Gasket
Types and Durability
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Description Gasket |
Expected Lifespan (Years) |
Adjustment Factors
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External
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| Thermoplastics (PP, PE, PS, PVC)*
Flexible PVC specified in ASTM C 509 and C 864,with test certification for compression set & stress relaxation, weatherability & UV resistance, heat aging, fluid resistance. |
10
|
1st stage adjustment factor:
In industrial areas (heavy polluted): -15% years In urban areas: -10% years In suburban areas: -0% years 2nd stage adjustment factor: West or south orientation: -10% years Applied to reseal existing joint: -15% years. Test certificate from approved local testing authority (as specified in SS 212:2000 for glazing material) : +15% years |
| Uninsured. Thermoplastics gaskets not specified in ASTM C 509 and C 864 and without test certification. |
< 10
|
|
| Thermoset Rubber/ Elastomer (Silicone, EPDM, Neoprene, NBR).**
Neoprene (Chloroprene Rubber) as specified for glazing material and to ASTM C 509 and C 864,with test certification for compression set & stress relaxation, weatherability & UV resistance, heat aging, fluid resistance. |
20+
|
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| EPDM Rubber ** as specified for glazing material and to ASTM C 509 and C 864,with test certification for compression set & stress relaxation, weatherability & UV resistance, heat aging, fluid resistance. |
20+
|
|
| Silicone Rubber and to ASTM C 509 and C 864,with test certification for compression set & stress relaxation, weatherability & UV resistance, heat aging, fluid resistance. |
20+
|
|
| Uninsured. Thermoset gaskets not specified in ASTM C 509 and C 864 and without test certification. |
< 20
|
|
| Thermoplastic Elastomer – TPE (Santoprene, Kriburge, Evoprene, Forprene, Alcryn).TPE as specified in ASTM C 509 and C 864, with test certification for compression set & stress relaxation, weatherability & UV resistance, heat aging, and fluid resistance. |
20+
|
|
| Unclassified. Thermoplastic Elastomer gaskets not specified in ASTM C 509 and C 864 and without test certification. |
< 20
|
Combination of adjustment factors (1st stage and 2nd stage) should be added to obtain the durability values. Refer to durability calculator.
Notes:
* PVC is still fairly popular amongst fabricators in Singapore, because of its economic fit. This material loses its flexibility over time as it plasticizer migrate out of the polymer structure. The end result is in effective sealing performance due to the migratory process where PVC starts to harden and crack. PVC is also incompatible to PC (polycarbonate) used widely for skylight application as plasticizer migration and attack cause embrittlement craze or stress cracking.
** Both Neoprene/ CR and EPDM are not compatible to silicone sealant as they may cause silicone discoloration, loss of silicone seal and adhesion.
The compatibility of gasket material and other aluminium finishes, glass, sealant or other glazing material shall be confirmed with the manufacturer.
Test
Good Compression Set (ASTM-395B) and Compression Stress Relaxation (ISO 3384A)
Readily deforms under load and recovers to original shape after load is removed. Compression set is defined as the percent of set or permanent deformation that a material experiences when a specific load is removed from the specimen.
Weatherability and UV resistance (ASTM D412)
Evaluated by change in appearance and retention of physical properties after prolonged exposure to ultraviolet radiation. A typical method for monitoring appearance is the total colour change (D E). A D E of 3 or greater represesnts a change that is perceptible to human eye and this value is used in many products specification.
Heat Aging (ASTM D865)
Maintains its properties after exposure to heat over period of time. Usually measured in terms of change in hardness, elongation and tensile strength.
Fluid Resistance (ASTM D471)
Material should stay soft with age and delivers superior resistance to acids, bases, cleaning agents, and pollutants.