Preventing Transformer Failures with Transeal® Transformer Gaskets

study by the Hartford Steam Boiler, a leading equipment breakdown insurance provider, reveals that the number one cause of transformer failures is failure of the transformer insulation. The study points out that there are four factors that are responsible for insulation failure: pyrolysis (heat); oxidation; acidity; and moisture.

Because they help prevent the degradation of transformer insulation, Transeal® gaskets described in this blog are a key element in any strategy to reduce and prevent costly transformer failures. Here is how they work:

Within a transformer, oil is used as an insulator and as a means to transfer heat generated in the windings and core towards the tank walls and radiators. When a transformer leak occurs, the connections, bushings and parts of the windings can become exposed to air and oxidize. In addition, moisture may infiltrate through the leaking gasket causing loss of the transformer oil’s integrity and deterioration of the oil’s ideal physical properties. This conspiracy of degrading and depleting the transformer oil results in the imminent increase of the temperature in the windings, and may lead to a catastrophic failure.

The costs of transformer failures

In addition to causing a costly equipment loss, failure of a transformer gasket can result in damage to the environment. Any oil secretion from a transformer can potentially contaminate the ground, tainting soil and groundwater as well as posing a risk to wildlife and humans. Contaminated soil and groundwater is costly to assess and cleanup, adding to the cost of the failure. In addition to the treatment costs, fines may also be imposed by regulatory bodies such as the Environmental Protection Agency (EPA).

Reducing and preventing transformer failures: Transeal® transformer gaskets

Nitrile Rubber (NBR) is the preferred solution to resist petroleum-based fluids, such as transformer oil.  Even the most aggressive oils in use today have little effect on this revolutionary compound. Transeal® performs optimally at a wide range of service temperatures and possesses very good resistance to alkalis and acids. Transeal® PREMIUM GRADE Nitrile from American Biltrite provides the best sealing solution for transformer gasketing applications.

Engineered specifically for use in electrical transformers, Transeal® meets or exceeds M409E specifications. Gaskets produced from Transeal® maintain stability and help prevent dangerous transformer explosions and fires.

Transeal® offers the following advantages:

  • Exceptional tensile strength with strong resistance to applied loads, system blowouts, or vacuum.

  • Unrivaled compression set values. 9 percent represents a typical test result for Transeal® gaskets, meaning that the material retains 91 percent of its original form. Standard nitrile and cork option can run from 45 to 75 percent.

  • Exceptionally low oil swell (12 percent) - silicone-based oils (the most aggressive oils in use today) have little effect on Transeal®

  • Superior conformability. Transeal® gaskets are recommended when the joint has recesses or expansion limiting grooves – Transeal® is elastic enough to conform to imperfections on the sealing surface.

  • Transeal® PREMIUM NITRILE is not porous, hence it does not require a secondary sealant or paint.

  • Superior service temperature range. Transeal® gaskets will withstand high and low temperatures. Transeal® gaskets can also be easily removed and replaced in various temperatures.

What are the properties of Transeal® gaskets?

Transeal® material has a specific gravity of 1.17 and a hardness (Shore A) of 65. The material has a tensile strength of 2400 psi and an ultimate elongation percentage of 500.

Gaskets produced from Transeal® will service a cold temperature of -30°C min. Compression set for 70 hours at 100°C is 16 percent maximum, with a temperature range (general guideline) of -29°C (-20°F) to 93°C (200°F).

Heat aging for Transeal® from the ASTM D573 standard is as follows:

  • 3 weeks @125°C

  • Changed hardness: 18 points

  • Tensile: 2% max.

  • Elongation: -66% max.

  • (all values nominal)

Oil aging (#3) from the ASTM D471 standard is as follows:

  • Voltesso 35 oil

  • Changed hardness: 3 points

  • Tensile: -60% max.

  • Elongation: -78% max.

  • Mass: 10%

  • Volume: 12%

  • (all values nominal)

Is Transeal® an approved material?

Transeal® conforms to Hydro Quebec transformer gasket specification SN-14.1. The material is also approved and used by the Tennessee Valley Authority and found to be superior when compared to other products. Transeal® is engineered specifically for electrical transformers and meets or exceeds GE and ABB M4094E specifications.

How can I obtain Transeal® transformer gaskets?

CRG services electrical transformer applications by manufacturing and supplying gaskets made from Transeal® material. These gaskets are made using the latest production and fabrication technology. We can produce Transeal® transformer gaskets in both large or small order volumes. CRG Transeal® transformer gaskets can be custom produced to suit almost any transformer design and type.

If you are seeking to reduce or prevent costly transformer failures, the CRG sales team will be pleased to review your needs and discuss the advantages of Transeal® gaskets.

For further information on Transeal® transformer gaskets from CRG, please contact our sales department at