H-Seal® Metal Gaskets

Developed for Small Footprint UHV

Cutaway of gold H-Seal.

Submit your designs and specs

Narrow, Efficient Profile – Can Be Used in Tight Spaces

  • Low compression force—smaller fasteners required
  • Self-limiting—cannot be overtightened
  • Self protecting—won’t scratch
  • Robust—easy to use
  • Guaranteed 1 x 10-11 leak rate
  • 100% reliable—100% yield, guaranteed!

Full section cutaway assembly of a two CF flanges crushing a CF gasket to completion and demonstrating that the HiRim raised perimeter sits without interference in the free space of the gland.

Typical Application: 500cc Stainless Steel Ampoule with OFS Copper H-Seal

Typical H-Seal application, showing assembly steps and cross section of H-Seal

Cut aways showing positive dead stop of H-Seal.

H-Seals are space-saving, easy to handle, easy to install and easy to remove. They also cannot be over-tightened. The H-Seal itself provides a positive dead-stop, or you can specify gland-to-gland mating. The gland can be used over and over with no loss of performance.

H-Seals: Reduce Your Design Envelope

Ideal for Applications Where Space is Limited

These images show a comparison between an H-Seal and a standard CF3.375 metal gasket. Note the significantly smaller footprint of the H-Seal vs. the CF gasket. Also notice that lower compression forces allow for smaller fasteners and a thinner lid.

Narrow, efficient profile of H-Seal takes 50% less space, and smaller fasteners mean smaller bolts, which also save weight and space.

Two Basic Profiles: Zero Clearance or Gap H-Seals

Sizes up to 60″ OD

Two configuration of H-Seals, gap, which forces the flanges to bottom on the seal or zero-clearance allows the flanges to bottom on each other.

Interchangeable with O-Rings

The H-Gland allows interchangeable use of metal H-Seals or elastomeric O-rings. Therefore, a single flange or base can be used for both elastomeric and metal-sealed applications. This also allows elastomeric seals to be used for intermediate production testing, with the final stage being H-Seal installation.

No Cost License to manufacture your own H-Glands.

H-Seals and H-Glands are based on patented and proprietary technology developed and owned by Bostec Engineering. Purchasers of H-Seals are given a no cost license to manufacture their own H-Glands. To obtain full manufacturing specifications and dimensions, simply call or email Bostec. We will send your no cost license and H-Gland manufacturing guidelines. We will also provide free over-the-phone consulting for your machine shop on producing the H-Gland.

H-Seals are interchangeable with elastomeric O-Rings.

Engineering and Usability Benefits of H-Seals

1. Self-Aligning

H-Seals are inherently self- aligning. This eliminates the need for retainer rings or other alignment devices. The raised shoulder guides the H-Seal and mating flanges into proper position while simultaneously protecting the knife edge from damage.

2. Positive Stop Prevents

H-Seals work by conforming a soft metal seal to a sharp knife edge. The sharp tooth angle keeps penetration forces low. The tooth remains sharp throughout the entire penetration process—the more force applied, the tighter the seal. The H-Seal itself acts as a positive stop so there is no risk of over-tightening. The H-Gland can be used over and over with no loss of performance.

3. H-Seals Tolerate Significant Misalignment

Misalignment of up to 10% of the H-Seal OD is tolerated with no loss of performance or seal integrity

4. Recessed Critical Surfaces

Critical sealing surfaces on both the H-Seal and H-Gland are recessed and protected from damage.

Both the flange and H-Seal can be placed on assembly tables without the knife edge or seal surface being damaged. This makes H-Seals easy to handle in production environments.

Many Shapes Accommodate Different Design Requirements

Illustration showing various designs allowing accommodation of special design needs.

Choose the Right Shape for Your Design

Zero-clearance H-SealsZero-clearance H-Seals

Standard profile sizes from 0.300″ to 32″ OD. Or let Bostec develop custom shapes to accommodate your special requirements.

Deep-Well H-Seals

Deep-Well H-Seals are often used in horizontal installations where extra positioning or holding assistance is needed.

End-Cap H-Seals

End-Cap H-Seals are used as simple mechanisms for 100% positive, leak-tight closure.

Reverse H-Seals

Reverse H-Seals switch the knife edge to the outside. This minimizes dead volume or provides a smooth shape on the ID surface.

H-Seals–– 100% Precision Machined

Most components in any modern UHV process are precision machined to tight tolerances with highly polished surface finishes. Your gaskets should be no different! Precision gaskets fit properly, are 100% reliable and do not contaminate with unwanted burrs, abrasive contaminants or manufacturing debris.

Bostec H-Seals are machined on all surfaces and are completely free of burrs. Gasket faces have precise machining grooves in an annular ring pattern to ensure the knife edge seats into the gasket.

Surfaces are less than Ra 0.6 (circular) and delivered “as-machined”—not polished or otherwise modified post machining. No abrasives are used.

Our inpection process ensures no radial scratches are visible at 10X magnification, and the gaskets are free from surface inclusions and other blemishes.

In the world of super-UHV, the cost of a single failed gasket is 1000X the cost of the gasket itself. It makes no sense to use inferior gaskets and risk failure.

Smooth surfaces and fully swept flow path minimize trapped particles.

Bostec CF Gaskets Magnified

20X DN63 Copper
30X DN63 Ni 200/201