--- title: "Raised Face vs. Flat Face Stainless Steel Flanges: Which Seal Is Better?" date: 2025-07-31T12:30:25Z modified: 2025-08-04T02:02:56Z permalink: "https://www.longanflange.com/blog/raised-face-vs-flat-face-ss-flange/" type: post status: publish excerpt: "" wpid: 3036 categories: - Blog featured_image: "https://www.longanflange.com/wp-content/uploads/2025/06/industrial-flanges-3.webp" featured_image_alt: industrial flanges 3 timestamp: 2025-08-04T02:02:56Z tags: - Blog --- ![](https://lh7-rt.googleusercontent.com/docsz/AD_4nXf5T5ZHa8vecr75absoSiLsFnMmcSLYCKjq8hLoTEcEGUxHtnoDNCUIIQwdqBXdvcGBwpNuEp_ReKVaxjv220HXrArIni7ZA6lSF3FySEKjYpTuwnz6jecGIfzRpPNDp310wRTe9Q?key=hXvFSRqiJsI2xIzt2Q2hTQ) Alt-text: “Stainless steel flanged pipe connections in an industrial setup Don’t know which to choose between raised face flange vs flat face for your stainless steel flange project? Let’s break it down clearly. As a professional stainless steel flange manufacturer, Long’an Flange understands that choosing the right face type impacts long-term reliability. We guide you through the key sealing differences to ensure you get the best performance for your system. ## **What’s the Difference Between RF and FF SS Flanges?** The [main difference](https://www.longanflange.com/wp-content/uploads/wp-mfa-exports/post/raised-face-vs-flat-face-flange.md) between raised face and flat face flanges comes down to how they seal and where they’re used. Each has its place depending on pressure, material, and installation needs. ### Raised Face (RF) An [RF flange](https://www.longanflange.com/wp-content/uploads/wp-mfa-exports/post/raised-face-flange-in-pressure-vessel.md) has a slightly elevated sealing surface that concentrates bolt pressure onto the gasket’s contacting area. This design creates a tighter seal, perfect for medium‑ to high‑pressure systems, and is often used in oil & gas, chemical plants, and power applications. ### Flat Face (FF) A flat face flange has a smooth, even surface that allows the gasket to make full contact. Ideal for low‑pressure, low‑temperature pipelines and materials like cast iron, it reduces stress during bolt tightening. ## **Performance at a Glance** To help you compare quickly, here’s a side-by-side look at how raised face and flat face flanges stack up in terms of sealing strength, pressure range, and best use cases. | **Feature** | **RF Flange** | **FF Flange** | | --- | --- | --- | | Sealing Pressure | Higher (focused force) | Lower (distributed force) | | Pressure Range | Medium to high | Low | | Suitable Materials | Carbon, stainless, alloy steels | Cast iron, brittle materials | | Common Uses | Industrial piping, high‑pressure systems | HVAC, water treatment, instrument lines | ## **Does The Difference Matter?** Choosing the right flange face isn’t just about following a standard — it directly affects sealing strength, gasket compatibility, and long-term reliability. Raised face flanges focus the sealing force on a smaller area, making them more effective under pressure. Flat face flanges spread out the load and are better suited for fragile materials like cast iron. RF flanges are generally easier to torque accurately and handle more stress, while FF flanges help prevent flange surface warping in lower-pressure setups. ## **Long’an’s Advantage in Both Types** Raised face or flat face, each type needs to be [made with precision](https://www.longanflange.com/wp-content/uploads/wp-mfa-exports/page/manufacturing.md). At Long’an, we machine every sealing surface in-house and tailor each flange to your pressure, gasket, and material requirements — so it fits right the first time. - Full in-house CNC machining to match precise RF heights or flat face specs. - We match each flange with the right gasket type—spiral-wound, ring, or full-face—based on what your system requires. - Material traceability and ERP-monitored production ensure consistency in all flanges. A technical challenge often arises when boiler‑grade cast‑iron headers meet stainless pipework. Long’an solves this by customizing flange faces to align exactly, ensuring secure seals without field modifications. ## **Which Seal Should You Choose?** Not sure which way to go? Here’s a quick breakdown to help you decide based on your system requirements. - **Go RF** when pressure is above standard, or when using steel materials in critical lines. - **Pick FF** for low-pressure, fragile material setups like cast iron or instrument manifolds. And always match flange face types—RF to RF or FF to FF—per ASME standards, or risk leakage. ## **Raised Face Flange vs Flat Face: Conclusion** At Long’an Flange, our experience in manufacturing stainless steel flanges shows that choosing between raised face vs flat face isn’t just about the face—it’s about the whole system’s reliability. We engineer both RF and FF flanges with precision, offering guidance every step of the way. [Talk to our engineers today](https://www.longanflange.com/wp-content/uploads/wp-mfa-exports/page/contact.md) to find the seal that fits your specifications. Request your flange solution now!