Policy and Procedure

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Quality Policy

Dual Seal Glass Limited is a manufacturer of hermetically sealed Insulated Glass (I.G.) Units. A proven leader in its field. Dual Seal Glass Limited manufactures products for both commercial and domestic use within the UK and in a rapidly expanding commercial European export market.

The company is committed to providing a product which meets the requirements of the European Standard BS EN 1279, British Standard Institute Kitemark Scheme and customer's requirements.

This commitment to Quality is constantly strived for through the implementation and maintenance of the Quality Management System EN ISO 9001 - 2000. This is achieved through a system of Internal Quality System Audits, Management Reviews and continuing assessments by the British Standards Institute client managers.

Quality objectives are set as the result of Management Reviews.

Specific Quality Objectives are also actioned through changes in current legislation or customer requirements. Documented procedures reflect such actions and the results of such actions are communicated to all employees.

Through an ongoing Training and Quality Awareness Programme all employees are constantly reminded of the Quality Standard each individual is expected to maintain. All new employees are made aware of the Quality Standard requirement on their induction, and are closely monitored through each stage of their training programme.

The Quality Policy of Dual Seal Glass Limited has been defined by Senior Management and as such the Managing Director of Dual Seal Glass Limited bears the ultimate responsibility for the functioning of the Quality Programme.

This Quality Policy is reviewed at Management Reviews to ensure its continuing suitability and effectiveness in helping to maintain and improve upon the scope of the company's activities in its pursuit of excellence.


Handling and Storage

Upon delivery of the glass, check marks and labels on the crate, pack or glass to ensure compliance with the specification. The edges and corners of glass and double-glazed units are especially vulnerable during handling, storage and installation. Inspect the cut edges of the glass for excessive flaws such as shells or feathers that can compromise the strength and mechanical performance of the glass.

Check all surfaces for any signs of mechanical damage or etching. Particular care is necessary as edge or surface damage may cause subsequent unexpected failure.

Glass that is not stored safely can present considerable risk of injury.

Never stack glass panels horizontally.

Store panels on edge at an angle of 3° to 6° from the vertical, with sufficient lateral support to prevent bowing, in a clean dry, ventilated place, avoiding direct sunshine and other sources of heat. Set the glass panes on strips of wood or other soft material, to avoid contact with hard materials such as metal, stone or concrete. Avoid contact with alkaline materials such as lime and cement. Delivery, handling and site storage methods must be agreed for each site.

Any form of factory applied protection, such as cork pads or shrink-wrapping, must not be removed until the glass is ready for installation. When the packaging has been removed, the glass must be covered to prevent the ingress of dust and grit that may cause subsequent scratching.

Glass is not normally considered corrodible by contact with water providing it is allowed to dry properly.

However, if water is allowed to remain in contact with the glass for extended periods it can become alkaline and will attack the glass surface. If not stored properly water can penetrate between panes of stacked glass by capillary action; this moisture is then trapped between the panes and will tend not to dry naturally, eventually "welding" the glass sheets together.

If any moisture or condensation is apparent between the panes of stacked glass, separate immediately and dry thoroughly, otherwise permanent staining may result. Re-stack in a more suitable location in accordance with the advice provided above and the recommendations in conjunction with the current code of practice for glazing and buildings.

Carefully inspect all glass before installation.


General considerations

Prior to installation on site, general preparatory work must ensure that the openings are ready for glazing.

Check that all required glazing materials are available on site prior to commencing glazing along with all appropriate equipment.

Ensure that frame fixing is complete and that the frames and channels are clean, dry and free from obstructions. Ensure that all glazing materials are compatible with each other and suitable for the framing system. This is particularly important for double-glazed units as certain solvents that are contained in certain glazing materials can attack the edge-seal.

Consult the relevant manufacturers for advice and instruction on compatibility. In order to reduce the risk of breakage or damage after installation, identify areas of glass by hanging narrow streamers from the framing. Do not mark or fasten identification directly to the glass. Remove all supplier packaging labels at the time of glazing. Certain coated glass types are not suitable for use in single glazing, consult the relevant product information in the manufacturer's current literature.

For optimum performance and minimum solar factors, solar control glasses should be the external pane of double-glazed units. It is generally preferable to locate the solar control coating on face 2 of a double-glazed unit although some glass types may be glazed with the coating on face 1.

Glasses with low-emissivity coatings can be located on either face 2 or face 3 without unduly affecting performance. It is usual for the low-emissivity coating to be on face 3 especially when a solar control glass with a coating on face 2 is being used. Certain coated glasses must be edge-stripped before they are assembled into double-glazed units to ensure good adhesion between glass and sealant.

Double-glazed units constructed with different glass types to each pane must be installed with the correct glass to the external or internal pane as appropriate to the application. Failure to do so may affect appearance, safety and performance. If in any doubt, consult Dual Seal Glass.


Self Cleaning Glass

The specialist characteristics of these coatings require specific product compatibility and specialist glazing techniques.



Any modification to the Dual Seal/Dual Therm/Dual Span range of double glazed units after receipt (eg. application of films, application of profiles) will invalidate our guarantee.

We do not recommend the use of edge tapes with sealed double glazed units as this practice can lead to the premature failure of the sealed unit due to water being trapped between the tape and the edge seal. However, if we are asked to provide such units for handling or identification purposes we stipulate the tape must be removed prior to glazing.

DUAL SEAL GLASS LTD will not be reponsible for any of the costs involved in replacing units that have found to have failed and are found to be still edge taped, the cost of the replacement units, deglazing, reglazing and any other associated costs will have to met by others.

DUAL SEAL GLASS LTD guarantees against defects in materials causing condensation or the formation of deposits of dust inside the double glazed units, thus impairing their optical quality, for a period of 5 years from the date of production.

This warranty is only valid if our instructions regarding installation and glazing of the double glazed units are fully complied with see Glazing Section.


Our warranty does not apply to:

  • Broken or cracked units
  • Glazing which has not been specified, transported, stored, handled, installed, cleaned and used in accordance with our directions.
  • Replacement glazing, after the warranty period for the original glazing has expired.


Warranty certificates are available on request.