1、 THE ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION , GUIDANCE TO OWNERS ON DEMOLITION OF VERTICAL CYLINDRICAL STEEL STORAGE TANKS AND STORAGE SPHERES SECOND EDITION PUBLICATION No 154 : 2002 THE ENGINEERING EQUIPMENT AND MATERIALS USERS ASSOCIATION The Engineering Equipment and Materials Use
2、rs Association-EEMUA-was formed in 1983 by the Amalgamation of the Oil Companies Materials Association (OCMA) and the Engineering Equipment Users Association (EEUA). It is an organisation of substantial purchasers and users of engineering products, whose members include leading national and multinat
3、ional companies in the petroleum, gas, chemical and energy industries, and engineering contractors that provide services to those companies. A list of Full and Associate Members (the latter being limited to membership of three technical committees) is given below. EEMUA is concerned with the design,
4、 installation, operation and maintenance of the engineering plant used by members in pursuing their business activities. The Association aims to reduce members costs by providing the opportunity for them to share resources and expertise in order to keep abreast of technological developments and impr
5、ove the effectiveness and efficiency of their engineering activities. EEMUA supports the British Standards Institution, works with other institutions, associations, government departments, regulatory authorities and the Confederation of British Industry, and is also actively involved with other stan
6、dards-making bodies, both national and international, such as the American Petroleum Institute. Work, which is carried out in-house by members alone or with the help of other organisations, may lead to the production of Association publications. These are prepared primarily for members use, but are
7、usually offered for sale and thus for more general use. Such publications may also be submitted, normally through the British Standards Institution, as bases for appropriate national, European or international standards. A list of current EEMUA publications which may be purchased from the Associatio
8、n is given at the end of this publication. Full Members Associate Members ABB Process Industries UK Associated Octel BP Conoco Dow Corning ExxonMobil Foster Wheeler Energy lnnogy (was National Power) Lindsey Oil Refinery PowerGen Shell Transco/ Advantica* TXU Energi (was Eastern Generation) AEA Tech
9、nology AstraZeneca BASF Chevron Texaco D it is therefore essential, for the owner/ user, from here on referred to as the owner (see 1.3 below), and the contractor to carry out a detailed inspection prior to the start of demolition. The type and strength of the structure and the site conditions may i
10、nfluence the preferred demolition method. Various alternatives are possible, and each will have its advantages depending on the limitations imposed by the location, etc. In the last thirty years many vertical steel storage tanks have been demolished worldwide. In some cases the owners of such tanks
11、entered into contracts with demolition contractors without sufficient knowledge of the problems involved. As a consequence, a number of serious and sometimes fatal accidents have occurred. The causes have included inadequate contract specification, insufficient inspection and supervision, shortcomin
12、gs in the site safety arrangements and unsafe demolition procedures. For the safety of operatives, remote demolition is preferred-provided other considerations, such as restricted access, do not preclude that option. These guidelines are written particularly for the owners of storage tanks and spher
13、es to assist them in evaluating the acceptability of the methods being proposed for demolition work, in order to ensure that it is carried out in a satisfactory, safe and environmentally acceptable manner. Scope 1.2.1 General This document describes the various phases of the demolition work and the
14、responsibilities of the various parties involved in the process, and highlights some of the pitfalls that may be encountered, for the following types of structures: 0 vertical cylindrical, non-refrigerated storage tanks built in accordance with BS 2654, API 650 or a similar code vertical cylindrical
15、, refrigerated storage tanks built in accordance with BS 7777, API 620 or a similar code column-supported LPG or ammonia spheres built in accordance with BS (now PD) 5500, ASME Section VIII, Division 1 or 2, or other national pressure vessel codes. Although some information is included on demolition
16、 procedures, this document does not provide a comprehensive list of all methods that may be proposed by demolition contractors. This document also assumes that the tank material will not be reused to construct a new tank. 3 1.2.2 Refrigerated Storage Tanks While at present there is no immediate indu
17、stry need for recommendations on the demolition of refrigerated storage tanks, a section has nevertheless been included covering this type of tank (Section 9). 1.3 Terminology In this publication the term owner is used for the party having the ultimate responsibility for the safe demolition of the t
18、ank. This may be the party having legal ownership of the tank, or a second party to whom such responsibility is assigned. To avoid subsequent difficulties, it is essential that should a second party be assigned the responsibility, this be clarified and understood, by means of a formal agreement if n
19、ecessary, prior to detailed (demolition) contract discussions and the commencement of any site work. In the UK, tank demolition work will be governed by The Construction (Design and Management)-CDM-Regulations, discussed in the next section. The CDM Regulations use the term client instead of owner,
20、and the second party (where employed) is referred to as the clients agent. It should also be noted that the term construction, as used in the various UK statutory regulations, includes demolition work. 4 2 2.1 2.2 RESPONSIBILITIES OF OWNER AND CONTRACTOR General The responsibilities and obligations
21、of owner and contractor should be explicitly set out in the contract to ensure a clear understanding of those particulars by all the parties involved. The contract must be consistent with legal requirements. For example, in the UK The Construction (Design and Management) Regulations 1994 will apply.
22、 Those regulations require the Client (owner) to appoint both a Planning Supervisor and a Principal Contractor, and specify the responsibilities of each of the three parties. For example, the Planning Supervisor has to ensure that a pre-tender stage health and safety plan is prepared. The Principal
23、Contractor is then required to develop the plan before work starts on site, and to keep it up to date throughout the construction phase. The Health and Safety Executive (HSE) publishes information sheets giving guidance on the CDM Regulations: CIS 39 to 44. Other regulations which may be applicable
24、are the Construction (Health, Safety and Welfare) Regulations 1996, The Management of Health and Safety at Work Regulations 1999, and the Environmental Protection Act 1990. 0 w n e rs Res pons i b i I it ies As stated above, the owner has the responsibility to appoint the demolition contractor. He m
25、ust satisfy himself that the contractor is capable of providing the supervision, labour and equipment consistent with the needs of the task, and conducting the operation in accordance with good demolition practice. Documents such as BS 6187 Code of Practice for Demolition and the HSE leaflet Guidanc
26、e on Health and Safety in Demolition provide basic guidance in this regard. In addition, the owner should ensure that the following are observed/ carried out: That the agreed demolition procedure takes account of all the requirements set out in this document as well as recognising the special requir
27、ements of the individual tank, its location, and local conditions and constraints. This includes establishing the boundaries of the site within which the demolition contractor will work. That all relevant site details as well as design and operating data for the tank to be demolished are made availa
28、ble prior to the development of the demolition procedure. That the tank is safe to work on, free from toxic/ flammable vapours and residues, before it is handed over to the demolition contractor. The decommissioning process should be adequately documented, and all relevant documentation made availab
29、le to the contractor prior to the commencement of the work. That appropriate supervision is provided throughout the demolition period. A project engineer should have overall responsibility for all technical aspects, and a safety inspector provide the detailed day-to-day safety checks. These should i
30、nclude checking the contractors compliance with the agreed procedures, gas tests in and around the tank, scrutiny of hot work procedures and general safety measures. That arrangements are made in advance for the safe disposal of all material from the demolished tank. Legislation concerning the remov
31、al of poisonous or contaminated materials from the site must be carefully followed. The importance of the correct removal and disposal of lead contaminated materials is emphasised here: these should never be sold for reuse. 5 0 That a record of the demolition proceedings is kept for future reference
32、 and to facilitate investigations in the event of an accident. 0 A permit-to-work procedure will usually be required for demolition of storage tanks, particularly to ensure the essential checking of the tank and its connected services prior to the commencement of the work or parts of the work. 2.3 C
33、ontractors Responsibilities The Contractor will be required to establish and observe safe working practices and to comply with the relevant site instructions. He should prepare a demolition procedure defining the approach to be used, taking full account of all aspects of the site: access, condition,
34、 and any limitations or constraints imposed by local regulations. The safety of equipment used should be regularly checked, and all necessary maintenance carried out before use. The approved safety equipment (e.g. safety clothing, harnesses, lifelines, breathing equipment, helmets, etc.) should norm
35、ally be provided by the contractor and kept in a secure and dry place when not in use. Work should not be undertaken until all certificates and permits have been read, authorised and accepted. The contractors method statement should include all necessary details (see 6.3). 6 3 TYPES OF STORAGE VESSE
36、L 3.1 Storage Tanks (Non-Refrigerated) 3.1 .I Types of Storage Tank Vertical cylindrical steel storage tanks can be divided into two main groups: fixed roof tanks and floating roof tanks. The main structural hazard associated with tank demolition concerns the roof and the roof supporting structure.
37、It is therefore important to recognise the different designs that may be found in practice. 3.1.2 Fixed Roof Tanks Fixed roofs may be flat, conical or dome shaped (spherical). Generally, tanks less than 12 m diameter have either: Tanks over 12 m diameter have either: 0 0 It should be noted that fixe
38、d roof tanks used for the storage of motor spirit or other volatile products are often equipped with an internal floating cover. a self supporting membrane type roof without framing a supported roof with a simple rafter type framing. a supported roof with a truss type framing supported off the shell
39、 a supported roof with a column-supported framing. 3.1.3 Floating Roof Tanks The following types of floating roof are commonly used: 0 pontoon type floating roof double deck floating roof 0 0 buoy type floating roof. pontoon type roof with radial stiffeners 3.2 Refrigerated Liquefied Gas Storage Tan
40、ks First generation tanks, built prior to 1975, are frequently classified as single containment tanks. The tanks may have a single or a double wall. The tanks were usually designed to BS 4741, BS 5387 or API 620, Appendices Q and R. Single-wall tanks with external insulation were normally used for t
41、he storage of butane, ammonia, propane and propylene (see Figures 9 and IO). Double-wall tanks were normally used for the storage of ethane, ethylene and LNG (see Figures 11 and 12). The outer wall of a double-wall tank is not designed to contain the refrigerated liquid, but provides the vapour barr
42、ier for the insulation around the inner tank. The outer wall is rather thin. Double-wall tanks without a suspended deck were provided with an inner and outer roof so that the inner tank contained the refrigerated liquid and the product vapour. The space between inner and outer tank was filled with a
43、n inert gas (nitrogen) under a small positive pressure. Later, double-wall tanks were provided with a suspended deck, supporting the roof insulation, and an open top inner tank. In double-wall tanks with a suspended deck, the product vapour is contained within the outer tank. 7 Second generation ref
44、rigerated tanks were built after 1975. These tanks are classified as either double and full containment tanks. Double and full containment tanks often include a concrete wall with steel liner and concrete or steel roof, surrounding an open- top inner tank. Such tanks are designed to BS 7777. Refrige
45、rated storage tanks may be constructed on an elevated concrete structure to allow free ventilation under the tank foundation. They may also be placed directly on a foundation at ground level, in which case bottom-heating elements are used to prevent frost heave in the soil under the tank. 3.3 Column
46、-Supported Spheres Column-supported spheres are used for the storage of liquefied gases under pressure. The shell and the columns are designed to carry the dead weight, the weight of the product or test water and any additional forces resulting from internal pressure, wind or seismic loads. Column-s
47、upported spheres are stable structures as long as all the columns and column bracing are in sound condition. If a single column fails, the entire structure is likely to collapse and topple (see Section IO). 8 I 4 4.1 4.2 METHODS OF DEMOLITION Demolition Alternatives There are two demolition alternat
48、ives: on site and off site, of which the former is more common. On-site demolition can be further divided into: demolition on a decommissioned site 0 demolition on an operating site with reasonable access and working area demolition on an operating site with restricted access. While this document de
49、als mainly with on-site demolition, many of the principles apply also to off-site demolition. The latter assumes that the tank can be removed in one piece, and the feasibility of this need to be checked before choosing this alternative. Demolition work can be carried out either cold or hot. Cold cutting employs some form of spark-free cutting device such as water cutting, using a milling cutter, a hydraulic saw or hydraulic scissors (Figure 1). Hot cutting uses various forms of thermal cutting. The choice of method depends on the tank design .I), location (5.2), p
