Ohio Court Construes Coke Oven Corbel Patent: No Adjacency for 'Above,' Third Passageway Not Indefinite.

The case

Vanocur Refractories, LLC filed Vanocur Refractories, LLC v. Fosbel, Inc. on September 8, 2023 in the Western District of New York, and the case was transferred to the Northern District of Ohio on November 6, 2023 after the parties stipulated to the transfer. Vanocur later added Ceramic Holdings Inc. as a defendant by an amended complaint filed October 28, 2024. In an August 25, 2025 order, the court denied in part and granted in part Fosbel's motion to dismiss the amended complaint. The order describes two of the patent's nineteen claims as at issue, claim 1 and claim 10. It dismissed Count One, which relies on the component export provisions of 35 U.S.C. 271(f)(1) and (2), only as to method claim 10, citing Cardiac Pacemakers, Inc. v. St. Jude Medical, Inc., 576 F.3d 1348 (Fed. Cir. 2009), for the rule that section 271(f) does not apply to method patents. Count One remains as to claim 1, and Count Two, for direct infringement under 35 U.S.C. 271(a), survived.

The October 20 order is ECF No. 85. Vanocur and Fosbel briefed claim construction and agreed to forgo a hearing. Ceramic Holdings, joined after briefing closed, filed no claim construction arguments, so the court decided the disputes on the Vanocur and Fosbel briefs and treated claim 1 as representative.

What the patent covers

U.S. Patent 8,266,853, titled "Corbel repairs of coke ovens," concerns the corbel, the structure that sits between a coke oven and its regenerator. As the opinion describes the patent, a corbel uses a network of passageways to route gas, fresh air, and exhaust to the right places without letting them mix, and corbels were traditionally built from hundreds or thousands of silica bricks. The patent proposes building corbels from larger cast blocks to cut construction time and the number of joints where gas or air can leak.

Claim 1 covers a corbel with four parts: a first tier of blocks, each with a horizontal aperture running from front to back and a vertical aperture through its top surface into that horizontal aperture, arranged so the horizontal apertures line up into a first, horizontal passageway; a second tier of blocks placed above the first tier, each with a vertical aperture from top to bottom aligned with the first blocks' vertical apertures to form a second passageway; a third passageway running diagonally from the top of one of the second blocks to a side of at least one of the first and second blocks; and a gas source that provides gas to the first passageway. Claim 10 covers a method of building that corbel by laying the first tier, laying the second tier above it, and introducing gas into the first aperture with the gas source so that the gas passes from the first passageway into the second.

"Above"

Vanocur asked the court to construe "above" as "directly above." Fosbel proposed "in a higher, but not necessarily directly adjacent, place." The court rejected Vanocur's construction and agreed with Fosbel that "above" does not require adjacency, but it declined to adopt Fosbel's wording and held that "above" carries its plain and ordinary meaning. Its main reason was claim 7, which depends from claim 1 and places both the first tier and the second tier above a foundation block. Because claim 1 also places the second tier above the first tier, the second tier cannot be adjacent to the foundation block, so "above" cannot mean "directly above."

The court rejected Vanocur's reliance on drawings that show each tier resting directly on the one below, calling that an attempt to import a limitation from preferred embodiments. It held that a single use of "directly above" in the specification, at column 6, lines 62 to 63, is not an express definition, and that the patent does not use "above" consistently enough to create an implied one. It declined Fosbel's wording because it only restates an easily understood word. The court also overruled Vanocur's objection that Fosbel's expert was not qualified to testify as a person of ordinary skill, and said it expressed no opinion on the separate term "align," which no party asked it to construe.

"Gas source"

Vanocur proposed plain and ordinary meaning, and Fosbel proposed "point of origin from which gas is obtained." The court rejected Fosbel's wording as a longer synonym that adds nothing and held that no construction is needed, but because the parties disputed what structures the term covers, it resolved that dispute. Both sides agreed, and the court held, that a gas source need not be any particular kind of device. The court found Vanocur's view, that the gas source could include the adjacent first blocks through which gas flows, too broad, and agreed with Fosbel that the gas source must be a different structure from a first block. The court reasoned that the first blocks form the first passageway and are a conduit for gas rather than a source of it, that claim 1 says the gas source provides gas to that passageway, and that the gas source and the first blocks are listed as separate limitations, citing Magnolia Medical Technologies, Inc. v. Kurin, Inc., 169 F.4th 1094, 1102 (Fed. Cir. 2026). In a footnote, the court read claim 1 to call for a single gas source for the corbel as a whole.

"Third passageway"

Fosbel argued that the limitation "a third passageway extending diagonally from the top of the one of the second blocks to a side of at least one of the first and second blocks" is indefinite under the pre-AIA version of 35 U.S.C. 112, second paragraph. The court held that none of Fosbel's four arguments met the clear and convincing evidence standard, alone or together. Vanocur proposed plain and ordinary meaning, and Fosbel offered no alternative construction. The court held the limitation not indefinite and gave it its plain and ordinary meaning. It read "at least one of the first and second blocks" disjunctively, citing Kaufman v. Microsoft Corp., 34 F.4th 1360, 1373 (Fed. Cir. 2022). It held that "to a side of" means extending into the space beside a block, not through the block's side, because claim 1 uses "through" when it means through a block, and because the patent's figures show a diagonal passageway formed by notched lateral blocks beside the first blocks.

Fosbel said that figure showed claim 4's air passageway, a different structure. The court agreed the figure shows claim 4's air passageway but noted that both parties' experts agree the third passageway carries air, so claim 4 simply narrows claim 1. The absence of a distance limit for "side" is breadth, not indefiniteness, under Niazi Licensing Corp. v. St. Jude Medical S.C., Inc., 30 F.4th 1339 (Fed. Cir. 2022). The court called the argument that "top" is unclear "specious," and held that the claim need not trace the passageway's full path because its starting point and orientation define its scope.

Practice pointers

A dependent claim that places two separately recited structures "above" a third one can defeat an argument that "above" means "directly above." Drawings that all show one arrangement are preferred embodiments, not lexicography, and a single "directly above" in the specification does not define the claim word. When a court declines to construe a term but the parties dispute its scope, it may still resolve the dispute, as the court did by holding that the gas source must be separate from the first blocks.

What to watch next

The order states that the case will now proceed under the Northern District of Ohio Local Patent Rules. Watch for the post-construction schedule and for any motion practice on claim 1 under sections 271(a) and 271(f) and on claim 10 under section 271(a).