• Introduction
• Background
  • History
  • Process Plant
  • Recycling Sealant
• Get the Best
  • Gel Time
  • Sealant Condition
  • Temperature
  • Orientation
  • Casting Condition
  • Vacuum
  • Using Test Rings
  • Test Ring Chart
  • In Conclusion
• Standards
  • Review
  • Proposed Changes
  • MIL-1-1756C
  • Suppliers
• FAQs
• Links
• Contact

Check that correct temperature is being applied for curing.

There are a good number of aging hot cure tanks in use today that have no means of circulating the hot water during the cure cycle. This can lead to cold spots within the tank and particularly within the batch of components. It is also possible that the heat input could be down for a variety of reasons such as caking of heating elements etc.

Temperature is a fundamental part of the impregnation process. No matter how good a sealant may be, if the heat is not there, it will not cure. Its mechanisim is such that it's either liquid or solid. The cure takes place in seconds but that short period is critical and the heat must be maintained to achieve polymerization. As indicated earlier, failure for the sealant to cure when first heated, it is then unlikely to cure even at a higher temperature.

First ensure that the heating is adequate for the load of components going through the plant. If not, reduce the load accordingly. Maintaining a large load and extending cure times does not work. Run the water cure at maximum temperature and ensure that the heat loss during the cure cycle does not drop below 90^ºC. In terms of heat circulation, fit a powerful centrifugal pump with filter or other device. Do not fit aeration as this removes heat.

Your tank should be regularly checked with a portable digital immersion probe in a number of areas, especially close to the bottom, and compared with the resident sensor.