If you’ve ever worked with piping systems, valves, or heavy industrial equipment, you’ve definitely run into flanges. And if you’ve come across EN flanges (that’s European Norm flanges for the uninitiated), you might’ve wondered exactly how their connection type works—because cutting corners here can lead to leaks, breakdowns, or way worse on a job site. As someone who’s been supplying EN flanges for over a decade, I field this question all the time: “What’s the big deal about their connection type, anyway?” Let’s break this down like I’d explain it to a new plant technician over a coffee—no stuffy jargon, just real, useful info. EN Flanges
First off, let’s get one thing straight: EN flanges aren’t some random flange type made up by some random supplier. They’re standardized by the European Committee for Standardization (that’s why they’re “EN”)—so their connection type is locked into specific rules, which is why they’re so widely used across Europe and even exported to places like the Middle East, Asia, and parts of the Americas. Unlike old, random flanges that only fit one local pipe, EN flanges are built to match a universal standard, so you can swap them out across brands no problem. That’s the main reason folks go for them, tbh.
Now, the connection type itself—this is where most people get confused, so let’s start with the basics. The core of any flange connection is two flat (well, mostly flat) circular plates, each with matching holes for bolts. You stick a gasket in between them, line up the bolt holes, tighten the bolts down, and boom—sealed connection. But EN flanges have specific specs for how that connection is structured, which splits them into a few common types I deal with every day as a supplier.
Let’s start with the most basic one: EN 1092-1 flat-faced flanges (we just call these “FF” in the business). This is your go-to for low-pressure, non-corrosive systems—like a basic water line in a small factory or a low-grade air pipe. Here, the entire face of the flange is flat, no raised edges. The gasket sits right on that flat surface, and when you tighten the bolts, the flange faces press down evenly on the gasket to create a seal. The catch here is FF flanges need a really good gasket—no rips, no dirt on the faces—because the entire contact area has to do the sealing. I once had a customer call me panicking because their FF flange leaked; turned out their tech dragged the old gasket across the flange face, leaving a tiny grit mark that broke the seal. Lesson learned: even small mess-ups mess with FF connections.
Next up, the most common type I sell: EN 1092-1 raised face flanges (we shorten this to “RF” all the time). This is the workhorse of EN flange connections, used for medium to high pressure—think oil pipelines, chemical processing units, or gas lines. The key difference here is there’s a small, raised circular ring (usually 2mm to 10mm tall, depending on the flange size and pressure rating) in the center of the flange face. That raised ring is what squeezes the gasket, not the entire flat face. Why’s that better? It creates a more concentrated pressure point, so the seal is tighter, and it’s less sensitive to small dirt marks on the flange face. I always tell my customers: if they’re not sure what connection type they need, RF is the safe bet. 9 out of 10 times, that’s what the project specs call for.
Wait, but what if you’re dealing with super corrosive fluids or really high pressure? That’s where EN 1092-1 ring-type joint flanges (RTJ) come in. These are the heavy hitters, usually used in oil and gas refineries or deep-well piping. Instead of a flat face or a raised ring, RTJ flanges have a machined groove on the face that’s shaped like an octagon or an oval. The gasket here is a solid metal ring (usually stainless steel, carbon steel, or even alloy steel) that fits perfectly into that groove. When you tighten the bolts, the flange faces push the metal gasket into the groove, creating a seal that can handle way more pressure and extreme temps than any rubber or synthetic gasket. I don’t sell as many RTJ flanges as RF, but when I do, the projects are massive—like offshore drilling platforms. Those guys don’t mess around with flange connections.
Now, let’s talk about why the EN flange connection type is different from, say, ANSI flanges (the North American standard, for anyone wondering). That’s a question I get all the time, especially from customers who source parts from both sides of the Atlantic. The sizing is different first—EN flanges use metric measurements, while ANSI uses imperial, so the bolt hole spacing is totally off. But more importantly, the pressure ratings and connection tolerances are different. For example, an EN RF flange rated for PN16 (that’s 16 bar, right?) isn’t the same as an ANSI RF flange rated for Class 150. You can’t swap them without major modifications, which is why I make sure every customer tells me which standard they’re working with before I send them anything. No one wants to waste thousands on flanges that don’t fit.
Another thing that matters for the connection type: bolt torque. Tightening EN flange bolts isn’t just “snug them up.” Each connection type has a specific torque spec to get the seal right. For FF flanges, you have to tighten bolts in a crisscross pattern—don’t just do one side at a time, because that’ll warp the flange face and break the seal. For RTJ flanges, you need to use a torque wrench to get each bolt to exactly the right number, because too little torque and you get a leak, too much and you’ll crack the flange or warp the ring. I always send a free torque guide with every bulk order I make—small thing, but it saves my customers so much headache down the line.
Wait, should I mention something about EN 1092-2? Nah, that’s for pipe ends, not the connection type. Most of my customers deal with the EN 1092-1 standard, so that’s what I focus on. And let’s be real, as a supplier, I’ve seen enough bad installs to know that misunderstanding the connection type is the number one cause of flange issues. I had a client last year who used an RTJ flange where an RF was supposed to be, because they thought “more metal = better.” Nope—RTJ flanges are way more expensive, and he didn’t have the right gaskets or tools to tighten them, so he ended up leaking all over his plant floor and had to replace the whole connection a week later. That’s the kind of mistake I try to help customers avoid.
Let’s wrap this up for anyone who’s still reading and going “ok, so what do I need to know as someone looking to buy EN flanges?” First, confirm the project requirements: pressure rating, fluid type, temperature. That’ll tell you which connection type you need (FF, RF, RTJ). Second, make sure the flanges are compliant with EN standards—no knock-offs, because their connection dimensions won’t match up. I’ve seen cheap flanges from no-name suppliers where the RF ring is off by a millimeter, which means the gasket won’t sit right. Third, don’t skip the torque and installation steps—follow the crisscross pattern, use the right tools, and check for leaks after pressure testing.
EN Flanges At the end of the day, the EN flange connection type is all about standardization and reliability. It’s built to work consistently across different systems, which is why it’s still the go-to for industrial projects in Europe and beyond. As a supplier, my job isn’t just to sell flanges—it’s to make sure my customers get the right connection type, the right parts, and the info they need to install them right. If you’re working on a project and aren’t sure which EN flange connection type you need, or if you’ve had issues with flanges leaking or not fitting, reach out— I’m happy to walk through your options, no pressure.
References
- European Committee for Standardization. (2007). EN 1092-1:2007: Flanges and their joints—Circular flanges for pipes, valves, fittings and accessories, PN designated—Part 1: Steel flanges.
- American Society of Mechanical Engineers. (2020). B16.5: Pipe Flanges and Flanged Fittings.
- Hydraulic Institute. (2018). Flange Connection Best Practices for Industrial Piping Systems.
- The European Valve and Fittings Industry Association. (2021). EN Flange Standardization Guide for Manufacturers and End Users.
Hebei Haihao Group Huadian High Pressure Pipe Fittings Co., Ltd.
As one of the most professional en flanges manufacturers and suppliers in China, we are able to meet the needs of the majority of our customers. Please rest assured to wholesale high quality en flanges made in China here from our factory. For price consultation, contact us.
Address: Donglin Industrial Zone, Mengcun County, Cangzhou City, Hebei Province, China
E-mail: haihaohuadian@outlook.com
WebSite: https://www.hhfittings.com/
