AWWA D103 vs D108: Bolted Tank And Aluminum Dome Roof Standards
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AWWA D103 vs D108: Bolted Tank And Aluminum Dome Roof Standards
AWWA D103 and AWWA D108 are two distinct AWWA standards that together define a complete bolted storage-tank system: D103 governs the field-erected bolted carbon-steel tank shell, bottom, roof and connections, while D108 governs the aluminum geodesic dome roof that sits on top of it. They are complementary, not competing — a single project often calls out D103 for the tank and D108 for the dome. Specifiers who treat them as one standard risk either an under-specified shell or an over-specified, mis-scoped roof. Knowing which standard owns which scope lets an owner write a clean specification and verify the supplier's deliverables against the right document.
A bolted steel water tank and its roof are engineered as one structure, but the American Water Works Association writes the rules for each in separate standards. AWWA D103 covers the bolted tank itself; AWWA D108 covers the aluminum dome that often caps it. When both are present on a data-center, industrial or municipal water project, the documents must call out the correct standard for each scope. Confusing the two produces gaps in responsibility, coating acceptance and structural verification. This article sets out what each standard governs, where their scopes meet, and how to specify them on a single project.
D103 Owns The Bolted Tank Shell, Bottom And Connections
AWWA D103 is the standard that governs field-erected bolted carbon-steel tanks for water storage, covering the shell, bottom, roof, connections and the bolting that holds them together. It is the bolted-tank counterpart to the welded-tank rules and is the document most North American owners reference when they specify a bolted ground storage tank.
· Shell design. D103 sets the allowable stresses, minimum plate thicknesses, and the stepped course schedule that the hydrostatic head demands as depth increases.
· Bolting and joints. The standard defines the bolt grades, gasket type and joint detailing that keep the shell watertight under hydrostatic and wind load.
· Bottom and foundation interface. The tank bottom, its bearing and the transition to the foundation are within D103 scope, with loads passed to a foundation designed to local geotechnical and seismic code.
· Coating and lining. D103 addresses protective coatings and linings for the wetted surface, with acceptance referenced to potable-contact standards such as NSF/ANSI 61 where the water is drinkable.
For a bolted tank, D103 is the core construction standard; everything else (seismic input, execution certification, lining acceptance) wraps around it.
D108 Owns The Aluminum Geodesic Dome Roof
AWWA D108 is the standard that governs factory-fabricated aluminum geodesic dome roofs placed on circular tank openings, and it is silent on the tank shell beneath it. The dome is a self-supporting clear-span structure of triangular aluminum panels, and D108 is the document that defines how that roof is designed and supplied.
Scope item | AWWA D103 (tank) | AWWA D108 (dome) |
Structure covered | Bolted carbon-steel tank shell, bottom, roof | Aluminum geodesic dome roof only |
Material | Carbon steel, bolted | Aluminum, bolted panels |
Load path | Hydrostatic, wind, seismic to foundation | Snow, wind, self-weight to tank rim |
Coating | Steel coating/lining acceptance | Aluminum, typically uncoated/corrosion-resistant |
Interface | Provides the rim and anchorage | Sits on and anchors to the D103 rim |
Because the dome and the tank are different materials with different failure modes, AWWA deliberately separates them. A supplier may be qualified to D103 for the tank but must also show D108 compliance for the dome, or source the dome from a specialist.
How The Two Standards Pair On One Project
A complete bolted-tank-with-dome project is specified by calling out D103 for the tank and D108 for the roof, with the rim interface defined so neither standard leaves a gap. The two documents meet at the tank top rim, where the dome's attachment and load transfer are defined.
1. Single specification, two scopes. The owner's specification names D103 for the tank and D108 for the dome, and identifies who supplies and warrants each.
2. Rim and anchorage. The D103 tank provides the top course and rim; the D108 dome anchors to it with matched geometry and bolt pattern.
3. Combined load cases. Wind and snow on the dome transfer to the tank shell and then to the foundation; the D103 shell check includes the dome's reactions.
4. Seismic interaction. Where the local seismic basis is ASCE 7, both the tank (D103) and the dome (D108) inertia loads are carried into the same foundation design.
The practical rule: the standards pair by design, and the supplier's drawings show both the D103 tank and the D108 dome with the connecting interface on one coordinated set.
What Each Standard Does Not Cover
Neither D103 nor D108 is a complete project code on its own, and the gaps they leave must be closed by other standards and local codes. Understanding the exclusions prevents a false sense of full coverage.
Standard | Explicitly does not cover |
AWWA D103 | Seismic input spectrum (uses ASCE 7 / local code), European execution certification (EN 1090), potable-contact lining acceptance (NSF/ANSI 61, WRAS) |
AWWA D108 | The tank shell, bottom and foundation, and the structural behavior of the vessel the dome rests on |
Other documents fill the holes: ASCE 7 or EN 1991/EN 1998 supply the seismic and wind basis, EN 1090 governs CE-marked execution in Europe, and NSF/ANSI 61 or WRAS confirm potable-contact suitability of the lining. A project that satisfies D103 and D108 but ignores these wraparound standards is not fully specified.
Material And Coating Selection At The Interface
The tank-to-dome interface is where steel and aluminum meet, and the specification must address the dissimilar-metal detail so corrosion and galvanic action are controlled. The bolted steel tank is coated per D103; the aluminum dome is inherently corrosion resistant. At the connection, the supplier should detail isolation or compatible fasteners.
· Galvanic separation. Where steel and aluminum fasten together, appropriate washers, coatings or dielectric isolation prevent galvanic corrosion at the rim.
· Coating continuity. The D103 top course and rim coating must be complete to the dome attachment line; the dome supplier's edge detail should not break that barrier.
· Access and ventilation. D108 domes often include walkways, hatches and vents; these must line up with the D103 tank's roof penetrations and overflow/vent requirements.
Getting the interface detail right is what turns two separately-compliant standards into one watertight, durable structure.
Standard Conformance And Company Capability
This article is a standards guide rather than a project citation; no fabricated case is presented. Center Enamel designs and fabricates bolted carbon-steel tanks referenced to AWWA D103-09, and supplies aluminum geodesic dome roofs referenced to AWWA D108, with the rim interface coordinated on a single drawing set. Where a project requires European execution certification, the structure is referenced to EN 1090 for CE marking, and potable-contact linings carry NSF/ANSI 61 and WRAS acceptance. The company's GFS bolted tanks are also designed to ISO 28765, giving a vitreous-enamel alternative to the bare carbon-steel shell D103 addresses. Center Enamel (Shijiazhuang Zhengzhong Technology Co., Ltd) has produced bolted tanks since 2008, holds close to 200 enamel-related patents, completes more than 30,000 installed projects, and supplies single tanks up to 60,000 m³ under ISO 9001 and ISO 45001 manufacture.
Center Enamel Engineering Capability
Center Enamel (Shijiazhuang Zhengzhong Technology Co., Ltd) has designed and fabricated bolted storage tanks since 2008. As the first glass-fused-to-steel (GFS) tank manufacturer in China, the company holds close to 200 enamel-related patents, produces roughly 300,000 enamel-coated steel plates a year, has completed more than 30,000 installed projects and supplies its tanks to over 100 countries. The new 150,000 m² production base was added to raise output capacity, and single tanks are supplied up to 60,000 m³. Manufacturing runs under ISO 9001 and ISO 45001, with product certification including NSF/ANSI 61, WRAS, FDA, LFGB, CE (EN 1090), ISO 28765, FM, BSCI and EUROCODE, and design referenced to AWWA D103-09, AWWA D108, EN 1090 and ISO 28765 where the application requires it.
Frequently Asked Questions
Q1: Are AWWA D103 and D108 the same standard?
A1: No. D103 governs the bolted carbon-steel tank (shell, bottom, roof, bolting, lining); D108 governs only the aluminum geodesic dome roof. They are complementary and usually specified together on a domed-tank project.
Q2: Does AWWA D108 cover the tank shell?
A2: No. D108 is limited to the aluminum dome roof and its attachment to the tank rim. The shell, bottom and foundation remain within D103 (or another tank standard).
Q3: Can a bolted tank be supplied without a D108 dome?
A3: Yes. D103 covers the tank with its own roof options; the D108 aluminum dome is specified when a clear-span, low-maintenance, corrosion-resistant roof is wanted on top of a D103 tank.
Q4: Who is responsible for the tank-to-dome interface?
A4: The interface belongs to whoever coordinates the two standards — typically the tank supplier, who must show the D103 rim and the D108 anchorage matched on one drawing set so neither standard leaves a gap.
Q5: Does D103 include seismic design?
A5: D103 requires the tank to be checked for seismic and wind load, but the seismic input spectrum comes from the local code (ASCE 7 in the Americas; EN 1991/EN 1998 in Europe). A compliant project performs both.
Q6: What about potable-water contact on a D103 tank?
A6: D103 addresses the protective coating/lining, but potable contact also needs acceptance such as NSF/ANSI 61 or WRAS, which wrap around the D103 construction standard.
Q7: Is an aluminum dome heavier or lighter than a steel roof?
A7: Aluminum geodesic domes are lightweight and self-supporting with no internal columns, which reduces the roof load transferred to the D103 shell and simplifies the foundation — a key reason owners choose D108 over a conventional steel roof.
AWWA D103 and AWWA D108 are two separate but paired standards: D103 owns the bolted carbon-steel tank, and D108 owns the aluminum dome that caps it. They meet at the tank rim, and a clean specification calls out each for its own scope while coordinating the interface on one drawing set. Neither is a full project code — seismic, execution and potable-contact requirements wrap around them through ASCE 7, EN 1090 and NSF/ANSI 61 or WRAS. Specify both correctly and the result is a fully covered, durable bolted-tank-and-dome system.
Talk to an Engineer
For a bolted tank with an aluminum dome, send us the capacity and diameter, the stored liquid and whether it is potable, the site wind and seismic data, and the required standards (AWWA D103, AWWA D108, EN 1090, NSF/ANSI 61/WRAS). We will return a coordinated tank-and-dome specification with the D103 shell and D108 rim interface detailed, coating and lining acceptance documented, and the seismic and foundation checks performed to the applicable ASCE 7 or EN 1998 basis.
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