Sole-Source: Bostec Engineering, Inc.

As far as our awareness extends, Bostec Engineering stands out as a one-of-a-kind company in both the United States and Europe, specializing in the production of static UHV and UHP metal seals. Bostec serves industries that include outer space, nuclear fusion, particle accelerators, semiconductor manufacturing and deep-well oil exploration.

Bostec specializes in integrating UHV metal seals into our customers’ products using the smallest possible footprint and requiring the lowest force requirements to achieve the smallest overall package size and weight. We have extensive expertise with nickel, copper, aluminum, titanium, niobium, ceramics, explosion bonded metals, NEG coatings, and more.

Bostec specializes in difficult applications where the UHV imperative is high and space and weight are limited, such as NASA DaVinci spaceship to Venus, CERN’s High Luminosity 13.9 TEV accelerator, numerous fusion projects, SLB deep well drilling applications, to name a few.

What sets Bostec apart is our comprehensive in-house capabilities, encompassing the following:

For the most challenging projects, Bostec has the in-house machining capability of producing both the UHV metal gaskets and the surrounding housing or flanges, allowing Bostec to provide our customers with a matched set of housings and gaskets, which we guarantee to perform 100% to “by-the-book” UHV standards.

  1. Bostec manufactures an extensive array of knife-edge and diamond metal seals, featuring proprietary designs, including patented and patent-based variants, all manufactured inhouse from 0.5” to 60”.
  2. Multi-sided metal seals: Bostec uniquely offers off-round and multi-sided knife edge metal seals in sizes from a few inches in cross section to 36” x 36” and beyond.
  3. Matched-sets: We also produce accompanying glands (flanges), and ship them to our customers as a matched-set that includes the metal seal, with the matched set guaranteed to achieve true UHV levels (10-10 torr / 10-11 atm-cc-He/sec).
  4. Our specialized force and UHV testing laboratory is equipped to tackle the distinct challenges presented by our customers’ prototype UHV metal seals. Through empirical force testing, we fine-tune knife-edge shapes to minimize force and footprint, pinpoint optimal UHV achievement points, all while ensuring reusability.
  5. Bostec manufacturers its products in-house and sells directly to the end user, usually OEMs like MKS and Intel or government research organizations like NASA and CERN. Bostec does not broker products produced by others, or sell through brokers or dealers.
  6. Where possible, Bostec sources all raw materials directly from specialty mills and made to our recipe, ensuring absolute certainty of material origin and composition.

X-Energized diamond-seals as direct replacements for C-seals:

C-seals are notoriously unreliable especially for sizes 1.5 inches in diameter and above. Bostec has developed a special class of conformable diamond seals that are directly interchangeable replacements of C-seals and that are 100% reliable. Sizes are available from 1” to 50” in diameter and all are 100% guaranteed.

H-Seals — knife edge seals to replace metal O-rings and C-seals:

Bostec developed and patented its proprietary H-Seal design as an alternative to unreliable metal O-rings and fragile C-seals. H-Seals are a knife edge design and provide the most robust metal seal in existence. When introduced in the early 2000s, H-Seals immediately came into wide adoption across SEMI. Following on the success of H-Seals, Bostec later developed other patent-based variants, and all are now manufactured in-house by Bostec.

Bostec H-Seal UHV Metal Gasket

H-Seals are guaranteed to perform at a leak-rate of 1 x 10-11 standard cubic centimeters/sec (helium) at a pressure of 2.5 x 10-10 torr.

The H-Seal gland must be machined into the flange, thus the typical flat C-seal flange is replaced. H-Seals have a number of advantages over C-seals: H-Seals can be used simultaneously as a UHV and UHP seal capable of withstanding 20,000 psi. H-Seals require significantly less force to seal than C-seals (on the order of half), which allows smaller fasteners, smaller footprints and reduces weight. H-Seals are self-centering and self-limiting, cannot be overtightened, tolerate significant misalignment, and have a self-protecting outer rim that prevents the seal from being damaged in production environments. Bostec manufactures standard H-Seals up to 65 inches in diameter, and larger with special designs.

In addition to being a superior UHV seal, H-Seal’s 20,000 psi delta pressure has led to their adoption in oil-field and deep well applications. H-Seals can be used in both internal and external pressure designs without changing the configuration of the H-Seal itself. In contrast, a C-seal designed configuration cannot be used in both simultaneous scenarios without changing the design from an external to an internal C-seal design. In effect, the cost reduction by using H-Seals is effectively to save half the cost of the H-Seal itself (2 for 1).

Developed in the late 1960’s, C-seals were developed at CERN as an alternative to elastomeric O-rings, and they found their way into many UHV, SEMI and outer space applications. However, they were soon found to be problematic. Unreliability is the biggest drawback with typical first installation yields often under 50% – you have to install two or three to get one to work. Unrealistically tight tolerances, requirement for near perfect sealing surfaces and no real spring-back are root causes of most problems. In addition, bake-out is limited to 100ºC.

What further distinguishes Bostec H-Seals from C-seal design is the “value added” design with respect to tolerancing of the actual mating components. For example, with the NASA DaVinci project the main seals are between 27” mean diameter to 31” mean diameter. C-seals can only accommodate this with a “tolerance” caveat. C-Seals have a tolerance that is 4% of the free-height of the seal. For example, for NASA’s DaVinci purposes, C-Seals from 0.080” free-height, would encompass a lower and upper bound design. The tolerancing parameter, i.e. the 4% free-height, would then make the flatness of the sealing surface (on both parts) 0.003”. Because perfect machined surfaces are not practically possible, the usual method is to split the flatness into 2 categories, a) required flatness and b) tolerance. By dividing equally, the machinists would have to maintain 0.0015” flatness with a 0.002” tolerance range. To achieve this over a mean diameter of 31” requires machining tolerances that are not achievable.

Bostec’s H-Seal tolerance, on the other hand, is on the order of 0.010” per side. In essence, an 0.008” flatness call-out with 0.002” tolerance, which represents a 4x machining advantage over C-seals and therefore achievable from both cost and time constraints.

Submit your designs and specs