Insulation of Pipes
| Insulation without Finish | Insulation should not be left without finish in service. The methods of applying unfinished material described in this guide refer only to situations where the finish is to be applied separately. |
| Foil Faced | For internal use where a pre-applied, semi-decorative vapor barrier is required. Care should be taken where impact damage is likely, e.g. at low-level installation. |
| Sheet Metal | For external use where a separately applied, weatherproof impact resistant finish is required, or for internal use where mechanical strength is needed, e.g. low-level pipe work in boiler houses. |
| Polyisobutylene Sheeting (PIB) | External use where a flexible weatherproof, sheet finish is required and likelihood of mechanical damage is minimal. |
| Glass Cloth (or scrim) and mastic | External use to provide a reinforced, separately applied weatherproof finish. Chemical resistant grades are also available. |
| Hard-setting composition | A hard, permanent, impact resistant finish for internal use, e.g. in boiler houses. |
| Self-setting cement | A hard, permanent, impact resistant finish for external use or for internal use where no means of drying out exists. Normally finished with mastic when used outside. |
| Canvas and paint | For internal use where a separate vapor barrier is preferred. |
2.1.1 Note to Specifications
When preparing specifications for the insulation of piping, it is important to ensure that the insulation is suitable for the temperature and conditions, and that the covering is within the manufacturers stated range of surface temperatures. Insulation thicknesses are not included in this guide, as they must be calculated to meet the appropriate operating conditions.
2.1.2 Multi-Layer Applications
Where the required insulation thickness is greater than that in which the selected product is available or when specification limits individual layer thickness, it will be necessary to apply the insulation in more than one layer. In such cases an additional clause should be inserted in the specification as indicated below. Because of the standard pipe sizes available, it is not always possible to obtain preformed insulation to fit precisely on a previous layer of insulation. A slightly smaller size can sometimes be compressed to fit without leaving a longitudinal gap. A small fillet cut from the same material should be used to fill any unavoidable gaps. Alternatively, an oversized section can be trimmed to ensure a snug fit. When it is necessary to fit Stonewool preformed pipe sections in more than one layer, the first layer must be fitted close to the pipe with joints butted closely together and secured with binding wire or metal bands. Subsequent layers should be fitted in a similar manner ensuring that the joints in adjacent layers do not coincide.
Model Specifications
2.1.3 Without Finish
Pipe work shall be insulated with Isover Stonewool preformed pipe sections of suitable thickness, ensuring that all joints are well butted together, secured to the pipe with metal bands (lacing wire may be preferred in certain applications, e.g. under mastic finish) at maximum 450mm centres with one band not more than 50mm from the end of each section. Bends to be insulated with carefully mitred segments of Stonewool preformed pipe sections fitted closely to the pipe and suitably banded in position. All fittings to be insulated with the same thickness of insulation.
2.1.4 With hard-setting composition finish - for internal use.
Pipe work shall be insulated with Isover Stonewool preformed pipe sections of suitable thickness, ensuring that all joints are well butted together. Bends to be insulated with carefully mitred segments of Stonewool preformed pipe sections. All fittings to be insulated to the same standard and finish as adjacent pipe work. The insulation to be held in place with 1,0mm lacing wire and secured in place with 25mm X 1,0mm galvanized wire mesh pulled tight to ensure close contact with the pipe. Over this a 12mm layer of hard-setting composition (or thickness as specified by the composition manufacturer) shall be applied in two coats and trowelled smooth. After complete drying out a coat of size shall be applied and two coats of heat resistant paint.
2.1.5. With self-setting cement finish - for internal or external use.
See application detail as specification 2.1.4 except that self-setting cements should be applied to give a thickness of 6mm (or thickness as specified by the manufacturer) and trowelled smooth. Where painting is required, the cement must be thoroughly dried before applying alkali-resistant primer and two coats of alkali-resistant paint.
- Note: (a) For external use - the application of a final layer consisting of scrim embedded in mastic is required instead of the paint finish.
- Note: (b) The application of self setting cement over Stonewool preformed pipe sections is greatly facilitated by a skin coat which forms a key for the self-setting cement.
2.1.6. With painted canvas finish - for internal use.
Pipe work shall be insulated with Isover Stonewool preformed pipe sections - Canvas covered, in suitable thickness ensuring that all joints are well butted together. Bends to be insulated with carefully mitred segments of Stonewool preformed pipe sections. All fittings to be insulated to the same standard and finish as adjacent pipe work. The longitudinal and circumferential canvas overlaps to be securely stuck down with suitable adhesive and neatly smoothed out. Two coats of heat resistant paint to be applied.
2.1.7 Foil-faced - for internal use
Pipe work shall be insulated with Isover Stonewool preformed pipe sections - Foil faced, in suitable thickness ensuring that all joints are well butted together.
Longitudinal overlaps to be securely stuck down with suitable matching tape or by use of a proprietary self adhesive system. Butt joints to be covered with suitable self-adhesive tape not less than 50mm wide. Bends to be insulated with carefully mitred segments of Stonewool preformed pipe sections, and all joints covered with suitable self-adhesive tape. All fittings to be insulated to the same standards and finish as adjacent pipe work.
2.1.8 With Polyisobutylene (PIB) finish - for external use.
Pipe work shall be insulated with Isover Stonewool preformed pipe sections - PIB covered, in suitable thickness ensuring that all joints are butted together. Longitudinal overlaps to be securely stuck down by welding together with white spirit or other suitable solvent. Circumferential butt joints to be overlapped with PIB sheeting not less than 50mm wide and securely stuck with white spirit or other suitable solvent. Bends to be insulated with carefully mitred segments of Stonewool preformed pipe sections covered with PIB sheeting. All fittings to be insulated to the same standard and finish as adjacent pipe work. All overlaps must be arranged to shed water and special care taken when sealing joints so as to prevent the ingress of moisture. Solvent manufacturer’s instructions must be carefully followed.
- Note (a): Plain sections may also be used and the PIB sheeting applied on site.
- Note (b): The PIB sheeting should have a minimum thickness of 0,8mm.
2.1.9 With glass cloth (or scrim) and mastic finish for internal or external use.
Insulation to be applied as detailed in Specification 2.1.3 Mastic then to be applied over insulation in accordance with the manufacturers instructions. The glass cloth (or scrim) should be cut to size, bedded into the mastic, and smoothed to remove all wrinkles. A further coat of mastic should be applied when the first coat is dry.
Note:
Choice of mastic will depend on whether the application is internal or external. The glass cloth should be of sufficiently open weave to allow penetration of the mastic.
2.1.10. With sheet metal finish - for internal or external use.
- Insulation to be applied as detailed in Specification 2.1.3
The sheet metal shall be formed to fit tightly over the outer circumference of the insulation with a longitudinal overlap of not less than 40mm, the outer part of the overlap to be secured with self-tapping screws or rapid fix rivets of the appropriate type at centres of not more than 150mm or, where appropriate, secured with metal bands of suitable type and dimensions. Circumferential overlaps shall not be less than 40mm and secured with self-tapping screws or easy-fix rivets, not less than four equally spaced.
At suitable intervals, provision should be made to accommodate expansion and contraction. All joints must be lapped weather wise in order to shed water. Where exposed to weather, or where there is risk of liquid spillage onto the surface, all joints shall be sealed with flexible sealant. All bends and fittings to be covered with matching sheet metal tailored to fit and adequately sealed where necessary. All fittings which may require periodic attention, e.g. valves and flanges, should be fitted with pre-insulated, purpose designed boxes, which can be easily removed and replaced.
Note: Where sheet metal cladding is applied over vapor sealed insulation, special care must be taken to avoid puncturing the vapor seal. Screws and rivets should not be used.
