Blind Flange is manufactured without a bore and used to blank off the ends of pipes, valves and pressure vessel openings. From a standpoint of internal pressure and bolt loading, blind flanges are of the most highly stressed flange types, especially in the larger sizes. Because most of these stresses are of bending types near the center and there are no standard inside diameters, these flanges are suitable for higher pressure/temperature applications.

All domestic steel pipe blind flanges are made from material forged and machined in USA.

Size & Dimension table for Flanges

A105 - The standard forged carbon steel piping components for ambient and high temperature / pressure systems

SS304 - A common standard for stainless steel due to its malleability, high corrosive resistance weld-ability  

SS316 - A molybdenum stainless steel that provides excellent tensile, creep and stress-rupture strengths at elevated temperatures

Material Description for Flanges

Today we’ll talk about different flanges such weld neck flange, slip on flange and blind flange etc. These are all steel pipe flanges. This is a slip on flange and this is a 2 inch flange, 150 pound. All flanges that we are showing you today for the purpose of this video are 150 pound flanges. 2 inch flange, this is a 2 inch pipe sample, and you see the slip on flange is the easiest one, you just slide it on and then you weld it. This is a raised face flange, and the raised face flange, on the backside of the flange, right here, you can see that has a lip, a 1/16 inch lip. This is also a slip on flange, but this is a flat face, and we are showing you as an example that this does not have a raised face, this is a flat faced flange slip on flange.

This is a 2 inch flange, but this is a threaded pipe flange. You can see the pipe threads here. If you have a 2 inch pipe and you have a thread on it, then you simply thread it in. That’s the only difference between a slip on or a threaded flange. Again, this is also a raised face, so it has a 1/16 lip on the backside. A 150 pound, 2 inch, threaded flange.

This is a socket weld flange. 2 inch, raised face, 150 pound socket weld flange. Remember, all flanges have a stamping here that shows the size, the pressure rating, the country of origin, the specification, the material. A socket weld flange, if you can see right here, has a little socket. The pipe goes in here and it fits in the socket and then you can weld it. You can see from the backside, this is a standard schedule pipe, this is a standard bore socket weld flange, and it’s very flush from the backside.

On the socket weld flange, you have to specify the pipe schedule. The pipe schedule, this is a 2 inch nominal pipe, and this is a standard schedule pipe, and this is a standard schedule socket weld flange. The pipe schedule and the bore of the socket weld flange has to match so that there is no raised face, there is no protrusion on the backside. The difference between a socket weld flange that has a bore of schedule 40 or schedule 80 is that this inner bore will change so it matches the bore of the pipe. That’s what you’re trying to do.

Remember, on a socket weld flange, other than specifying if it’s a 150 pound or 300 pound, you also have to mention if it is for a schedule 40, schedule 80, schedule 120, schedule 160, what is the schedule of the pipe where you’re trying to use this socket weld flange.

This is a weld neck flange, this is a very popular flange, a lot of people use it. Again, as the name says, it has a welding neck right here. 150 pound flange, it has four bolts, again, raised face, it has a little lip on the backside, the stamping on the side. The way the weld neck flange is used is you take a pipe, again, this is a 2 inch pipe, and you have to have a bevel. This does not have a bevel, but if you are installing, you’ll have a bevel, and then you just butt it up right like this and then you make a weld. That’s how it is installed and it’s called a weldneck flange, this is a welding neck of the flange.

On the weldneck also, you have to specify the bore, so if you specify the schedule, whether it’s for schedule 40, schedule 80 and so on, that will determine the size of the bore here. Again, this is also, that once you weld it, you don’t want your pipe to be thicker than the flange; that will not be good for the flow. Once you specify the right schedule of the flange that matches the schedule of the pipe, if you look from the inside, it will be almost flush. You won’t be able to see any edge sticking out. A weld neck pipe flange.

This is a lap joint flange. The difference between a lap joint flange and a slip on flange, I want to show you a slip on flange, which looks very similar. From the outside, it almost looks like the same. But you look on the backside, it has a little radius and a little end right here. Some people confuse it that this is a flat faced flange. It is not. If you look at the difference, if you just look at the backside, you will see that this is different because it has a little radius. I’ll show you right now why it has a little radius, that lap joint flange.

For example, I have the same flange in stainless steel, this is a stainless steel 304 flange. Whenever you’re using a lap joint flange, you use a stub end. The radius is for the stub end, so you do like this and that’s why it’s called a lap joint flange. You need to have a stub end and that is the purpose of that little radius right there.

This is a blind flange, and as the name says, there is no bore in it, just a blind flange. Again, 2 inch, 150 pound, blind flange, no bore in it. This is a 2 inch one. Again, it’s hard to see how the 2 inch fits on it, but the outer diameter matches what a 2 inch flange is.

This is another example of a stainless steel flange. We carry both carbon steel, stainless steel, nickel alloys flanges and this is a 304 flange; it’s also available in 316. This is A105 forged material also available in A105 normalized, you just have to specify what flange you want. Thank you.