How Custom FRP and Dual-Laminate Tanks Are Manufactured

Custom FRP and dual-laminate tanks are not built from one standard recipe. The manufacturing process starts with the service conditions and project design basis, then controls the corrosion layer, structural laminate, fittings, cure and required inspections around that specific duty.

Looking for a custom tank? Review Troy Dualam’s custom FRP and dual-laminate tank capabilities, compare industrial water-tank materials, or send the service conditions to our team.

Stage 1: Define the Service and Design Basis

The project begins by defining what the tank will contain, chemical concentration, operating and upset temperature, specific gravity, pressure or vacuum, dimensions, nozzles and supports, wind and seismic loads, installation conditions, and applicable owner or code requirements. Calculations and drawings are then developed to the identified design basis.

Troy Dualam Inc. holds an active ASME RTP Certificate of Authorization for shop fabrication within its approved scope. Depending on the project, the specified design basis may be ASME RTP-1, ASTM D3299 or another identified standard; no tank is automatically certified or governed by all of them. ASTM D4097 is a legacy standard that was withdrawn in 2026 after its contact-moulded tank requirements were incorporated into ASTM D3299.

Stage 2: Select the Corrosion-Resistant System

For conventional FRP construction, the corrosion barrier is selected for the intended service. The resin system, veil and corrosion-layer details are project-specific. The structural laminate behind that barrier is designed separately to carry the required loads.

For dual-laminate construction, a selected thermoplastic corrosion liner is backed by structural FRP. Liner material, joining method, surface preparation and inspection requirements depend on the complete service and specified system. Dual laminate is evaluated when that additional thermoplastic barrier is technically justified; it is not automatically the better choice for every tank.

Stage 3: Prepare the Tooling or Thermoplastic Liner

For conventional FRP, the mould or mandrel is prepared for the specified fabrication method and surface requirements before the corrosion barrier is applied. For dual laminate, the thermoplastic liner components are formed and joined according to the approved liner system before structural over-lamination begins.

Stage 4: Build the Structural Laminate

The load-carrying laminate may be fabricated by hand lay-up, filament winding or a project-specific combination of methods. Reinforcement orientation, laminate thickness and resin system follow the approved design and service conditions rather than a generic layer count. Cylindrical shells, heads, transitions and local reinforcements may therefore use different laminate details.

Stage 5: Control Cure and Fabrication

Resin mixing, application, cure and production controls follow the approved fabrication procedure. Fabricators monitor and record the controls required by the design basis and quality plan. Cure is not assumed from a fixed number of hours, and pressure is not automatically part of every process.

Stage 6: Add Nozzles, Manways, Supports and Internals

Nozzles, manways, supports, lifting and anchoring details, baffles, dip pipes and other internals are added and reinforced according to the approved design. Their geometry and local laminate details must account for the loads transferred into the tank shell.

Stage 7: Complete the Required Inspection and Testing

Quality records and inspections are project-specific. Visual inspection and documented checks or tests follow the specified design basis and approved quality plan. Depending on the equipment and project requirements, these activities may include laminate-thickness checks, Barcol hardness, acetone sensitivity, leak or hydrostatic testing, and holiday or spark testing of an applicable thermoplastic liner. They are not represented as tests performed on every vessel.

Potable-Water Tanks Require Project-Specific Verification

Troy Dualam can fabricate custom FRP tanks for potable-water storage. The resin, corrosion barrier, internal surface, fittings, cleaning or disinfection method and jurisdictional or owner requirements must be confirmed for the project. Potable-water capability does not imply that every material system or completed tank carries a blanket NSF/ANSI 61 listing.

Frequently Asked Questions

How are custom FRP tanks manufactured?

The process defines the service and design basis, selects the corrosion-resistant system, prepares the tooling or liner, builds and cures the structural laminate, installs fittings and supports, and completes the required project-specific inspections and tests.

What is the difference between hand lay-up and filament winding?

Hand lay-up places reinforcement and resin manually and is useful for complex shapes and local details. Filament winding places continuous reinforcement around suitable geometry in controlled orientations. A custom tank may use either method or a combination according to the approved design.

Is every Troy Dualam tank ASME RTP-1 certified?

No. Troy Dualam holds an active ASME RTP Certificate of Authorization for shop fabrication within its approved scope, but certification and the governing design basis are determined for the individual project.

How are FRP tanks tested?

The required inspections and tests depend on the design basis, equipment type and project quality plan. No single test list applies automatically to every FRP or dual-laminate tank.

Planning a custom tank or vessel? Contact Troy Dualam with the stored fluid, concentration, temperature, specific gravity, pressure or vacuum, dimensions, installation conditions and applicable project requirements.