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STI/SFPA Industry Page (Steel Tank Institute/Steel Plate Fabricators Association)

The Steel Tank Institute/Steel Plate Fabricators Association is an organization dedicated to promoting the quality of steel tanks and plate fabrication. Through industry collaboration and stringent standards, it ensures the integrity and reliability of steel tanks used in various applications. Organization members benefit from access to cutting-edge research, training, and certification programs.

At Coastal Flange, we offer a comprehensive range of flange products and services tailored to meet our clients’ needs. Our expertise in flange manufacturing and fabrication ensures the highest standards of quality, precision, and reliability in every product we deliver. From custom-designed flanges to standard specifications, we provide solutions engineered to perform in diverse environments.

AWWA C228-19 Stainless Steel Flanges

Coastal Flange manufactures and supplies flanges that comply with different industry standards. Within the STI/SFPA framework, we focus on fabricating flanges according to AWWA C228-19 specifications. This guarantees that our products meet the rigorous requirements of the water storage and distribution sector, ensuring compatibility and reliability in industrial applications.

Here are the different pressure classes or tolerances specified within this particular specification:

Class SA

Class SA flanges are engineered to endure a pressure of 50 pounds per square inch (psi). They are often used in applications where lower pressure requirements suffice, including water supply lines, small-scale irrigation systems, or low-pressure industrial processes. Despite their lower pressure rating, these flanges offer reliable sealing and containment, ensuring the integrity of the pipeline system.

Class SB

Class SB flanges have a pressure rating of 86 psi and provide increased resilience than Class SA. They balance pressure capacity and cost-effectiveness, making them a versatile choice for various water infrastructure projects. These include medium-pressure applications in municipal water distribution systems, wastewater treatment plants, and industrial facilities.

Class SD

Class SD flanges are designed to handle higher pressure levels, ranging from 150 to 175 psi. They offer robust performance and durability, ensuring reliable operation in demanding environments. This makes them well-suited for applications requiring elevated pressure containment, including large-scale water transmission pipelines and industrial processes involving pressurized fluids.

Class SE

With a pressure rating of up to 275 psi, Class SE flanges deliver enhanced strength and durability. They provide reliable performance under high-pressure conditions, contributing to the safety and efficiency of the overall system. These flanges are utilized in infrastructure projects requiring elevated pressure handling capabilities, such as water supply networks serving densely populated areas.

Class SF

Class SF flanges have the highest pressure rating within AWWA C228-19 specifications, withstanding pressures of up to 300 psi. They provide robust and dependable performance in challenging environments, guaranteeing the integrity and reliability of the water infrastructure system. Therefore, they are designed for applications requiring maximum pressure containment, such as long-distance water transmission pipelines.

Flanges Related to STI/SFPA

Each of the following flange types serves specific purposes and offers distinct advantages:

Blind Flanges


60” Blind Flange

Blind flanges are solid disks that block off a pipeline or create a termination point. In STI/SFPA applications, they are often employed for isolation purposes, as maintenance access points, or to cap off unused pipeline sections. They are commonly used in pipelines carrying fluids or gases where temporary or permanent closure is necessary for safety or maintenance.

Weld Neck Flanges

weld-neck- flangesCustom High Pressure Weld Neck Flange

Weld neck flanges are characterized by a long, tapered hub that transitions smoothly into the pipe’s wall thickness. In STI/SFPA contexts, they are preferred for critical applications requiring high strength and leak resistance. These include high-pressure and high-temperature environments where reliability and structural integrity are crucial, such as oil and gas pipelines, petrochemical plants, and refineries.

Slip-On Flanges

Slip-on flanges have a bore slightly larger than the outer diameter of the pipe, allowing the flange to slip over the pipe end. These components are highly valued for their ease of installation and cost-effectiveness in STI/SFPA-related projects. They are commonly employed in low-pressure and non-critical applications requiring quick assembly and disassembly.

Choose Coastal Flange for Unmatched Flange Expertise

At Coastal Flange, we prioritize precision engineering to guarantee that each flange fulfills the highest performance and durability standards. We employ advanced manufacturing techniques and adhere to strict quality control measures throughout production. We also collaborate with industry experts and organizations to stay at the forefront of technological advancements and best practices.

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