 shows that the evaluation process for existing tanks is separated into three paths. Tank Bottom and Shell are the two paths which are addressed in this tutorial, and are shown in Figures 2.2 and 2.3, respectively. The decision path for evaluation
41、of a tank roof is beyond the scope of this tutorial. However, Figure 2.1 shows that existing tank roofs may be evaluated per the methods in the API Standard and repaired, altered, or returned to service. 3 FIGURE 2.1: LOGIC DIAGRAM FOR TANK DESIGN StP, = O if the tank bottom is internally lined (see
42、 API RP 652). maximum underside pitting rate, in inches per year; UP, = O if tank bottom is cathodically protected (see API RP 651). maximum rate of general corrosion, in inches per year. anticipated in-service period of operation, in years. 4.2 API 12 Series Production Tanks Production tanks are us
43、ually much smaller than API Standard 650 tanks and their operating conditions and objectives are often substantially different than those used in refining, marketing, and transportation operations. These and other unique characteristics are reflected in API RP 12R1. API RP 12R1 requires two types of
44、 scheduled internal examinations, the scheduled Internal Condition Examination (conducted by appropriate field personnel) and the scheduled Internal Inspection (conducted by a qualified inspector). At a minimum, a scheduled Internal Condition Examination should be made for the following events: When
45、 a tank is cleaned for normal operational requirements; When there is a change in tank location; When the service is changed more than five years after an Internal Inspection; or When the tank is entered for any type of maintenance or modification. Scheduled Internal Inspections should be based on t
46、he corrosion rate life of the tank as given by: (furrent - trninimurn) Corrosion Rate Life (yeam) = _-_ corrosion rate (incheslyear) Where tcurrent is the measured thickness of the bottom plate and where tmlnlmum, for the Critical Annular Ring area, is 0.50 times t, of the shell or a minimum of 0.06
47、2 inch. For small production tanks, the calculation is based on the structural consideration of the annular ring. At a minimum, inspections should occur at the beginning of the last predicted life when a minimum required plate thickness is still in place. quarter of the 12 4.3 Case Studies Three cas
48、es are shown below, with basic design data provided for each. These cases are used as the basis for the examples in this section. Case I - Basic Design Data for 150,000 BARREL API STD 650 Tank A 150,000 barrel API STD 650 tank is in the design stage. The design data are: Capacity 150,000 barrels Soi
49、l Condition Firm, little settlement and good drainage Stored Product Petroleum crude Frequency of Internal General Corrosion 3 mPY Internal Bottom Pitting 20 mpy External Bottom Pitting 25 mpy bare steel Inspection 10 years 3 mpy on concrete slab 3 mpy if cathodically protected Design Life 40 years Size Height 48 feet, Diameter 150 feet Bottom Plates 0.25 inch Case 2 - Basic Design Data for 10,000 BARREL Gasoline Storage Tank A 10,000 barrel gasoline storage tank is proposed. The underside corrosion is based on replacing the native soil b
