Domestic Lap Joint Flanges

Lap Joint Flanges have all the same common dimensions as any other flange named on this website however it does not have a raised face. Lap Joint Flanges are used in conjunction with "Lap Joint Stub Ends". These flanges are nearly identical to Slip On flanges with the exception of the radius at the intersection of the flange face and the bore in order to accommodate the flanged portion of the Stub End. Their pressure-holding ability is little, if any, better than that of Slip On flanges and the fatigue life for the assembly is only one tenth that of Welding Neck flanges. Lap Joint Flanges may be used at all pressures and are available in a full size range. These flanges slip over the pipe, and are not welded or otherwise fastened to it. Bolting pressure is transmitted to the gasket by the pressure of the flange against the back of the pipe lap (Stub End).

Lap Joint flanges have certain special advantages including:

• Freedom to swivel around the pipe facilitates the lining up of opposing flange bolt holes.
• Lack of contact with the fluid in the pipe often permits the use of inexpensive carbon steel flanges with corrosion resistant pipe.
• In systems which erode or corrode quickly, the flanges may be salvaged for re-use.

Domestic Lap Joint Flanges are made from material that is 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

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.