Product Overview

BenefitsDesign Features Downloads & Links

The HMT Flex-A-Seal Secondary Seal is one of the most economical and effective types of secondary seals available. Easily installed and maintained, the HMT Flex-A-Seal’s ability to meet or exceed stringent gap specifications for secondary seals has earned its approval from governmental regulatory agencies throughout the U.S. and European markets.


No gapping

Sized specifically to each tank and constructed from custom-hardened stainless steel to ensure tension will hold up year after year, the HMT Flex-A-Seal will maintain a tight seal over time.

Long life

All HMT pressure-application components are made from custom-hardened stainless steel to prevent yielding under load, ensuring spring longevity and long-lasting seal performance.

Excellent weather shedding

The HMT Flex-A-Seal features a wiper tip that conforms tightly to the tank shell, minimizing ingress of rainwater into the stored product.

Capable of being installed in service

Bolt-on design means no hot work is required.

Design Features

Hardened-steel pressure componentsContinuous vapor barrier under compression platesNarrow compression platesBest-in-class vapor barriersSized to fit the tank

Hardened-steel pressure components

Custom-hardened steel will not fatigue over time, maintaining proper sealing pressure against the tank shell and preventing gaps over the life of the seal.

Continuous vapor barrier under compression plates

The HMT Flex-A-Seal utilizes continuous fabric vapor barrier under the compression plates, ensuring far better seal integrity than systems that rely on gaskets between plates.

Narrow compression plates

The HMT Flex-A-Seal has narrow compression plates for excellent flexibility and conformation to tank shell deviations, but also to reduce wiper tip wear versus compression plate systems with wider plates, which concentrate tip pressure at the overlaps and create uneven wear.

Best-in-class vapor barriers

Premium fabric options ensure optimal product compatibility and life span, even including flame-retardant PTFE options compliant with DIN 22118 standard. We offer a variety of fabric choices depending on your service requirements. Our standard PTFE fabrics are laminated and unsurpassed in terms of durability, impermeability, and service life. HMT’s fabrics will wear extremely well in even the most aggressive services.

Sized to fit the tank

All tank shells are not alike, and it’s critical that seals are designed to handle unique rim-space requirements. HMT’s engineering and manufacturing automation allow each seal to be manufactured to fit the specific rim space and/or verticality data provided by the purchaser, ensuring optimal performance and mitigating the chance of operational issues over time.

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