Document O31Qw03w1aYXnbkoqvrkVvQwQ

received Repair and Removal of MAic i o 1984 Asbestos Insulation D. A. GOSSELIN CONTENTS 1. Repair and Removal situations 2. Asbestos-containing products to which these procedures may apply 3. Prevention of risk 4. Recommended procedures for repair, encapsulation or cladding of asbestos insulation 5. Recommended procedures for the removal of asbestos Insulation 6. Isolation and enclosure of work areas 7. Dust extraction equipment 8. Personal protective equipment 9. Disposal of stripped material 10. General 1. Repair and Removal situations 1.1 Asbestos in varying proportions has been widely used in insulation materials, especially for the thermal insulation ol steam-generating or process plants; for heating installations and services; as refractory linings in steel-making, metal and other industries, and in sites ranging from the smallest workshop to the largest industrial complexes such as oil refineries and power stations. At sea large quantities have been used both for thermal insulation and for the fire protection ol crew, passengers and cargo. It has also been used widely in land transport, in railway locomotives and rolling stock. It has been a favoured material for the reduction of fire hazards in buildings, particularly those where large numbers of people assemble. In these buildings it is used in the form of cladding of the steel structures and the formation of fire breaks. It has also been widely used for thermal and acoustic insulation. 1.2 In the course of maintenance, repair, alteration, removal or demolition, many instances occur which necessitate the repair or removal of asbestos-containing materials. Since by the nature of their insulating properties such materials are usually of low density and often found in a very dry state, their disturbance is likely to result in high concentrations of dust unless suitable precautions are taken. 1.3 The amount of respirable asbestos dust generated will depend on the nature of the product and the operation to be performed. It is essential that steps are taken to reduce the level of dust to the lowest practicable level and to ensure the protection of all personnel from risk of inhalation of harmful quantities of asbestos or other dusts, although the measures to be adopted will vary according to the nature and extent of the work to be carried out. This document is designed to assist alt those who may be concerned with the achievement of these aims. UCC 011590 2. Asbestos-containing products to which these procedures may apply 2.1 Compounds containing asbestos and applied by spray. 2.2 Compounds containing asbestos in the form of plastic self-setting mixes for covering pipes and equipment, often in conjunction with pre formed insulation materials. _ 2.3 Pre-formed insulation in the form of pipes, lags or slabs (or fabrications thereof, such as valve and flange covers). 2.4 Mattresses consisting of asbestos or man-made cloth covers or envelopes filled with loose asbestos fibre. 2.5 Asbestos cloth, tape or paper, often as an outer covering of the above-mentioned forms of thermal insulation. 2.6 Asbestos rope lagging, usually applied spirally wound onto steam or hot-water lines. 2.7 Refractory blocks or linings. 3. Prevention of risk 3.1 Regulations in some countries restrict the use of certain of the above-mentioned products (e g. by permitting their use for fire protection only). Even where certain uses no longer occur, installations and situations involving such materials will continue to exist for many years, so that the observance of suitable control procedures will be necessary for a long time in the future. Dust generated in demolition, whether or not the materials contain asbestos, is bound to be considerable so that measures for the protection of personnel and the prevention of public nuisance will be essential. 3.2 It should also be stressed that the removal of installed insulation for no other reason than that it contains asbestos may be ill-advised. In many cases the risk created by the removal would tar exceed any which would arise if the insulation were left in place effectively sealed. It is not always possible completely fo remove all sprayed asbestos; for example, where areas were sprayed during the construction process and subsequently have become inaccessible. Sometimes, as a result of impact or vermin attack, a portion of the surface may become opened up thus releasing fibrous material; in such situations it may well be more effective to repair the damage and seal the surface to prevent further release rattier than to attempt removal ' '4. Recommended procedures lor repair, encapsulation or cladding of asbestos insulation . 4.1 Where, as described above, a porlion ol the surface ol asbestos thermal insulation has become damaged so that there is a possibility ol trie release ol libres. various methods can be adopted to prevent such release. Whether the damage can be adequately and effectively encapsulated is a matter for judgement, taking into account the following 4.1.1 The nature and condition of the insulation. For example,.if the material is breaking away from its base complete removal will probably be unavoidable. 4.1.2 Whether the insulation is liable to further damage, e g. in the course of ordinary work traffic. 4.1.3 Whether the insulation is accessible or if major structural work would be necessary to allow its removal. 4.1.4 Wnat are comparative costs of removal or effective repair/sealing. 4.1.5 If me insulation has been provided lor statutory fire protection, whether this requirement can be met by otner means. 4.2 There are a number ot products which may be used to seal, encapsulate or clad existing asbestos-containing insulation materials, provided they meet the basic requirement of a continuous impervious surface. The mam classifications are as follows: 4.2.1 Flexible and semi-flexible polymeric or bituminous coatings. These are normally applied by spray as water-based emulsions but may be solvent-based. The finished surface nas low to medium strength but polymeric coatings used in conjunction with glass fibre fabrics can provide good impact resistance. 4.2.2 Inorganic cementitious materials, normally in tne form of fibrous or particulate-fified cements activated on site by water. These materials trowelled on to me surface of the insulation provide a rigid or semi-rigid hard-wearing surface which can be additionally strengthened with expanded metal mesh to give high impact resistance 4.2.3 Pre-formed sheets, panels or boards of metal, plasterboard, etc. (e g. for false ceilings and walls) assembled so that all joints are proper^ made and effectively sealed. 4.2.4 Cladding materials such as galvanised metal sneet or r bbea aluminium sheet, or wrapp ng materials such as polythene sheeting or reinlorced aluminium foil of suitable gauge, again paying particular attention to tne effective sealing ol all joints 4.2.5 Impermeable sealing tape (duct tape, fibre tape) can be used lor sealing small damaged areas, pamcularty on pipes ' 4.3 Selection of (tie scaling method and the material for a particular application will depend on me following (actors: 4.3.1 The degree ol protection required, e g is it an area vulnerable to impact ot abrasion? 4.3.2 Conditions ol wear; the surface toughness and flexibility required, e.g, does the surface require to be regularly decorated? 4.3.3 Type of surface. Certain treatments may impair sound absorption or anti-condensation characteristics or adversely affect the required 'spread of (lame' properties, 4.4 Protective procedures Specilic precautions will depend upon local situations and the type, extent and condition ol the surface to be repaired. Where me work is minor or the surface is not being dislurbed. it is normally sufficient to erect physical barriers and warning notices ten metres from the work, 4.4.1 The area to be sealed should be vacuum cleaned (using an industrial cleaner approved lor use with asbestos) to ensure the removal of all loose debris and dust particles to obtain good adhesion of the coating to be applied. 4.4.2 Damaged areas should be repaired before encapsulation to restore the required insulation properties, e.g. fire resistance, and to provide a suitable base for sealing. 4.4.3 If the condition of the damaged area is such that dust levels may exceed specified safety standards (a) the area should be completely enclosed to prevent the escape of dust to adjacent areas; (b) workers should be provided with appropriate protective equipment and follow the work procedures described in subsequent sections of this guide. 5. Recommended procedures for the removal of asbestos.insulation 5.1 identification of materials 5.1.1 Under certain circumstances there may be a need for preliminary sampling of the material to be removed in order to establish precisely the asbestos content. This may not always be obvious by visual examination and in suen cases scrutiny by sophisticated technical apparatus may be required in order to ascertain wun certainty the nature of fhe fibrous content. If local regulations require this, expert advice can be sought from the AIA or from one of its Member Associalions. 5.1.2 Generally, however, in view of the inevitable dustiness of such operations, full protective measures can and should be taken as a matter of course. Steps should be taken for the personal protection of workers involved and for the limitation of Ihe contaminated area to safeguard other workers and to avoid a joublic nuisance, regardless of the type nf toe 5.2 Selection of method There are broadly three mam methods lor the controlled removal ol asbestos insulation: Dry stripping Wei stripping . Stripping by high-pressure jefs In some cases circumstances may call lor a combination ol these techniques The circumstances determining the selection of method and Ihe factors to be considered are dealt with below 5.3 Dry stripping This method is essential where it is necessary to remove insulation near live electrical apparatus. It may also be desirable in other situations where the presence of large amounts of water would create difficulties or extra hazards. 5.3.1 Since no dust suppressant can be used, this method demands a very high standard of respiratory protection (See RCP 9.) 5.3.2 Enclosure of the work area must be of a very high standard, with air locks for access, and maintained under negative pressure to prevent leakage ol dust-laden air. (See 6.1.) 5.3.3 Surfaces from which insulation has been removed should be finished off by wire brushing under vacuum and in some cases it may be necessary to seal the exposed surface. 5.3.4 Thorough vacuum cleaning of the area on completion of the work, especially of the interior surfaces of the screening, is most important but should be easier than with other methods since the material remains dry. A Imal wet cleaning is also recommended. (See 10.4.) 5.4 Wet stripping Control by suppression of dust with water is most general, but can only be used where there is no electrical apparatus, or where such equipment can be isolated At the end of tne work it is of vital importance mat a competent person should ensure that it is safe to restore the electric supply. UCC 011591 5.4.1 For adequate suppression of Cost. |he msulalion material must be thoroughly welled before stripping- begins The material needs to be saturated; to this end the lagging should be pierced at intervals, preferably with hollow probes which will carry the water into the interior of the insulation material The addition of wetting agents to water greatly assists penetration 5.4.2 Careful use of low-pressure sprays (or fine mist) at the pomt of operation will help to keep down the dust levels in the immediate working-area. 5.4.3 Care must be taken to avoid an accumulation of wel material and slurry on the floor of the working-area, since this will create a hazard from slipping as well as increasing the work of subsequent cleaning up. 5.4.4 If the floor consists of open-mesh gratings, they should be covered, but great care is necessary to avoid the risk of slipping Floor surfaces wmch could be damaged by water (e g. hardwood blocks, tiles) should be covered before operations commence. 5.4.5 Insulation should be removed by cutting or sawing rather than by breaking with axes or hammers. As far as possible material should not be allowed to fall, but should be placed directly into suitable plastic bags tor ultimate disposal. _ 5.4.6 The wetted material should not be allowed to dry out. but should be removed while still wet and put into tne plastic Dags, re-wetting as necessary witn me low-pressure sprays 5.5 Stripping by high-pressure water jets This is a highly specialised technique employing waler jets normally operating at pressures above 750 psi (5.2 MN/m*) and usually restricted to fairly large-scale operations and lo sites where access is difficult, e g where the asbestos has been applied by spraying, and where otner techniques are unlikely to be satisfactory. Flowever it should not be used where electrical apparatus is present which cannot be isolated. 5.5.1 This method should only be undertaken by properly trained personnel and under competent and expert supervision, since the use of such high-powered jets is capable of causing serious injury. 5.5.2 In addition to normal enclosure and warning notices, signs marked 'Danger. High-pressure Spraying' should be displayed. 5.5.3 The specialised equipment must be properly maintained and the jet controlled by a `deadman's' control valve so that the high pressure is shut off on release. 5.5.4 The slurry produced will be collected by pump into specially designed'containers lor disposal and must be diverted Irom drain openings. 6. Isolation and enclosure of work areas 6-1 Whichever method of removal is employed, the area where the work is to be carried out should be isolated from other work areas, generally by enclosure within dust-impermeable screening. Strong plastic sheeting, with all joints carefully sealed, provides a most effective form of screening. Air locks must be provtded (or access and ventilation provided to ensure that the work area is maintained under negative pressure to prevent dust leakage. T v f,l if DANGER KEEP OUT ASBESTOS STRIPPING] i '.ife U ip 6.2 Warning nonces stiould be prominenlly displayed so that workers not directly involved with the removal are warned against, or prohibited from, entering the area as these workers will not be equipped wilh personal prolective equipment and probably not trained in the procedures lor the control of dust. 6.3 In some situations where the operation is limited and well controlled by wetting, and is not immediately adjacent lo areas occupied by other workers, it may be sufficient and practical for the area of operation to be roped off. Generally, however (and always if dry stripping is to be carried out), it is preferable (or the stripping-area to be screened off. 6.4 Access from the area of operations, to the washing and changing facilities /' must also be isolated so that men who have been engaged in stripping do not spread dust Irom contaminated clothing Tne most satisfactory arrangement is for a decontamination area to be sited immediately adjacent to the work area, so that workers pass through this before re-entering the unrestricted part of (he location. 7. Dust extraction equipment 7.1 When dry stripping is the method employed, reliance must be placed upon a combination of: (a) high-efliciency respiratory protection; (b) comprehensive enclosure of the dusty area; (c) dust-extraction equipment designed for use with asbestos dust and adapted for application to the point of dust generation. For stripping operations the equipment needs to be high efficiency filtered; transportable equipment will usually be required, although sometimes installed equipment may be adaptable for close application to the point of removal. 5 M UCC 011592 ! 7.2 Dust extraction devices are most effective when they are coupled with adequate Imitation of the area ot application by a capture hood concentrating the suction airflow close to the point ot dust generation 7.3 For some removal operations, for example where equipment of a similar type frequently requires stripping, it has been found practicable to develop a custom-built enclosure, coupled with extraction, within which the stripping can take place with no risk of escape of dust into the outside atmosphere. 8. Personal protective equipment 8.1 Experience indicates that even under wet conditions it is difficult to ensure that dust concentrations will at all times be successfully contained within the recommended levels. It is therefore advisable that personal protective equipment and clothing should always be provided and worn whenever and wherever such work is carried on. 8.2 Where small amounts of stripping are called for and water suppressing methods are used, cover-all protective clothing (such as a boiler suit) and asbestos-approved ori nasal respirators may be adequate. For all other situations full protective clothing, including hoods and boots, should be worn, together with positive pressure respirators Where concentrations are expected to be heavy and sustained (certainly when dry stripping is being carried out) the most sophisticated equipment, such as direct air-line breathing-apparatus, will be required. 8.3 Accommodation must be provided for the storage of personal clothing so that it will not become dust contaminated. Separate storage must be provided for protective clothing and equipment when not in use; this clothing and equipment must be isolated from personal clothing by the personal cleansing area 8.4 Facilities musl bo provided lor do-dusting me prolecttvo clothing upon leaving the wotk silo. Suitably adapted vacuuming equipment should be used for preliminary do-dusling delate Iho pioteclivo clothing is removed Washing facilities, including showers, should be provided lor use after removal ot the proleclive clothing and before moving into me personal clothing dressing-room. 8.5 Collection of protective clothing for cleaning must be strictly controlled. (See RCP 9.) In heavily contaminated conditions it may be necessary to change the clothing at the end ot each work period. Certain kinds o( disposable clothing may be suitable 8.6 Detailed recommendations for use, selection, care and training in the use of personal protective clothing and equipment are contained in RCP 9. 9. Disposal of stripped material 9.1 As with other forms of asbestos waste, stripped material must be collected into receptacles from which dust cannot escape during transit from collecting-point to disposal site. Heavy-duty polythene bags are most convenient and suitable for stripped insulation. It is recommended that these bags carry a warning label -- in some countries this is obligatory. 9.2 It is recommended that bags containing stripped asbestos material be collected into skips, kept separate from other wastes, and regularly cleared Irom the work site. 9.3 Detailed recommendations for the disposal of all types of asbestos waste, including control in transit and at tipping sites, are contained in RCP 3 and are applicable to the disposal of waste material from stripping operations. 9.4 When liigli pfev-nn: |*-t is employed, resulting in l.min quantities of very liquid slurry, if will be uocev.aiy to pump the slurry from colluding tanks into enclosed lankorlypu vehicles lor transit to approved locutions lor disposal in such a way that Ihero is no risk ot drying out 10. General 10.1 Training and supervision. If will be apparent from the foregoing that stripping-crews must consist of personnel who have been selecied and trained in the methods and hygiene disciplines required. Supervision ot a high standard of integrity and competence is essential, with particular regard to the efficiency ol the technical equipment and security of enclosures. 10.2 Maintenance. Routine inspeefion of all equipment, enclosures, accommodation and facilities should be scheduled and regularly reported and ( recorded. Plant so covered will include; Extraction equipment Vacuum cleaning equipment Wetting appliances, including high-pressure jets Enclosures and signs Protective clothing and equipment Hygiene facilities. 10.3 Cleaning. Whatever method of repair or removal is adopted, final cleansing of the site should be carefully carried out by wet cleaning, ideally in two stages with a 24-hour waiting-period in between to ensure that all dust is removed. UCC 011593