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25/30499772 DC BS 5970 Installation of thermal insulation systems on pipework, ductwork and associated equipment for all applications in the temperature range of −40 °C to +700 °C .Code of practice, 2025

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25/30499772 DC BS 5970 Installation of thermal insulation systems on pipework, ductwork and associated equipment for all applications in the temperature range of −40 °C to +700 °C .Code of practice, 2025

30499772_Form 36
BS 5970 [Go to Page]
Section 1: General
1 Scope
2 Normative references
3 Terms and definitions [Go to Page]
3.1 ambient temperature
3.2 coating
3.3 contractor
3.4 designer
3.5 finishing material
3.6 flexible elastomeric foam
3.7 flexible insulation
3.8 foamed in situ insulation
3.9 insulating brick
3.10 insulating concrete
3.11 insulated pipe support insert
3.12 loosefill insulation
3.13 microporous silica insulation
3.14 paint
3.15 polymeric plastics compound
3.16 pre-formed insulation
3.17 purchaser
3.18 reflective thermal insulation
3.19 sprayed insulation
3.20 sub-contractor
3.21 supplier
3.22 thermal insulation
3.23 thermal insulation system
Section 2: Design and materials
4 Design [Go to Page]
4.1 Reasons for insulation
4.2 Design requirements
4.3 Multi-layered systems and ship-lapped systems
4.4 Determining insulation thickness
4.5 Conditions at the point of delivery [Go to Page]
4.5.1 When assessing the thicknesses and quality of insulating materials for conveyance systems that involve guaranteed conditions of a fluid at the point of delivery, there should be close co-operation between the designer of the system and the ultim...
4.5.2 Where it is necessary for a fluid to emerge from a pipeline or duct system within a specific temperature range, the designer should confirm that the thickness of insulation applied is sufficient to achieve this point of delivery temperature.
4.5.3 BS EN ISO 12241 contains equations for calculating the temperature change of fluids moving through insulated pipes and ducts, which should be used by the designer when evaluating whether the intended thickness of insulation achieves the design o...
4.5.4 Incidental heat losses not directly related to those through the insulating material should be taken into account.
4.5.5 Where the fluid is expected to experience a physical change of state between liquid and vapour during its passage through the pipeline or duct system, the designer should make two separate calculations for the temperature change of fluids. The f...
4.5.6 To determine the mean temperature on which to base the calculations for heat loss, several calculations should be made in accordance with BS EN ISO 12241, on a trial-and-error basis because the temperature of the fluid, and therefore the tempera...
4.5.7 For systems incorporating supplementary heating, 4.5.3 to 4.5.6 should be disregarded and the designer should check and confirm that the heat loss through the insulated pipeline or duct system is less than the rating of the supplementary heating...
4.5.8 Where the system has condensate from pressure and heat loss during transmission of the fluid through the system, it should be removed where necessary. Where reducing condensation to a minimum is preferable, the thickness of insulation should be ...
4.5.9 The condition of dry gas or superheated vapour at the point of delivery essentially depends on the temperature and pressure loss during conveyance of the fluid through the system, as well as on the rate of mass flow; calculations should take all...
4.6 Protection of personnel [Go to Page]
4.6.1 Personnel should be prevented from touching hot or cold surfaces that could be harmful.
4.6.2 Where hot surfaces are not obvious, the following temperatures of bare surface or finished insulation should be regarded as threshold values of temperature above which people should be protected:
4.6.3 A temperature limit of 43 C should be used in calculations for short-term contact where services are accessed by high risk groups such as the children or the elderly. Where contact exceeds six hours, a lower temperature is required and should b...
4.6.4 Contact with very cold surfaces results in thermal shock or skin damage; protection should be provided for temperatures of approximately −10 C or below, where necessary.
4.7 Insulation against freezing [Go to Page]
4.7.1 When fluids are static in pipes or vessels and the ambient temperature is below the freezing point of the contained fluid, heat should be applied to the system to prevent freezing, e.g. by means of tracer pipes or electric heating elements, whic...
4.7.2 Pipes of small bore should have greater thicknesses of insulation for protection against frost conditions than pipes of large bore.
4.7.3 Freezing should be analyzed in two stages:
4.8 Protection against surface condensation [Go to Page]
4.8.1 A vapour barrier should be applied on the warm side of the insulation layer. Insulating material should not be applied to a cold surface in humid conditions without a vapour barrier unless the insulation system has sufficient vapour resistance, ...
4.8.2 Certain cold-insulation materials have a high resistance to the passage of water vapour; even so, they should have a vapour seal and all joints should be adequately sealed (see also Clause 11).
4.8.3 For plant situated outdoors, water-tight coatings should not necessarily be considered vapour-tight.
4.9 Protection of insulation and outer protection from damage during construction and future maintenance operations
5 Exchange of design data [Go to Page]
5.1 General
5.2 Information to be supplied by the designer [Go to Page]
5.2.1 General
5.2.2 Details of plant to be insulated
5.2.3 Operating conditions
5.2.4 Preparation of surfaces
5.2.5 Additional specification details
5.2.6 Basis on which the thickness of insulation is to be determined
5.3 Information to be supplied by the manufacturer or contractor
5.4 Drawings and documentation
5.5 Competency [Go to Page]
5.5.1 Introduction
5.5.2 Where a thermal insulation specialist is required [Go to Page]
5.5.2.1 The competence and capability of the thermal insulation contracting organization should be assessed by the purchaser prior to award of contract.
5.5.2.2 Thermal insulation installations should only be carried out by individuals who haveevidence of their competency as a skilled worker.
5.5.2.3 Individuals who undertake thermal insulation installations should hold a valid TICA Thermal Insulation CSCS Skilled Worker card or an equivalent qualification.
6 Factors affecting planning and programming [Go to Page]
6.1 General
6.2 Specialist insulation contractor engagement
6.3 Insulation quality management
7 Typical characteristics of insulating materials and insulation systems [Go to Page]
7.1 Thermal conductivity
7.2 Physical forms
7.3 Bulk density
7.4 Suitability for service temperature
7.5 Thermal expansions
7.6 Resistance to compaction
7.7 Resistance to water vapour penetration and to water absorption
7.8 Mechanical strength, resilience and durability [Go to Page]
7.8.1 Mechanical and compressive strength and resilience
7.8.2 Durability
7.8.3 Temperature limitations
7.9 Fire and explosion hazards [Go to Page]
7.9.1 Materials
7.9.2 Finishes
7.9.3 Aluminium cladding
7.9.4 Galvanized accessories
7.9.5 Electric earth bonding
7.9.6 Self-ignition
7.9.7 Hazards from contaminants [Go to Page]
7.9.7.1 Precautions should be taken in accordance with 7.9.7.6 as the chemical and physical processes involved are complicated and conditions hazardous.
7.9.7.2 The choice of an insulation system should be preceded by self-ignition experiments in a laboratory as the consequences of fire in an insulation system are most dangerous in locations where highly flammable and/or low-flashpoint materials are s...
7.9.7.3 In all circumstances, there should be a high standard of plant maintenance and vigilance to minimize the risk of accidental contamination by spillage or leaks.
7.9.7.4 Where an impervious finish is applied to provide protection against an otherwise dangerous combination of insulating material and spillage material, the potential for accidental and unobserved mechanical damage to the finish should be assessed...
7.9.7.5 The presence of flame-retardants and anti-oxidants in the body of the insulating material should not be regarded as fully protective because these compounds merely postpone, rather than preclude, the development of self-heating reactions once ...
7.9.7.6 Precautions should be taken to prevent fire hazards in air-conditioning ductwork in accordance with BS 5422, BS 5908-1 and BS 9999. Thermal insulation applied to ductwork within a building should always be free from substances that, in the eve...
7.9.8 Interface with fire-stopping materials and contractors
7.9.9 Fire resisting ductwork
7.10 Resistance to vermin, fungus and moulds
7.11 Health hazards [Go to Page]
7.11.1 Gloves should be worn when handling materials as some finishing cements are strongly alkaline when wet and can cause skin irritation.
7.11.2 Respiratory protective equipment should be provided and, particularly in confined spaces, air-fed hoods or respirators should be used for many materials, especially epoxy-resin compounds and those materials containing isocyanates.
7.11.3 Goggles and gloves should be used where necessary to prevent associated solvents causing damage to the eyes and skin irritation.
7.11.4 Barrier cream and adequate washing facilities should be provided. Protection should also be provided against respiratory hazards when these materials are sprayed.
7.11.5 Precautions should be taken when using fibrous insulants that cause skin irritation.
7.11.6 When insulating materials are handled, mixed or removed, precautions should be taken to minimize the risk of respirable dust particles entering the bronchial passages.
7.11.7 Before any stripping work is carried out, the type of insulating material used should be identified and relevant precautions taken to prevent insulants from deteriorating from vibration or heat soaking (see Clause 35).
7.11.8 Guidance on hazard statements should be sought from manufacturers safety data sheets and a COSHH assessment should be carried out by the thermal insulation contractor prior to commencement of work.
7.12 Removal and replacement
7.13 Heat capacity
7.14 Freedom from objectionable odour
7.15 Chemical resistance
7.16 Maintenance requirements
8 Corrosion [Go to Page]
8.1 General
8.2 Corrosion under insulation [Go to Page]
8.2.1 General [Go to Page]
8.2.1.1 Before applying insulation, the surface to be insulated should be dry and free from scale and contamination.
8.2.1.2 Systems that normally operate at below ambient temperature should not be insulated whilst there is a risk of condensation forming on the surfaces to be insulated.
8.2.1.3 Only dry, undamaged insulation should be used.
8.2.1.4 Insulation should be as close fitting as possible to the equipment/pipe surface.
8.2.1.5 Water ingress into the insulation system should be prevented. Where practicable, precautions should include:
8.2.1.6 The line of insulation, vapour barrier and cladding should be continuous through all pipe supports.
8.2.1.7 Where removable inspection points are incorporated into the insulation system, they should be designed to minimize the risk of water ingress, see Clause 33.
8.2.1.8 The mechanical system should be designed so as to allow the full insulation thickness to be applied on all man ways, pipe stubs, walkway supports, thermocouples, name plates, ladder supports and all other protrusions. All protrusions and termi...
8.2.1.9 The top plates of vertical manholes should always slope.
8.2.1.10 When insulating vessels, thicker insulation on the vessel top should be applied so that the lifting lugs are enclosed by the insulation so as to shed liquid.
8.2.2 Anti-corrosion barrier methods
8.3 Oxidation, acidic, alkaline and galvanic corrosion [Go to Page]
8.3.1 Oxidation
8.3.2 Acidic corrosion
8.3.3 Alkaline corrosive attack
8.3.4 Electrolytic corrosion
8.4 Stress-corrosion cracking [Go to Page]
8.4.1 Action of water-soluble chlorides and other halides on austenitic alloy-steels
8.4.2 Stress-corrosion attack on other metals
8.5 Attack by liquid metals
8.6 Attack on plastics pipes and equipment
9 Selection of thermal insulating materials [Go to Page]
9.1 General
9.2 Applicability of thermal insulating materials [Go to Page]
9.2.1 General
9.2.2 Refrigeration and general cold work between -40 C and 0 C [Go to Page]
9.2.2.1 The thermal resistance of the insulating material should be compatible with design or process control and economic considerations. It should also be capable of remaining resistant under the expected conditions of service and plant life. For ea...
9.2.2.2 Where the plant is to operate at temperatures below that of the ambient air, the insulating material should be protected by a vapour-sealing barrier. For full advantage, the insulating material should be resistant to the passage of water vapou...
9.2.2.3 Only dry insulating material should be used, which should be kept dry until after the vapour barrier has been applied and completed. The insulating material chosen should be one that can be secured in close contact with the insulated surface b...
9.2.2.4 Where necessary, the insulating material should be resistant to occasional defrosting of the plant, particularly if this is to be done by steam-purging which raises the temperature of the plant locally to a level above the softening point of t...
9.2.2.5 Where compression-resisting insulation is required, e.g. at pipe supports, sling points, or support areas for the inner container in double-skin construction, a compression-resistant load-bearing thermal insulation should be used e.g. cellular...
9.2.2.6 Many insulating and ancillary materials used for the insulation of low temperature plant are classified as combustible and therefore are potential fire hazards, which should be identified and materials accepted or rejected in accordance with t...
9.2.2.7 Where insulating materials, joints sealers and vapour barriers that are exposed to liquid oxygen, e.g. by direct spillage, leakage, or by the partial condensation of air, they should be of inorganic composition and should be free from oil or o...
9.2.2.8 The material of the vapour barrier should be selected to be resistant to other reactive oxidizing chemicals. It should be protected by an outer metallic cover adequately sealed (see also 7.9). When fixing the outer metallic cover, the vapour b...
9.2.2.9 When selecting insulating material for the protection of pipes of small diameter against frost conditions, trace heating should be used where the thickness of insulation is impracticable (see BS 5422:2023, Table 28 to Table 31).
9.2.2.10 To perform at the lower temperature and when using different types of insulating material for a portion of the plant, the inner layer should be used in sufficient thickness to maintain the temperature at the interface with the main insulant a...
9.2.3 For industrial applications at normal ambient and elevated temperatures [Go to Page]
9.2.3.1 Where flexible materials are used for plant of both regular and irregular shape, any risk of deformation caused by superimposed loads (e.g. by the weight of finishing material) should be mitigated against by providing additional support from t...
9.2.3.2 Where plant with double-skin construction, e.g. reaction or storage vessels, require the annular space to be packed with a loosefill insulating material (such as a loose mass of fibre or a porous granular aggregate), it should be uniformly pac...
9.2.3.3 Where plastic composition insulating materials are used for irregular shapes of plant, the plant should be preheated and the heat maintained until all the insulation is dry.
9.2.3.4 If used for repairs, wet plastic composition should be applied in successive layers, allowing each one to dry before the next is applied.
9.2.3.5 Plastic composition mixes are likely to contain soluble chloride salts, either as normal impurities or in the water used for forming the paste, as such they should not be used for direct application to austenitic steel surfaces due to the pote...
9.2.3.6 The foamed material should only be used within the correct temperature range and should not add to the fire hazard in the insulated plant.
9.2.3.7 Microporous silica insulation should not become wet, to prevent an irreversible breakdown of the microporous structure and loss of insulating properties.
9.2.3.8 Metallic surfaces are more effective than non-metallic surfaces in reducing absorption or emission of radiant heat, but allowance should be made for heat loss due to edge effects.
9.2.3.9 Fire hazard, moisture absorption, upper limiting-temperature and the thermal conductivity under the required conditions of use should be assessed and documented to determine the type of insulating board for a specific application.
9.2.3.10 Insulating fire brick and related pre-fired or formed rigid shapes should be used where the insulation has to be self-supporting or partially load-bearing or where it is to be exposed directly to hot gaseous products, e.g. for lining flues th...
9.2.3.11 The high crushing strength of calcium silicate blocks or cellular glass blocks combined with a low thermal conductivity makes them useful in partially load-bearing applications, and they should be used as a back-up to fire bricks where they h...
9.2.3.12 High temperature resistant fibre should be used in applications where low thermal mass and high resistance to thermal shock are important, such as in annealing furnaces or those used intermittently. Greater resistance to abrasion and mechanic...
9.2.3.13 Insulating concretes should be mixed with water immediately before application; they should be poured, spray-applied, or placed in position manually. Alternatively, the wet mass should be foamed or aerated so that large numbers of air-cells a...
9.2.3.14 When using two different types of insulating material for a portion of plant, the inner layer, for resistance to the higher temperature, should be used in sufficient thickness to reduce the temperature at the interface with the main insulatin...
9.2.4 For heating, ventilation and air conditioning applications between the temperatures ranges of 0 C and 85 C [Go to Page]
9.2.4.1 The thermal resistance of the insulating material should be compatible with design or process control and economic considerations. It should also be capable of remaining resistant under the expected conditions of service and plant life.
9.2.4.2 Where the plant is to operate at temperatures below that of the ambient air, the insulating material should be protected by a vapour-sealing barrier. For full advantage, the insulating material should be resistant to the passage of water vapou...
9.2.4.3 Domestic cold water pipes should be provided with a vapour seal to minimize the risk of condensation.
9.2.4.4 Where the plant is to operate at temperatures below that of the ambient air, the vapour barrier should be applied continuously and load bearing pipe support inserts should be installed to achieve a vapour seal.
9.2.4.5 Where the plant is to operate at temperatures above the ambient air, load bearing pipe supports should be installed. Pipe support inserts should be used on below ambient applications to reduce heat gains and control condensation and on above a...
9.2.4.6 The vapour barrier should be continuous and insulated pipe supports should be installed in all applications apart from at anchor points. Pipe supports should be suitable for application with the insulation material used in the system and shoul...
9.2.4.7 Only dry insulating material should be used, which should be kept dry until after the vapour barrier has been applied and completed. The insulating material chosen should be one that can be secured in close contact with the insulated surface b...
9.2.4.8 When selecting insulating material for the protection of pipes of small diameter against frost conditions, trace heating should be used where the thickness of insulation is impracticable in accordance with BS 5422.
9.2.4.9 In the absence of special requirements, the characteristics of thermal insulation systems with respect to reaction to fire should be in accordance with BS 5422.
9.2.4.10 Where the insulant requires an additional cladding material for either mechanical protection or protection against weathering, the surface emissivity of the cladding material should be assessed when determining the thickness of insulation.
10 Selection of securing materials [Go to Page]
10.1 General
10.2 Adhesives [Go to Page]
10.2.1 General
10.2.2 Classification according to use
10.2.3 Adhesive strength
10.2.4 Mechanism of curing
10.3 Mechanical securements [Go to Page]
10.3.1 The securing materials in this category generally should be classified as welded attachments, adhesive attachments, bolted fittings, mechanically fixed banding, self-adhesive banding or wire securements. For the application methods of securemen...
10.3.2 For mechanical securements to a vessel, the vessel manufacturer should be consulted regarding the site application of insulation and cladding for the specified vessel.
10.3.3 Designers should determine and specify appropriate means of insulation securement by reference to manufacturer instructions (see 4.2). The requirement for securement and type of securement for a particular application depends on the type, form ...
10.3.4 Electrolytic contact between metals of appreciably different electrochemical properties should be avoided (see 8.3.4).
10.3.5 On vertical piping, or vertical and downward-facing vessels and equipment, support attachments should be appropriate to the pipe/vessel/duct size and service, see 7.8.2 and manufacturer’s instructions. Any penetration of ventilation ductwork sh...
10.3.6 Where the use of adhesive attachments is specified, substrate type, weight of the insulation system, possible effects of vibration, ambient conditions, service temperature and the climatic limits and cure time of the adhesive should be assessed.
10.3.7 Attack by liquid metal should be prevented (see 8.5).
10.3.8 Site welding of securing and fixing devices should not be undertaken without first consulting the purchaser (client, the contractor and sub-contractors).
10.3.9 For large tanks, which are subjected to significant wind loadings, bolted fittings should only be used with attachments that are welded or fastened by means that provide equivalent restraint.
10.3.10 The size and spacing of banding and wire securements should depend on the materials chosen, on the design parameters of the insulation system (see 27.1.1) and manufacturer’s instructions.
10.3.11 When fixing attachments by welding, brazing, etc., metallurgical damage should be avoided. The conditions recommended in application standards, e.g. BS EN 13480 (all parts), should be followed.
10.4 Combination
10.5 Insulation hangers
11 Selection of vapour barriers [Go to Page]
11.1 General [Go to Page]
11.1.1 The designer of pipework, ductwork, associated equipment and other industrial installations should design the insulation system configuration to allow effective sealing of the vapour barrier, particularly at penetration points. The designer sho...
11.1.2 The vapour barrier should be used to minimize the ingress of water vapour into the insulating material. The barrier should always be applied to the warmer surface of the material (see 4.7.1), taking the form of a coating or sheet material resis...
11.1.3 Self-adhesive foil tape for heating, ventilation and air-conditioning (HVAC) applications should be used for sealing of foil vapour barriers, but it should be verified with the tape supplier that it is compatible with the foil and fit for purpose.
11.1.4 Unless the insulation has sufficient integral vapour resistance and the joints remain sealed throughout the lifetime of the installation, all insulation on plant working any time at below ambient temperatures should have an additional vapour ba...
11.1.5 Where insulation is installed over porous structures, e.g. concrete, the porous surface should be sealed.
11.1.6 Manufacturers’ advice should be sought when selecting vapour barriers for below ambient service temperatures, as multiple vapour barriers may be necessary.
11.1.7 For below ambient operation, the vapour barrier layer should not be exposed to mechanical damage.
11.1.8 If a weatherproof outer finish is used, its emissivity should be assessed and documented. Vulnerable vapour barriers should be mechanically protected.
11.1.9 The compatibility of the vapour barrier material with the chosen insulation should be identified and the material accepted or rejected accordingly, e.g. solvent-based materials should not be used directly over polystyrene.
11.1.10 The material used as a vapour barrier should have joints sealed in accordance with manufacturer’s recommendations.
11.1.11 If the fire performance characteristics of the insulation system used for cold work are not sufficient for the given application, an additional finish should be used, e.g. sheet metal, fire-resistant mastic, intumescent epoxy, or another type ...
11.1.12 Before the vapour barrier is applied, the insulant should be smooth and regular with all surfaces carefully butted together. Any adhesives or joint sealants should be fully cured and installed in accordance with manufacturer’s recommendations....
11.1.13 For below ambient applications, the supports for pipes, ducts and vessels should be external to the vapour barrier. The insulation inside the vapour barrier should be load bearing and of the same or compatible material, see 34.1. Support insul...
11.1.14 For maintenance purposes where insulation is removable, e.g. at flanged joints, at manholes, the main insulation should be cut short of the fitting and the vapour barrier sealed directly to the pipework or shell of the vessel. The removable po...
11.1.15 Where the service temperature of the plant cycles above and below the temperature of the ambient air, the vapour barrier/breather system should be designed to function during maximum and minimum temperatures, the time periods over which the pl...
11.1.16 The vapour barrier should be installed over the insulation on all plant working at temperatures below the ambient air.
11.1.17 The relevant dry finished thickness of the vapour barrier layer should be specified at the same time as the claimed permeance values. The method used should be documented to substantiate claims for permeance values as the method of test can in...
11.2 Vapour barriers for use over insulation applied to surfaces below dew-point
12 Selection of finishing materials, including ultimate treatment of finish [Go to Page]
12.1 General [Go to Page]
12.1.1 The properties of thermal insulating materials should determine the choice of protective covering, for example, a wet applied coating should have a firm base on to which it can be applied effectively.
12.1.2 A vapour barrier should be used for the insulation of plant at below ambient temperatures.
12.1.3 At below ambient temperatures, both the insulating material and the finish should be of a type that does not require heat for drying out.
12.1.4 To exclude all moisture from the insulation system, only dry materials should be used and they should be maintained dry before the vapour barrier layer is applied.
12.1.5 The joints of sheet finishing materials should be sealed, particularly those used for outdoor work.
12.1.6 Overlaps should be arranged to shed water or other liquid spillage, and the inner surface of metal covering should be protected to avoid corrosive or galvanic action from condensed moisture.
12.2 Classification of finishing materials
12.3 Reasons for use of finishing materials
12.4 Typical uses for finishing materials
12.5 Finishes for refrigeration work
12.6 Finishes to improve fire protective properties [Go to Page]
12.6.1 Finishes should have an appropriate level of fire and smoke performance for the application. Manufacturers should be consulted with regard to choice, permanence of effectiveness and method of application (see also 7.9).
12.6.2 Steel cladding should be used in preference to aluminium where there is a risk of development of fires due to the low melting point of aluminium.
12.7 Ultimate treatment of finish [Go to Page]
12.7.1 General
12.7.2 Painting [Go to Page]
12.7.2.1 Painting as a final finish
12.7.2.2 Indoor applications
12.7.2.3 Outdoor applications [Go to Page]
12.7.2.3.1 General
12.7.2.3.2 UV degradation of insulation systems
12.8 Identification of the contents of an insulation system
13 Selection of thermal insulation systems [Go to Page]
13.1 General
13.2 Optimum efficiency
13.3 Extent of insulation system
13.4 Determining factors [Go to Page]
13.4.1 Temperature
13.4.2 Mechanical stability
13.4.3 Resistance to degradation
13.4.4 Thermal efficiency
13.4.5 Type and dimensions of the plant to be insulated
13.4.6 Compatibility of the components of the insulation system
13.4.7 Total weight of the insulation system
13.4.8 Space for insulation system
13.4.9 Potential hazard to health
13.4.10 Corrosion hazards
13.4.11 Fire hazard
13.4.12 Environmental aspects
Section 3: Site considerations
14 Basis and method of presenting schedule of work for agreement between purchaser and contractor [Go to Page]
14.1 Before work at site begins, the purchaser (who could be the client, the main contractor or sub-contractor) should provide the contractor carrying out the insulation work with a clear programme indicating when the site is available and a completio...
14.2 At the enquiry stage, the purchaser should indicate any special conditions known to exist. The contractor should submit to the purchaser a corresponding document giving an assurance to meet the agreed programme dates and that adequate materials a...
14.3 The purchaser and contractor should assess and document their responsibilities regarding supply or application of insulation-securing attachments and any necessary preparation of surfaces, e.g. removal of oil, grease and rust, painting, applicati...
14.4 Where areas of plant to be insulated are to be left bare for a period, e.g. to make provision for inspection or tests to be carried out later, this should be indicated to the contractor at the tender stage. Temporary terminations in the insulatio...
14.5 Where the satisfactory application of insulating and finishing materials is dependent on weather conditions, including frost, rain, ambient air-temperature and humidity, the manufacturers’ installation instructions should be consulted and protect...
14.6 For the contractor to operate on an efficient and economical basis, complete sections of plant should be released for insulation installation and any limitations of access should be notified.
14.7 The contractor’s tender and purchaser’s subsequent requisition should contain a clear description of the extent of work covered by the contract. If the contractor is requested at site to carry out work outside the scope of the contract, immediate...
14.8 The thermal insulation contractor should provide a handover pack to the purchaser to confirm satisfactory completion of the work. Protection of work after this point is the responsibility of the purchaser. If a contractor is called upon to repair...
14.9 Before work at site begins, the purchaser and contractor should be in complete agreement regarding the extent of a contract working week, working conditions for personnel and all other items that affect the maintenance of previously approved prog...
14.10 There should be agreement between the purchaser and contractor on the need for, and protection of, completed work after handover.
15 Packaging and transport to site [Go to Page]
15.1 Methods of packing
15.2 Protection against crushing
15.3 Packing of plastic compositions and finishing compositions or cements
15.4 Methods of identification of packages
16 Labour and supervision
17 Provision of storage space, protection and safety during storage [Go to Page]
17.1 Space should be provided for the contractor to store insulation and ancillary materials.
17.2 All materials should be stored in a dry atmosphere and undercover. Manufacturer’s storage instructions should be consulted in case of special requirements.
17.3 Stock rotation should be employed so that the first material supplied to site is the first to be used.
17.4 Cartons or packs containing slab insulation should be stored on a flat surface.
17.5 Bags containing mattress insulation should be stacked flat in accordance with manufacturer’s instructions.
17.6 Sheet metal should be delivered as single sheets, coils or in stacks, dependent on the type of handling facilities in the stores. The first layer of sheets not exceeding 0.5 tonnes, or the first stack, should be stacked on a pallet board. The sec...
17.7 Sheet edges should be examined at least monthly to see if any discolouration has taken place. If discolouration occurs, the faces of the sheets should be examined and, if necessary, dried and re-stacked.
17.8 When storage is required for longer than three months, the supplier should be consulted for recommendations on packaging the sheets before storage.
17.9 Adhesives, coatings and mastics should be stored undercover in a dry atmosphere in accordance with manufacturer’s instructions. The shelf life and the recommended storage condition should be maintained, particularly with two-part adhesives, masti...
18 Provision of power, water, light, heat and accommodation for personnel [Go to Page]
18.1 Power and water
18.2 Light and heat
18.3 Accommodation and storage
19 Provision of access equipment
20 Responsibility for studs, cleats, etc.
21 Observance of site safety, fire precaution and security arrangements
22 Protection of adjacent equipment and surfaces
23 Clearing waste material from site
24 Health considerations
Section 4: Application methods
25 Methods of application and practical consideration [Go to Page]
25.1 Insulating materials should be kept clean and dry when in storage and during erection.
25.2 Apart from certain load-bearing materials, most types of insulating materials should be supported or reinforced when applied; they should also be secured to the surface to be insulated. For these reasons, where necessary, fixing accessories shoul...
25.3 To maintain the thermal efficiency of the insulation systems, all insulating materials, however fixed, should be in close contact with the surfaces to which they are applied unless an air space is specially required, e.g. for acoustic purposes or...
25.4 Where the main insulation consists of pre-formed or flexible material, all edges or ends should be closely butted; for multilayer work, all joints should be staggered.
25.5 Insulation work should be carried out with the plant off-load, where practicable.
25.6 Before any section of the insulation work on piping, vessels or ductwork begins, all hangers, brackets, pipe clips, trace-heating, etc. should be in position and the necessary acceptance tests for pressure/vacuum, etc. should have been carried out.
25.7 The junction between removable and permanent insulation should be arranged so as to be readily discerned, e.g. by identification signs.
25.8 The design of plant and pipe layout should enable safe access when insulating complicated plant.
25.9 The plant designer should allow a minimum clearance of 50 mm beyond the full extent of thermal movement between insulated plant and structural, or other, surfaces. Where the shielded depth is greater than 300 mm, there should be sufficient cleara...
25.10 Where pipe banks against walls or ceilings are involved, the designer should take into account the sequence of the fixing of the insulating material and its finish, and should make all necessary provisions to enable application.
26 Surface preparation and accessories [Go to Page]
26.1 Surfaces to be insulated should be clean, dry and free from grease, dirt, loose rust, scale or any contaminants. Usually the surface should be coated (see Clause 8). This coating should not be applied until all welded attachments have been fixed ...
26.2 Other forms of surface protection should be provided for specific situations, e.g. wrapping austenitic stainless steel surfaces with aluminium foil to protect against stress corrosion (see 8.4).
27 Securements [Go to Page]
27.1 General [Go to Page]
27.1.1 The insulating material should be secured directly to the surface to be insulated, e.g. by means of adhesive (see 10.2, 27.2 and 28.3), but where not possible, some form of mechanical accessory should be used to secure it to the permanent attac...
27.1.2 When using bands, wire, pins/hangers or any other means to mechanically secure insulation to a surface, any damage to the water vapour barrier should be prevented.
27.1.3 The vapour barrier should be maintained at all times.
27.1.4 Flexible insulating mattresses that have wire mesh covering integral in their construction, and have inter-surface ties, should be impaled over the main attachments and further secured by tightly fastening together the adjacent edges of the out...
27.1.5 If split-pin or fork-stud attachments have been used, the insulation should be secured by bending the prongs of the fork arrangements either through and over reinforcing mesh or through washers. Typically, the prongs of the pins/hangers or stud...
27.2 Adhesives and fastenings [Go to Page]
27.2.1 Where adhesives are used to form a bond between adjacent insulation elements or the insulation and the surface to be bonded; adequate “open time” should be allowed for evaporation of the solvent before making a bond between materials of low per...
27.2.2 If adhesives are used as an aid to erection, mechanical support should be provided. The manufacturer’s advice on the effective temperature range of the adhesive should be sought as many adhesives do not continue to operate effectively at very l...
27.2.3 Wherever possible, and where recommended by the manufacturer, additional mechanical support should be used in the form of banding, insulation hangers or self-adhesive tapes.
27.3 Self-adhesive foil tapes [Go to Page]
27.3.1 Before using self-adhesive foil tape for securement, the following should be assessed:
27.3.2 Self-adhesive foil tape applied to circumferential joints for securement should be overlapped on to itself by a minimum of 75 mm.
27.3.3 The minimum thickness of self-adhesive foil tape used for securement purposes should be not less than 30 micron and should have a temperature range suitable for the application it is being used for.
27.3.4 Both the insulation and foil tape manufacturers’ advice should be sought before using self-adhesive foil tape as a sole means of securement.
27.3.5 All surfaces should be clean and free of dust, scale, oils and other contaminants before the application of the self-adhesive foil tape.
27.4 Securement (wires and banding) [Go to Page]
27.4.1 Lacing wire [Go to Page]
27.4.1.1 The sizes of wire should be 1 mm diameter for general use, or 1.5 mm for heavier use. For refrigeration work, plastics tapes should be used instead of wires. Other soft wires should be used for special applications.
27.4.1.2 Lacing wires should be fastened either by wrapping them around each attachment or by means of nuts, clips or washers at each fixed point.
27.4.1.3 Where lacing wire is used, it should be applied so as to avoid cutting into the insulation material. If this is not possible, an alternative approach should be used e.g. bands (see 27.4.2).
27.4.1.4 Lacing wire that is likely to be in direct metallic contact with a final cladding of aluminium sheet should be coated with a plastics material to avoid electrolytic corrosion in the locations of contact.
27.4.2 Bands
27.4.3 Pipe insulation
27.4.4 Large flat surfaces
27.4.5 Cylindrical surfaces [Go to Page]
27.4.5.1 Circular ducts
27.4.5.2 Large cylindrical vessels
27.5 Reinforcement [Go to Page]
27.5.1 Metallic reinforcement should be used with spray-applied fibrous insulation, wet-applied finishing compositions and wet finishing cements, but they should also be used for retaining dry fibrous insulation and various types of pre-formed materials.
27.5.2 Galvanized steel reinforcing mesh and securing devices should not be subjected to temperatures in excess of 65 C under conditions of possible high humidity. Heat-resisting alloy should be employed for all service temperatures in excess of 400 ...
27.5.3 Where substantial mechanical strength is required, e.g. for resistance to compression, square-pattern reinforcing mesh should be used, which vary, according to the requirements, from strands of 2 mm diameter at 40 mm spacing, to strands of 6 mm...
27.5.4 Where metal reinforcement is to be located over the outer layer of insulating or finishing material and is likely to be in direct contact with cladding of a dissimilar metal, precautions should be taken to avoid electrolytic corrosion action, e...
27.5.5 Where mechanical strength is required, e.g. for puncture resistance, open-weave glass or polyester cloth or scrim should be embedded between layers of weatherproof or vapour-proof mastics.
27.6 Mechanical securements (attachments) [Go to Page]
27.6.1 Attachments should be used either for the direct support of insulating materials or as fixtures to which insulation supports are secured, e.g. by bolting (see Clause 20).
27.6.2 The contact area for application of stud-welded attachments should be related to the thickness of metal to which each one is to be applied so as to avoid lack of fusion, undercutting or over-penetration. If the metal of the surface to be insula...
27.6.3 Where angles, flat cleats and similar large attachments are used, they should be secured by electric arc welding or gas welding. A procedure appropriate to the materials, the thickness of the component and that of the attachment should be used....
27.6.4 For surfaces on which site-welding of attachments is not recommended, e.g. for certain types of alloy-steel, or where subsequent internal temperature and pressure could be a hazard, metal pads should be welded in appropriate locations. These sh...
27.6.5 For the choice and methods of attachment of plastics or metal support clips with an adhesive, the adhesive manufacturer’s literature should be consulted.
27.6.6 Where adhesive insulation hangers are applied to flat smooth surfaces, e.g. galvanized metal or plastics ducting, the surface should be free from contaminants, scale or oxidants. Materials should be secured according to their weight and type. T...
27.6.7 The selection and application of split pins, fork studs and similar fastenings should follow the recommendations for studs, see 27.6.1 to 27.6.6; the contact area should not exceed 80 mm2.
27.6.8 When welding, the difference in thermal expansion between the welded contact edge and the free edge should be assessed and, if it is significant, distortion of the attachment should be avoided by the introduction of saw cuts at intervals along ...
27.6.9 To avoid mechanical damage to the stud during transit or during erection of the plant, a thick threaded nut should be welded on to the surface to be insulated, providing a fixture into which a threaded stud can be screwed at a later stage.
27.6.10 The locations of attachments should be determined by calculating the weight of insulation to be attached, as well as on the size and orientation of the surface and on the degree of vibration to which the plant is subjected under service condit...
27.6.11 Welded attachments should penetrate into the insulating material only to the minimum extent necessary to provide support. The cross-sectional area of the attachments should be the minimum, consistent with the required mechanical strength to av...
27.6.12 The insulation or finish should be protected from being torn by welding attachments where there is a risk of being subjected to the same extent of thermal movement as the insulated surface, e.g. by using expansion or slip joints.
27.7 Insulation supports [Go to Page]
27.7.1 Distinction between the main supports for the plant or equipment and those required only to support the thermal insulation together with any associated finish should be identified and documented. Supports for the plant and equipment, e.g. pipe ...
27.7.2 Unless otherwise recommended, supports for insulation and any associated cladding should only have to bear relatively light loading and consist of metallic flat bars, rings, part rings, varying lengths of angle, or studs.
27.7.3 Flat bars, rings and angles should rest on stud or cleat attachments welded in the appropriate locations to the surface to be insulated (see Figure 10). Where used, angle supports should be bolted to the welded attachments on the plant, or they...
27.7.4 Where stud-type supports are used for pre-formed or flexible insulating mattresses; they should serve as suspension points for the metal-mesh covering of spray-applied insulation (see Figure 6 and Figure 7, and 27.4.4).
27.7.5 Alternatively, especially for vertical alloy-steel pipework, the studs should be welded radially to a ring that is clamped around the pipe at the required vertical intervals. Support lugs or pads for the rings should be welded on to the pipe at...
27.7.6 Studs should not be greater than 10 mm in diameter, or equivalent contact area, for gun welding. Angle cleats and flat bars should be approximately 5 mm to 10 mm thick, depending on the weight of insulation (and finish) to be supported.
27.7.7 Support angles should not penetrate the insulation to a distance greater than its total thickness less 10 mm unless through-metallic connection between cold and hot surfaces of the insulation is avoided. This should be avoided by interposing a ...
27.7.8 On large diameter tanks, the cladding from the tank surface should be directly supported to accommodate wind loading conditions (see 29.3.2.7 and Figure 8, Figure 12 and Figure 13).
27.7.9 On vertical surfaces, provision should be made for insulation supports (e.g. flat bars, angles or studs as agreed; see 10.3) to take the dead weight of the insulation. These supports should project halfway through the insulation thickness or, f...
27.7.10 To reduce heat transfer and cold bridging to a minimum, the cross-sectional area of each insulation support should not be greater than that necessary to achieve the required mechanical stability.
27.7.11 Additional supports should be used for the insulation on the ends of vessels of over 1.5 m diameter. Pins/hangers of 5 mm diameter should be provided on a triangular pitch of approximately 300 mm. The length of the pins should be equal to the ...
28 Cold insulation – Application for systems operating in the temperature range −100 C to ambient temperature [Go to Page]
28.1 General [Go to Page]
28.1.1 The outer surface of the insulation used on systems operating at below ambient temperatures should be protected by a continuous water vapour barrier. The vapour barrier should not be pierced or compromised by supports. At discontinuities and at...
28.1.2 Where the total thickness of insulation to be applied exceeds 50 mm, the insulation should normally be applied in multiple layers, each no thicker than 50 mm. As some materials are suitable for applying in single or multiple layers of greater t...
28.1.3 In addition to the recommendations in Clause 27, where metal surfaces operating below the dew-point require anti-corrosion coating, the coating should be thoroughly dry before the insulation is applied. The initial protective layer should be co...
28.1.4 Insulation should be carried out on surfaces above the dew-point temperature of the ambient air at the time of application. If surfaces are below the dew-point temperature or below freezing, the surface should be de-iced and wiped dry before th...
28.1.5 The manufacturer’s recommendations should be followed, particularly in respect of the following:
28.1.6 Where possible, skewers should be avoided. Where used, they should remain within the insulation to avoid compromising the vapour barrier.
28.1.7 Further guidance should be sought from the manufacturer where two or more layers of insulating material are required (see 28.3.1) and the service temperature is below −20 C. Where a vapour tight or air tight seal is required, joint-sealer mast...
28.1.8 The vapour barrier should be designed as an integral part of the insulation system and applied as soon as possible so as to keep the insulation dry (see Figure 14 and Figure 15). The vapour barrier should not be used as the final surface finish...
28.1.9 Where insulants of an abrasive nature are to be used (e.g. cellular glass), an anti-abrasion bore coating to the inner face of the insulant should be applied.
28.2 Contraction joints [Go to Page]
28.2.1 Where the insulating material is not sufficiently compressible to accommodate the differential thermal movement, contraction joints should be used (see Figure 3). Detailed guidance on requirements for contraction joints should be sought from ma...
28.2.2 Contraction joints should be provided immediately below insulation support rings on vertical pipes and at intervals on horizontal pipes. The pipe material, the insulation material and the difference in temperature between ambient and service te...
28.2.3 The insulation should be cut and fitted accurately. Pre-formed bends of insulating material should be used to allow an accurate fit without open joints. Leaving gaps in joints to be filled with plastic composition or rough slivers of insulation...
28.2.4 Where the service temperature is very low or where there are appreciably large fluctuations of temperature, and depending on the type of insulating material and the configuration of the insulation system, contraction/expansion joints of the typ...
28.3 Typical erection methods [Go to Page]
28.3.1 Using pre-formed insulating materials
28.3.2 Using solvent-based adhesives
28.3.3 Using bedding compounds
28.3.4 Dry erection
28.3.5 Vessel supports
28.4 Pipework and fittings [Go to Page]
28.4.1 General
28.4.2 Pipework [Go to Page]
28.4.2.1 Pre-formed insulating material [Go to Page]
28.4.2.1.1 General
28.4.2.1.2 Cellular glass
28.4.2.1.3 Elastomeric foam
28.4.2.2 In situ foam [Go to Page]
28.4.2.2.1 General
28.4.2.2.2 In situ foam injection application method [28.4.2.2.1a) and 28.4.2.2.1b)]
28.4.3 Pipe bends [Go to Page]
28.4.3.1 Pre-formed insulating material
28.4.3.2 Elastomeric foam
28.4.4 Flanges, valves and other fittings [Go to Page]
28.4.4.1 General
28.4.4.2 Fixing
28.4.4.3 Vapour sealing
28.4.4.4 External finish
28.4.4.5 Fitting covers directly fabricated from insulation material
28.4.5 Pipe supports
28.5 Vessels and large curved surfaces
28.6 Storage tanks [Go to Page]
28.6.1 General
28.6.2 Corrosion protection
28.6.3 Nozzle connections and manholes
28.6.4 Base of tank
28.6.5 Shell and roof of tank
28.7 Air-conditioning ductwork operating below ambient temperature [Go to Page]
28.7.1 General [Go to Page]
28.7.1.1 Air-conditioning ductwork operating below ambient should be insulated in accordance with 29.4 (see BS 9999 for fire performance requirements, and 7.9 and 12.6 for fire hazards).
28.7.1.2 Fresh-air ducts and exhaust ducts carrying cold air should be insulated to prevent condensation. The insulation should be continuous over the whole length of the duct, including fans, heat exchangers and filter casings carrying cold air.
28.7.1.3 Materials that are suitable for insulating ductwork operating in this temperature range should be used (see Table 2).
28.7.1.4 Insulation over 50 mm thick should normally be applied in two layers and should have staggered joints. Manufacturer’s guidance should be sought.
28.7.1.5 For ductwork located externally to buildings, metal surfaces should be given corrosion protection before the application of pre-formed insulation and a waterproof finish. Termination points should be sealed, i.e. inspection doors, expansion j...
28.7.1.6 Ducts running alongside each other should be individually insulated (see 4.2).
28.7.2 Fixing and adhesion
28.7.3 Vapour barriers and finishes [Go to Page]
28.7.3.1 Where a finish for indoor ducting is applied to provide an adequate vapour barrier for the design conditions; it should be robust enough to withstand mechanical damage or cleaning, and where necessary, have a visual appearance compatible with...
28.7.3.2 Ductwork situated outdoors should have a UV resistant, vermin resistant, weatherproof finish.
28.7.3.3 Where insulation is used with a factory-applied vapour barrier adhered to its surface, all joints in the vapour barrier should be sealed, either by bonding the overlaps, where provided, with adhesive or by sealing with matching self-adhesive ...
28.7.3.4 Where plain un-faced slabs are used and wrapped with the vapour barrier facing on site, the overlaps of the facing should not be directly over the joints in the slabs.
28.7.3.5 Conditions encountered on many sites where insulation is applied should be assessed and documented to prevent them delaminating and impacting the successful adhesion of self-adhesive tapes. Where applicable, this problem should be prevented b...
28.7.3.6 Where insulation is to be secured and protected by means of a polymeric vapour barrier coating, this should be applied in two coats and reinforced with a membrane of cotton or open-weave glass fabric between coats, the first coat being used t...
28.7.3.7 Where a protective finish has been applied to the substrate of the duct, it should be checked for damage. If it is damaged, the contractor should notify the purchaser (the client, the contractor and sub-contractors) so that the coating is mad...
28.7.4 Flanges, stiffeners and other fittings [Go to Page]
28.7.4.1 The insulation and finish should terminate clear of access openings and hinged or removable doors.
28.7.4.2 Flanges and stiffeners should be covered either with insulated box-type fittings or by increasing the general thickness of insulation to give at least 5 mm cover (see BS 5422 for appropriate thicknesses).
28.7.5 Fire dampers and fire stopping [Go to Page]
28.7.5.1 The insulation and finish should terminate clear of instruments, detectors, and damper operating gear and accessories to permit free opening and closing of the dampers.
28.7.5.2 Where there are fire dampers within ducts, combustible thermoplastic insulation should stop approximately 1 m clear of the damper (which could become very hot in a fire) to prevent excessive radiation of heat to the insulation on the side rem...
28.7.6 Pre-insulated ductwork
28.7.7 Internal ductwork lining [Go to Page]
28.7.7.1 The total thickness of insulation applied should be sufficient to meet all design specifications; if only internal insulation is used, but does not meet heat loss/gain targets, the need for additional external duct insulation should be assessed.
28.7.7.2 Where the risk of fibre erosion exists, the internal insulation should be covered by a plastics film, glass scrim fabric, glass staple tissue, neoprene-coated glass-fibre mat, perforated sheet metal or perforated board. Where plastics film or...
28.7.7.3 For conditions of high air velocity, only sheet metal covering backed by film should be used. The leading edge and all joints should be sealed to prevent pick-up of the fibres by the air flow.
28.8 Flat and irregular surfaces (including machinery)
29 Hot insulation – Application for systems operating in the temperature range above ambient to +870 C [Go to Page]
29.1 General [Go to Page]
29.1.1 Application
29.1.2 Attachments
29.1.3 Provision for differential thermal movement
29.1.4 Sliding and bellows expansion joints, and corrugated piping
29.2 Pipework [Go to Page]
29.2.1 General considerations
29.2.2 Pre-formed materials
29.2.3 Flexible materials [Go to Page]
29.2.3.1 Fabric-covered mattresses should be made from a flexible medium and filled with a filling that contains a minimum of dust or foreign matter. The hem of the fabric cover should be folded twice before sewing. The inner faces of mattresses and t...
29.2.3.2 Flexible insulating blankets or mats should be secured with circumferential bands of metal or plastics strip, as described in 27.1.1, with the exception of circumferential tie wires, which should be used when the ultimate finish is to be of s...
29.2.3.3 For vertical and near-vertical piping, downward displacement of flexible insulating materials should be prevented. While support from below is suitable for many pre-formed materials, flexible insulating materials should be suspended from above.
29.2.4 Foamed in situ
29.2.5 Sprayed insulation
29.2.6 Loosefill insulation
29.2.7 Insulating concrete [Go to Page]
29.2.7.1 For highly porous pre-fired brick aggregates, the aggregate should be soaked in water for 12 hours and then quickly drained before being mixed with the cement and the measured amount of water for use. Insulating concrete should not be used wh...
29.2.7.2 Linings for large pipes should be anchored by Y-studs or V-anchors welded to the inner surface; for horizontal pipes, the upper curved surface should have studs at a closer pitch than those over the lower surfaces. Externally shielded pipes s...
29.2.7.3 The concrete for lining pipes should be applied by hand trowelling, spray-gun or, in certain specialized cases, by centrifugal spinning.
29.2.7.4 After application, the insulating concrete should be cured by maintaining in a moist condition (e.g. by covering with wet sacks, spraying with water) for 24 hours. The initial heating should be relatively slow (see manufacturer’s instructions...
29.2.8 Pipes with trace heating [Go to Page]
29.2.8.1 Application of insulation to pipework heated by external tracing pipe
29.2.8.2 Electrical tracing
29.2.8.3 Application of insulation to pipework heated by jacketing, lancing or integral heating
29.2.9 Piping bends
29.2.10 Flanges, valves and other fittings on hot piping [Go to Page]
29.2.10.1 General
29.2.10.2 Flange and valve jackets
29.2.10.3 Flange and valve boxes
29.2.10.4 Oversized sections
29.2.10.5 Plumber’s joint
29.2.11 Plastic composition [Go to Page]
29.2.11.1 All plastic compositions should be mixed with clean, fresh water. Before application of plastic composition, the piping should be heated to a minimum temperature of 65 C. This temperature should be increased progressively with the applicati...
29.2.11.2 If plastic composition materials are used to secure attachments on pipework, reinforcing metal mesh should be provided over the first 25 mm of thickness and subsequently at each 50 mm increment of thickness and over the final surface.
29.2.11.3 For thicknesses of insulation greater than 50 mm on pipes of 150 mm nominal size and over, an intermediate reinforcing layer of metal mesh should be used, as detailed in 27.5, taking into account the temperature limitations of galvanized wir...
29.3 Vessels and large curved surfaces [Go to Page]
29.3.1 General considerations
29.3.2 Storage tanks [Go to Page]
29.3.2.1 Corrosion protection
29.3.2.2 Nozzle connections and manholes
29.3.2.3 Stairway connections
29.3.2.4 Base of shell
29.3.2.5 Insulation support rings
29.3.2.6 Cladding securement
29.3.2.7 Roof insulation
29.3.3 Pre-formed materials
29.3.4 Plastic composition
29.3.5 Flexible materials
29.3.6 Foamed in situ
29.3.7 Sprayed insulation [Go to Page]
29.3.7.1 General considerations
29.3.7.2 Mineral fibre
29.3.7.3 Spray-applied rigid organic foam (polyurethane or isocyanurate)
29.3.8 Loosefill insulation
29.3.9 Insulating concrete
29.4 Air ducts and gas flues [Go to Page]
29.4.1 Air ducts (building services) [Go to Page]
29.4.1.1 Insulation should be applied to ductwork, fans, heat exchangers, filter casings, etc., carrying conditioned air. Fresh-air ducts and exhaust ducts carrying hot air should be insulated to prevent excessive heat gain, either to the contained ai...
29.4.1.2 Insulation should be applied to ductwork in accordance with 28.7.
29.4.1.3 Thicknesses of thermal insulation should be in accordance with BS 5422 or, where specific requirements are stated, calculation should be in accordance with BS EN ISO 12241. When transient working temperatures are below the dew-point of the am...
29.4.2 Hot air ducts (industrial applications) [Go to Page]
29.4.2.1 Insulation should be applied to conserve heat. Insulation thickness varies with service temperature, but less than 50 mm thickness should not be used. For insulation thicknesses greater than 75 mm, the insulation should be applied in multilay...
29.4.2.2 The insulating material should be pre-formed slabs of calcium silicate, perlite or inorganically-bonded man-made mineral fibre, or cellular glass. Alternatively, where man-made mineral-fibre mattresses and blankets are used, excessive compres...
29.4.2.3 The insulation material should be firmly secured to the duct with fork ties, split pins or solid studs, over which the insulation is impaled. Where a rigid slab material, e.g. calcium silicate is to be installed, the insulant should be predri...
29.4.2.4 Wet-applied finishing compositions should be reinforced normally by woven wire mesh, as described in 29.4.2.3, or by expanded metal mesh on suspended surfaces (see 27.5.1 and 30.1). Hard-setting compositions reconstitute in the presence of wa...
29.4.2.5 Metallic cladding should be used on outdoor hot-air ducts, because it provides fire resistance and good mechanical and weather-protection. Water ingress into the insulation should be prevented because this significantly increases the weight o...
29.4.2.6 Where a metal outer finish is to be installed, it should be supported on insulated plates mounted on threaded studs or insulated angle cleats or rails. The insulation support system should be designed to allow for differential expansion so th...
29.4.2.7 To create a “straight line” appearance, a rail system for the retention of the metal sheets should be used. The rail should be stood-off from the duct surface sufficiently to clear the majority of the stiffening members.
29.4.2.8 Outdoor hot-air ducts should have all joints in the metal sheets sealed with a non-setting weatherproof sealing compound. Where practicable, the roofing sheets should be extended over the sides to form eaves. Where profiled sheet is used, it ...
29.4.2.9 The insulation and finishing material should finish clear of any instruments, detectors, damper operating gear and accessories to permit free access and movement. They should also finish clear of any access openings and doors (see 28.7.2 Note...
29.4.2.10 The thickness of metal cladding, where used, should be in accordance with Table 7.
29.4.2.11 Stiffeners that project beyond the main line of the insulation should be covered with not less than 25 mm or half the full thickness of the main insulation, whichever is the greater, built up so as to enclose the metal of the stiffeners comp...
29.4.2.12 Where metal cladding is in direct contact with the securing wire or reinforcing mesh, precautions should be taken to avoid the possibility of electrochemical corrosion that could result from direct contact between dissimilar metals under hum...
29.4.2.13 For certain types of application, e.g. close spacing of stiffeners, a rigid square mesh should be mechanically fixed over the outerline of the stiffeners, which is used as a substrate for the insulant; adjacent edges should be securely laced...
29.4.3 Gas flues, flares and exhausts [Go to Page]
29.4.3.1 The insulation system should be designed to maintain the gas temperature above the dew-point of the flue gas.
29.4.3.2 The insulation system used should be chosen taking into account the design of the flue and, in particular, the method of construction and the size and position of stiffening members incorporated to reduce vibration and provide structural stab...
29.4.3.3 The metal temperature of a carbon steel flue should be restricted to 460 C to avoid scaling (see 8.3.1). Precautions should be taken to protect the metal at higher gas temperatures, e.g. the use of heat-resisting alloy-steels instead of carb...
29.4.4 Metal chimneys
29.5 Flat and irregular surfaces (including machinery) [Go to Page]
29.5.1 General considerations
29.5.2 Pre-formed materials
29.5.3 Plastic composition
29.5.4 Flexible materials
29.5.5 Foamed in situ
29.5.6 Sprayed insulation
29.5.7 Loosefill insulation
29.5.8 Insulating concrete
30 Indoor finishes and their methods of application [Go to Page]
30.1 Sheet metal [Go to Page]
30.1.1 Untreated mild steel gives corrosion problems, and should therefore be protected, e.g. coated with zinc, aluminium, zinc/aluminium alloy, enamel, ceramic, plastics finishes. It should not be used unless both inner and outer surfaces are painted...
30.1.2 Corrosion-resisting alloy-steels are expensive, but they should be used where their resistance to corrosion and aesthetic appearance justifies the increased costs.
30.1.3 Aluminium, being relatively soft, should not be used for protection in areas which become exposed to substantial mechanical damage, particularly when it is applied over flexible insulating material. As flat sheets of polished aluminium tend to ...
30.1.4 When selecting the material for metal cladding, the compatibility of the metal with the insulation should be confirmed with the manufacturers. Direct contact between dissimilar metals should be avoided (see 8.3.4).
30.1.5 Where aluminium sheet is to be used under conditions of high humidity, e.g. in paper mills or in aggressive environments, surface-protected material for outdoor application should be used (see 31.1).
30.1.6 In flammable environments, all metal cladding and all wire netting at flanges, pumps, etc. should be bonded and earthed in accordance with BS EN 62305 (all parts) using stainless steel wire or bands.
30.1.7 As aluminium can be corroded by certain insulants, e.g. calcium silicate, the inner surface of the cladding should be painted with a protective coating or pipe-wrap tapes applied for corrosion protection, see 8.2.2.
30.1.8 The thicknesses in Table 7 should be used for general conditions.
30.1.9 Adjacent edges of metal sheet should be secured together by folded joints or by plain laps; for lapped joints, each sheet should cover the adjacent sheet by a minimum of 40 mm and the securing screws or rivets should be located at not greater t...
30.1.10 Arrangements should be made to secure the metal finish over the insulation or direct to the insulated surface so that “through” metal connection between the insulated substrate and the outer metal cladding is reduced to a minimum.
30.1.11 For long sections of vertical pipework, the cladding should be supported from attachments on the pipe (see 27.6 and 29.1.3). Adjacent sheets should be firmly attached to each other. Free-lapped joints should be fitted between the fixed points ...
30.1.12 For flat surfaces and for large irregular curved surfaces, the outer sheet metal should be secured to the insulated surface with studs or insulation support plates or expansion channels designed to accommodate differential expansion movement w...
30.1.13 The risk of polished metal finishes giving surface temperatures higher than those for non-metallic finishes under the same conditions, should be assessed and their use accepted or rejected accordingly..
30.1.14 To avoid direct contact between dissimilar metals, precautions should be taken against electrolytic corrosion for all materials (refer to 8.3.4). Galvanized or aluminized mild-steel sheets should be secured with cadmium-plated, galvanized or a...
30.2 Aluminium foils
30.3 Mastic and coating finishes [Go to Page]
30.3.1 The technique of application, e.g. by brush, hand or spray, should depend on size, location, risk of overspray and any possible need to permit evaporation of a solvent. The contractor should consult the manufacturer of the material on the detai...
30.3.2 A mastic and coating finish should be selected based on whether it is to be applied direct to the insulant, or whether it should be used in conjunction with open-weave glass-cloth, cotton scrim or canvas and the degree of protection required.
30.3.3 Water-based materials should be protected from frost during storage. They should not be applied when the ambient or surface temperature is below 5 C, or when freezing conditions are expected within 24 hours of application.
30.3.4 Solvent-based mastics and coatings can withstand freezing, but for best results they should not be applied at temperatures below 5 C. Most of them thicken considerably at low temperatures, rendering application by spraying particularly difficu...
30.3.5 Solvent-free materials, such as epoxies or urethanes, should be used where, for example, particular chemical resistance is necessary.
30.4 Hard-setting composition, self-setting cement and gypsum plaster [Go to Page]
30.4.1 General
30.4.2 Hard-setting composition
30.4.3 Self-setting cement
30.4.4 Gypsum plaster composition
30.5 Non-metallic sheet [Go to Page]
30.5.1 Where flexible plastics and elastomer sheets are adhered direct to the insulation; an adhesive recommended by the manufacturer should be used or they should be solvent-welded to themselves using a “solvent welding agent”. Adhesives or solvents ...
30.5.2 Where rigid plastics (PVC) sheeting is used, it is usually pre-curled to facilitate fitting over pipe sections and should not be less than 0.35 mm thick. Longitudinal and circumferential joints should be overlapped by 50 mm and longitudinal ove...
30.5.3 Ultra-violet cured GRP is a flexible product when first installed and hardens in the presence of UV light; it does not require the use of adhesive, but should be installed on to a dust free substrate.
30.5.4 Chloro-sulphonated polyethylene is a flexible product, which is wrapped around the insulation material and should be overlapped using contact adhesive and additional sealant.
30.5.5 If insulation is to be removed periodically, such as at flanges and manholes, it should be independently installed. The permanent insulation should be sealed effectively to the pipe or equipment.
30.5.6 Where aluminium foil tape1F ) is used on pipelines, especially those of small diameter, there should be sufficient clearance between the pipe and other equipment to permit the wrapping operation to be carried out. The tape should be spirally wr...
30.6 Textile fabrics [Go to Page]
30.6.1 Lightweight canvas and bands
30.6.2 Heavy fabric wrappings
31 Weather-resistant finishes [Go to Page]
31.1 Sheet metal [Go to Page]
31.1.1 The recommendations given in 30.1 apply also for sheet metal finishes for outdoor installations, but protective measures should be taken to prevent electrolytic corrosion. Ingress of water should be prevented and the metal itself should be suit...
31.1.2 If the normal overlap for profiled sheets with a sealant, as in 31.1.1, does not adequately avoid water penetration, arrangement should be made to retain the lapped surfaces in close contact without penetrating the sheets, e.g. with banding.
31.1.3 If the metal cladding is exposed to wide variations of atmospheric temperature, provisions for thermal movement should be made and “through” metal connections with the insulated substrate should be restricted (see 29.1.3, Figure 6 and Figure 7).
31.1.4 To prevent aluminium sheets developing irregular white areas of oxide film after a period of exposure to outdoor weather conditions; material that has received a chemical or electrolytic treatment should be used, e.g. anodized, surface treatmen...
31.1.5 Where exposure to high wind is probable, the cladding should be retained by banding with all overlaps mechanically secured. Support should be designed to accommodate suction forces.
31.2 Synthetic sheet materials
31.3 Non-metallic sheet
31.4 Self-setting cement [Go to Page]
31.4.1 Self-setting cement is not impervious to water and possesses low flexibility, therefore where it is exposed to outdoor weather conditions without further protection, it should be protected with a coating.
31.4.2 Where the porosity of self-setting cement is reduced by the application of surface coatings, the cement should be fully dry before weatherproofing coatings are applied to avoid any possibility of the coatings blistering.
31.4.3 A continuous layer of cement should be applied over large areas unless high differential movements are expected. Covers over projecting stiffeners should be used to take up expansion movement; for greater differential temperatures, the need for...
31.5 Weatherproofing compounds [Go to Page]
31.5.1 General considerations
31.5.2 Direct application over insulating material
31.5.3 Application over a finish of hard-setting composition
31.5.4 Application over a finish of self-setting cement
32 Ultimate treatment of finish painting
33 Inspection and testing of the insulated system materials before and during installation
34 Insulated pipe support inserts (IPSI) and insulated duct support inserts (IDSI) [Go to Page]
34.1 General
34.2 Insulated pipe support inserts (IPSI) for building services applications [Go to Page]
34.2.1 Pipe supports inserts are installed between the pipe and the pipe clamps to maintain thermal performance and the integrity of the vapour barrier.
34.2.2 Although high-performance thermally efficient pipe inserts should be prioritized to minimize thermal bridging and energy loss, there are situations where these solutions do not provide adequate structural support, particularly under high-load s...
34.2.3 When load-bearing insulated pipe support inserts are installed on stainless steel pipework, a sacrificial aluminium foil barrier should also be applied. To provide protection, aluminium foil of not less than 0.06 mm thickness should be applied ...
34.2.4 The cladding detail should be agreed at early stages and the load-bearing insulated support insert should be pre-clad with the specified weatherproofing material to allow for both insulation and cladding to run continuously through the pipe sup...
34.3 Refrigeration applications
34.4 Insulated duct support inserts (IDSI) [Go to Page]
34.4.1 General
34.4.2 Rectangular ducts
34.4.3 Circular ducts
Section 5: Post-installation inspection and maintenance
35 Inspection and maintenance [Go to Page]
35.1 General
35.2 Inspection, maintenance and sealing of insulation containing asbestos [Go to Page]
35.2.1 Inspection and maintenance
35.2.2 Encapsulating or sealing
35.3 Stripping old insulation containing asbestos
36 Guarantees
Annex A (informative) Adhesives [Go to Page]
A.1 Service properties [Go to Page]
A.1.1 Application characteristics
A.1.2 Temperature limits
A.2 Curing [Go to Page]
A.2.1 Solvent-based adhesives
A.2.2 Water-based adhesives
A.2.3 Chemically curing adhesives
A.2.4 100% solids adhesives
A.3 Types and typical properties [Go to Page]
A.3.1 General
A.3.2 Bitumens
A.3.3 Epoxy-resins
A.3.4 Natural rubber
A.3.5 Neoprene-phenolic
A.3.6 Nitrile-phenolic
A.3.7 Emulsion polymers – PVA etc.
A.3.8 Styrene-butadiene-based (SBR) cements
A.3.9 Silane-modified polymer technology
A.3.10 Polyurethanes
A.3.11 Silicones
A.3.12 Bitumen-polyurethanes
Annex B (informative) Water vapour pressure and the relation to water vapour barriers
Annex C (informative) Water vapour diffusion resistance ratio (µ value)
Annex D (informative) Vapour barrier materials
Annex E (informative) Finishing materials [Go to Page]
E.1 Sheet materials
E.2 Synthetic sheet materials
E.3 Liquid solutions and dispersions
E.4 Polymer coatings
E.5 Dry mixtures brought to paste consistency with water
E.6 Woven or knitted fabrics [Go to Page]

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25/30499772 DC BS 5970 Installation of thermal insulation systems on pipework, ductwork and associated equipment for all applications in the temperature range of −40 °C to +700 °C .Code of practice, 2025

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25/30499772 DC BS 5970 Installation of thermal insulation systems on pipework, ductwork and associated equipment for all applications in the temperature range of −40 °C to +700 °C .Code of practice, 2025

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please select your company type below: