Adhering to the AWWA D-100 standard, our tanks are constructed with ASTM A36 carbon steel as the primary material, while other approved materials are used to construct external components. Ensuring the safety, integrity and function of your finished tank is our highest priority. That’s why we support in-house, custom fabrication and hire certified welders with intimate knowledge of AWWA D-100 Section 10, which provides specific instructions for tank erection. With over a century in tank design & field erection, we’ve continually developed and critiqued our design and construction process. Some design specifics considered include:
Roof Types Selection
Summary
Column / Structurally Supported Cone Roof
A common fixed-roof design for tanks with relatively low pressure. They contain a shallow cone roof utilizing a center column of pipe or structural steel. Intermediate columns are commonly used on larger diameter tanks. Internal framing is used to support the roof plates; this may include supporting rafters, clips, tie bars and girders.
Highlights
- Permits for a large diameter roof design
- Rigid structure can be designed for large snow loads
Summary
Column / Structurally Supported Cone Roof
A common fixed-roof design for tanks with relatively low pressure. They contain a shallow cone roof utilizing a center column of pipe or structural steel. Intermediate columns are commonly used on larger diameter tanks. Internal framing is used to support the roof plates; this may include supporting rafters, clips, tie bars and girders.
Highlights
- Permits for a large diameter roof design
- Rigid structure can be designed for large snow loads
- With an API 650 design, the tank can be re-purposed to store many additional liquids
Externally Stiffened
Summary
Self-Supporting Cone
Suitable for small diameter tanks. Roof is supported at the shell.
Highlights
- Roof can be sealed
Summary
Self-Supporting Cone (Externally Stiffened)
Suitable for medium size diameter tanks. The external stiffening can allow additional support for platforms and structures on the roof.
Highlights
- Suitable for tanks with internal roof coating
- External Stiffening allows for a medium sized roof diameter
- Roof can be sealed
Externally Stiffened
Summary
Self-Supporting Cone
Suitable for small diameter tanks. Roof is supported at the shell.
Highlights
- Roof can be sealed
- With an API 650 design, the tank can be re-purposed to store many additional liquids
Summary
Self-Supporting Cone (Externally Stiffened)
Suitable for medium size diameter tanks. The external stiffening can allow additional support for platforms and structures on the roof.
Highlights
- Suitable for tanks with internal roof coating
- External Stiffening allows for a medium sized roof diameter
- Roof can be sealed
- With an API 650 design, the tank can be re-purposed to store many additional liquids
Externally Stiffened
Summary
Self-Supporting Umbrella
The umbrella roof consists of a modified dome, where the horizontal section is a regular polygon with multiple sides with roof plates, supported only at the periphery. Dome roofs are also possible at a higher cost.
Highlights
- Can often be built from thinner material than a cone
- The bulk of the roof work can take place at grade
Summary
Self-Supporting Umbrella (Externally Stiffened)
The umbrella roof consists of a modified dome, where the horizontal section is a regular polygon with multiple sides with roof plates, supported only at the periphery. The roof is stiffened with structural beams, welded to the exterior of the umbrella sections as per design. Dome roofs are also possible at a higher cost.
Highlights
- Can often be built from thinner material than a cone
- The bulk of the roof work can take place at grade
- External stiffening allows for a medium sized tank diameter
Externally Stiffened
Summary
Self-Supporting Umbrella
The umbrella roof consists of a modified dome, where the horizontal section is a regular polygon with multiple sides with roof plates, supported only at the periphery. Dome roofs are also possible at a higher cost.
Highlights
- Can often be built from thinner material than a cone
- The bulk of the roof work can take place at grade
- With an API 650 design, the tank can be re-purposed to store many additional liquids
Summary
Self-Supporting Umbrella (Externally Stiffened)
The umbrella roof consists of a modified dome, where the horizontal section is a regular polygon with multiple sides with roof plates, supported only at the periphery. The roof is stiffened with structural beams, welded to the exterior of the umbrella sections as per design. Dome roofs are also possible at a higher cost.
Highlights
- Can often be built from thinner material than a cone
- The bulk of the roof work can take place at grade
- External stiffening allows for a medium sized tank diameter
- With an API 650 design, the tank can be re-purposed to store many additional liquids
Design Specifics
Considerations
- Allowable external loads on tank shell openings
- Environmental loads (wind, seismic, snow, importance factors)
- Foundation design
Requirements
- Maximum capacity
Materials of Construction
- Carbon steel, stainless steel or duplex steel
Corrosion Protection
- Linings, coatings
- Cathodic protection
Access Systems
- Radial or spiral stairways
- Roof access systems
Heat Conservation
- Various insulation products
Standards
TIW designs tanks to both AWWA D-100 and API standards, each having its benefits based on the storage application. We have the capability to design your AWWA D-100 welded steel tank in various sizes and capacities. TIW tanks are large vertical and cylindrical structures requiring field erection. Aboveground, flat bottom, ground supported, welded steel in various sizes and capacities for internal pressures not to exceed specific atmospheric temperatures.
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AWWA D-100 Standard
Requirement
The American Water Works Association has set these guidelines for the construction of welded carbon steel tanks for water storage. The American National Standards Institute has adopted them as best practices within the industry for designing and building tanks to be used in water systems where the internal pressure does not exceed atmospheric pressure.
Typical Usage
- Potable Water Storage
- Firewater Storage
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API 650 Standard
Requirement
The American Petroleum Industry (API) has established the 650 standard, setting minimum requirements for the design, material, construction, and testing of aboveground, open and closed-top, cylindrical welded steel storage tanks of various capacities and sizes.
They are designed as non-refrigerated tanks with a minimum material thickness of 3/16 inch of carbon steel, austenitic duplex stainless steel, and aluminium. Supporting an internal pressure of 2 ½ PSI or less and an operating temperature of -40°F to 500°F. They are commonly used to store products such as crude oil, petroleum by-products, chemicals and process water.
Typical Usage
- Crude Oil
- Refined Gases
- Biofuels
- Process Water
- Sulfur
- Chemicals
Repairs, Modifications & Testing
The API 650 Standard provides details for the minimum testing to be performed to ensure quality workmanship of the tank along with a separate standard, API 653, dedicated to providing a complete set of procedures and tests, specifically for the repair of API 650 tanks.
We are well-known for our expertise in performing repairs and modifications for a wide range of customers. Please see our API 653 Repair Services for more details.
Goto API 650 Product Page: api-650-tanks-various-configurations
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API 620 Standard
Requirements
The API 620 Standard governs the design and construction of large, welded, low-pressure storage tanks. These tanks require an elevated, flat or cone bottom, and a minimum material thickness of 3/16 of an inch in carbon steel, austenitic stainless steel and nickel alloys (low temperature only). These tanks operate as low as -325°F to 250°F with an operating pressure of up to 15 PSI. They are generally utilized for cryogenic liquefies such as LOX, LIN or LNG as well as other chemicals which require internal design pressures exceeding those allowed by 650 tanks.
Typical Usage
- Liquid Oxygen (LOX)
- Liquid Argon (LAR)
- Liquid Nitrogen (LIN)
- Liquified Natural Gas (LNG)
- Natural Gas Liquids (NGL)
- Liquified Propane (LPG)
- Compressed Natural Gas (CNG)
- Anhydrous Ammonia (AA)
- Acidic Chemicals
Appurtenances
Our design engineers can customize a wide ranges of appurtenances on the interior and exterior of your water tank. With our in-house, 200,000 sq ft material processing plant, we look after the fabrication of everything from nozzles, vents and piping to custom stairways, platforms and ladders.
Here are some typical components we design, fabricate and install on our AWWA D-100 tanks…
Internal Components
- Internal Ladders with Fall Arrest Systems
- Piping Subsystems for Multi-Level Sampling
- Overflow
- Pumping
External Attachments
- Nozzles (with flanges, elbows, couplings and more)
- Ladders and Safety Railings
- Stairways: Spiral and Radial:
- Single and Double Stringer Designs with Handrail Variations
- Roof Walkways, Platforms, Joining Catwalks and 360 Degree Handrails
- Shell Manways
- One Roof Access and Two Shell Access Manways
- Rectangular and Circular Hatches
- Insulation Rings
- Rescue Davits
- Shell Vents
- Piping Supports and Grounding Lugs
Managed Services
Protective Coatings & Insulation
TIW offers a wide variety of protective coatings for corrosion prevention including external coating and full internal lining. We also offer alternate corrosion options such as hot dip galvanizing, coating over galvanized components.
Shop Pre-Coating
TIW can shop coat floor plates, shell plates and appurtenances prior to shipping to site. This can help offset the high prices of field coating and help minimize open-air blasting which can be environmentally prohibited in some project locations.
Galvanizing
We provide galvanizing of various tank components – from nozzles, piping and support clips to handrails and platforms. In some cases, both galvanizing and coating are applied providing a superior protection.
Exterior Coatings
These coatings are applied to the exterior of the tank for corrosion protection and cosmetic appearance. Exterior surfaces are typically sand blasted to an SSPC-SP6 finish in preparation for coatings such as:
- High-performance epoxy primers and finish coatings
- Inorganic zinc coatings
- Holding primers
- Acrylic polyurethane coatings
- High-temperature coatings
Interior Linings
When storing potable water, the interior surfaces of the tank are typically prepared with a minimum SSPC-SP10 near white metal blast and completely lined with an epoxy coating or appropriate NSF approved coating. TIW removes all sharp edges prior to sandblasting, and can perform complete Holiday testing (to test for voids in the liner), prior to signing off on the lining. Some typical linings may include:
- Epoxy primers
- Epoxy finish coatings
- Holding primers
- Temperature rated coatings
Insulation
When temperature control is required per design, TIW can supply and install a variety of mechanical insulation to meet the customer’s requirements. Insulation options can vary from the more common insulation batts with external cladding to prefabricated insulated panels. There are also different insulation and cladding material options.
Depending on design and temperature requirements, TIW can offer several insulation materials such as:
- Fiberglass
- Calcium silicate
- Mineral wool
- Cellular glass
- Perlite
- Polyisocyanurate
- Thin blanket
- Aerogel