Graf Plastics GmbH v. Infiltrator Water Tech LLC

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Graf Plastics GmbH (Germany)
  • Defendant: Infiltrator Water Technologies, LLC (Delaware)
  • Plaintiff’s Counsel: Shaw Keller LLP; Baker & Hostetler LLP (Of Counsel)
• Case Identification: 1:19-cv-00076, D. Del., 01/14/2019
• Venue Allegations: Venue is alleged to be proper in the District of Delaware because the Defendant is a Delaware corporation and therefore resides in the district.
• Core Dispute: Plaintiff alleges that Defendant’s IM Series of two-piece plastic water tanks infringes a patent directed to the structural design of such tanks, which allows for efficient shipping and on-site assembly.
• Technical Context: The technology pertains to large, modular plastic tanks used for applications such as septic systems or rainwater harvesting, where the ability to transport tank components compactly and assemble them reliably on-site is a significant logistical and cost factor.
• Key Procedural History: The complaint alleges that Defendant had knowledge of Plaintiff’s patented product, the GRAF Carat S tank, since at least January 2012, when Defendant’s then-parent company allegedly used a photograph of Plaintiff's product in a promotional publication. Plaintiff’s product has been marked with the patent number since at least mid-2011.

Case Timeline

Date	Event
2006-09-04	'338 Patent Priority Date
2010-12-21	'338 Patent Issue Date
2011-06-30	Plaintiff's GRAF Carat S product on sale and marked with patent number (approx.)
2012-01-17	Defendant's parent co. allegedly publishes photo of Plaintiff's product
2019-01-14	Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 7,854,338 - "Water Tank and Method for Manufacturing a Water Tank," issued December 21, 2010

The Invention Explained

• Problem Addressed: The patent describes a logistical and manufacturing dilemma for large plastic water tanks. Tanks assembled at the factory are bulky and expensive to transport. Tanks shipped in halves for on-site assembly can be difficult and costly to join reliably, and prior art designs for separable tanks were not suitable for creating a permanent, welded version. (’338 Patent, col. 2:1-24).
• The Patented Solution: The invention discloses a design for two identical, injection-molded tank halves with specific "opening edge structures." These structures are designed to be versatile, allowing the same tank halves to be either (1) clamped together with a seal to form a separable tank or (2) welded together to form a permanent, monolithic tank. (’338 Patent, col. 3:23-41). The key is that the fitting surfaces are wide enough to provide a substantial area for welding, a feature the patent claims was lacking in prior separable designs. (’338 Patent, col. 3:54-61).
• Technical Importance: This dual-use design enables a manufacturer to use a single, costly injection mold to produce parts that can satisfy different market demands—those prioritizing low-cost shipping and on-site assembly, and those preferring a pre-assembled, monolithic tank. (’338 Patent, col. 3:48-54).

Key Claims at a Glance

• The complaint asserts independent claim 1 and dependent claims 2, 3, and 4. (Compl. ¶19).
• Independent Claim 1 recites a water tank with essential elements including:
  • Being joined from at least two open identical injection molded tank parts.
  • Having opening edge structures with a flat inner opening edge, a sealing receiving channel, and an outer flat opening edge.
  • The inner and outer fitting surfaces having a width exceeding the thickness of the tank wall and sealing channel wall by at least about one half.
  • The structures being designed such that the water tank is to be assembled in a separable watertight tank version by local releasable clamping.
  • A shape of a hollow cylinder with semi-cylindrical parts and rounded end caps.
  • Parallel ribs in the end caps and semi-cylindrical parts.
  • The ribs tapering inwardly to define a closed, trapezoidal or triangular cross-section at the opening edge.
  • An extension of the inner fitting surface defined by each rib end, which surrounds a recess.
  • An insertion socket for a centering member formed in the recesses.

III. The Accused Instrumentality

Product Identification

• Defendant’s IM Series tanks, including the IM-540, are identified as the Accused Tanks. (Compl. ¶2, ¶20).

Functionality and Market Context

• The Accused Tanks are described as two-piece, injection-molded polypropylene tanks designed for efficient shipping and on-site assembly. (Compl. ¶9, ¶20). The complaint alleges the two open halves can be stacked for transport, as shown in a photograph of six stacked tank parts. (Compl. ¶21-22). The halves are allegedly joined on-site using a series of "noncorrosive plastic alignment dowels and locking seam clips" to form a watertight tank. (Compl. ¶26). The complaint asserts that the Accused Tank is "nearly an identical copy of the Graf tank," Plaintiff's commercial embodiment of the patent. (Compl. ¶12).

IV. Analysis of Infringement Allegations

U.S. Patent No. 7,854,338 Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A water tank made from plastic material, which water tank is to be joined from at least two open identical injection molded or injected molded and embossed tank parts,	The Accused Tanks are constructed from injection molded polypropylene and are joined from two open, identical tank halves. A photograph shows a stack of the open tank halves. (Compl. ¶21).	¶20, ¶22	col. 10:18-20
the tank parts having opening edge structures matching each other in a joining plane... each opening edge structure having a flat inner opening edge continuing a wall of the tank part,	The tank parts have matching opening edge structures, including a flat inner opening edge. A photograph annotates this feature. (Compl. ¶23).	¶23	col. 10:21-24
a sealing receiving channel for a sealing means, the sealing receiving channel being open towards the joining plane,	The opening edge structures include a receiving channel for a seal, identified as an "engineered EPDM gasket." A photograph annotates this channel. (Compl. ¶23-24).	¶23, ¶24	col. 10:24-26
and an outer flat opening edge continuing a wall of the sealing receiving channel,	The opening edge structures include an outer flat opening edge. (Compl. ¶23).	¶23	col. 10:26-28
the opening edges being... inner and outer fitting surfaces... with a width exceeding the thickness of the wall of the tank part and the wall of the sealing receiving channel by at least about one half,	The complaint alleges that the width of the inner and outer fitting surfaces exceeds the wall thickness by at least one half, referencing a photograph comparing the fitting surfaces to the wall thickness. (Compl. ¶25).	¶25	col. 10:30-35
the opening edge structures being designed such that the water tank is to be assembled in a separable watertight tank version by local releasable clamping joining of the opening edge structures,	The Accused Tank is a two-piece design fastened with "plastic alignment dowels and locking seam clips." A photograph shows the assembled tank with orange clips. (Compl. ¶26).	¶26	col. 10:35-39
wherein the water tank at least substantially has a shape of a hollow cylinder consisting of substantially semi-cylindrical tank parts each having outwardly rounded end caps,	The Accused Tank has the shape of a hollow cylinder with rounded end caps. A cutaway drawing and a photograph of a tank half illustrate this geometry. (Compl. ¶27).	¶27	col. 10:39-43
wherein a cylinder axis is situated in the joining plane,	An end-view diagram from Defendant's materials is used to show the cylinder axis is located in the joining plane. (Compl. ¶28).	¶28	col. 10:43-44
ribs in each tank part being arranged parallel to each other in both end caps and in the semi-cylindrical parts with the ribs formed in the end caps terminating with a respective distance from the first and last ribs...,	The Accused Tanks have parallel ribs in the end caps and semi-cylindrical parts. Photographs show the parallel arrangement. (Compl. ¶29).	¶29	col. 10:44-50
and wherein the ribs are tapering inwardly and define at each rib end a closed, substantially trapezoidal or triangular cross-section within the opening edge structure,	The ribs allegedly taper inwardly to define a trapezoidal or triangular cross-section at the opening edge. An annotated photograph shows this alleged shape. (Compl. ¶30, ¶12 fig.).	¶30	col. 10:50-54
wherein an extension of the inner fitting surface defined by each rib end has a shape of a closed strip... having substantially constant width, the edge strip surrounding a recess which is set back...	The rib ends allegedly define a closed strip of constant width surrounding a recess. An annotated photograph illustrates these alleged features. (Compl. ¶30-31).	¶30, ¶31	col. 10:54-60
and wherein an insertion socket for inserting a centering member is formed in the recesses of the rib ends of at least some of the ribs.	The rib ends allegedly have insertion sockets for "plastic alignment dowels," which act as centering members. Photographs show the sockets and a dowel. (Compl. ¶32-33).	¶32, ¶33	col. 10:60-64

Identified Points of Contention

• Scope Questions: The patent's abstract and summary emphasize that the invented tank parts can be used selectively to create either a separable version (with clamps) or a monolithic version (by welding). (’338 Patent, Abstract; col. 3:31-37). The claim language, however, only recites that the structure is "designed such that the water tank is to be assembled in a separable... version." This raises the question of whether a product that is only ever assembled separably, as alleged for the Accused Tanks, falls within the scope of the claim if its structure is not also suitable for the monolithic welding described as a key aspect of the invention.
• Technical Questions: The complaint alleges the accused tank parts are "identical," a prerequisite of claim 1. (Compl. ¶22). The factual basis for this conclusion will be subject to discovery and expert analysis. Additionally, the claim requires the width of the fitting surfaces to exceed the wall thickness by "at least about one half." (Compl. ¶25). The complaint makes this allegation with photographic support, but a quantitative analysis will be required to confirm infringement of this limitation.

V. Key Claim Terms for Construction

The Term: "identical"

• Context and Importance: This term is critical because if the two halves of the accused tank are not "identical," a primary limitation of claim 1 is not met. Practitioners may focus on this term because the patent emphasizes that producing identical parts from a single mold is a key manufacturing advantage. (’338 Patent, col. 7:20-24).
• Intrinsic Evidence for a Broader Interpretation: A party might argue for the term's plain and ordinary meaning, which could accommodate minor, non-functional variations that arise during manufacturing, as the patent does not provide a specific definition that excludes such tolerances.
• Intrinsic Evidence for a Narrower Interpretation: The specification repeatedly states that the "tank parts 1 are identical" and "may be produced in one and the same injection mould." (’338 Patent, col. 7:15-24). This language may support an interpretation requiring the parts to be structurally interchangeable and without any designed differences.

The Term: "opening edge structures being designed such that the water tank is to be assembled in a separable watertight tank version"

• Context and Importance: The construction of this phrase will be central to the scope of the claim. The dispute may turn on whether "designed such that" merely requires that the structure is capable of separable assembly, or if it implies a broader set of characteristics tied to the invention's dual-purpose nature as described in the specification.
• Intrinsic Evidence for a Broader Interpretation: The plain language of the claim focuses only on the suitability for separable assembly. An argument could be made that if the structure meets all the requirements for being joined by clamping, as alleged in the complaint (Compl. ¶26), this limitation is satisfied, regardless of its suitability for other assembly methods.
• Intrinsic Evidence for a Narrower Interpretation: The specification states that each tank part "selectively may be used for manufacturing either a monolithic water tank which is welded... or for assembling a conventionally clamped and sealed water tank." (’338 Patent, col. 3:31-37). A party could argue that, read in this context, a structure is only "designed such that" it can be assembled separably if it also embodies the features, such as wide welding surfaces, that enable the selective alternative of monolithic assembly, which is the stated point of novelty.

VI. Other Allegations

• Indirect Infringement: The complaint does not include a formal count for indirect infringement, focusing its infringement claim on direct infringement by Defendant. (Compl. ¶47). However, it does allege that Defendant "knows and has known" of infringement by its "distributors and/or its customers," which may provide a factual basis for a future indirect infringement theory. (Compl. ¶12).
• Willful Infringement: The complaint alleges willful infringement. (Compl. ¶13). This allegation is based on purported pre-suit knowledge of the ’338 Patent dating back to at least January 2012, when Defendant’s then-parent company allegedly used a photograph of Plaintiff's patented product in a publication. (Compl. ¶11). The allegation is further supported by the assertion that the Accused Tank is a "nearly an identical copy" of Plaintiff's commercial product. (Compl. ¶12).

VII. Analyst’s Conclusion: Key Questions for the Case

• A core issue will be one of claim scope: can the phrase "designed such that the water tank is to be assembled in a separable... version" be met by a product that is only suitable for separable assembly, or must the claim, when read in light of the specification, be construed to require a structure that is also suitable for the monolithic welding that the patent presents as a key inventive concept?
• A key evidentiary question will be one of structural identity and measurement: can Plaintiff prove through factual evidence that the two halves of the Accused Tank are structurally "identical" and that their fitting surfaces meet the specific dimensional requirement of exceeding the wall thickness by "at least about one half" as recited in the claim?