Lap joint flanges are also known as Backup flanges, Loose Ring flanges, Loose Hubbed flanges, and Van Stone flanges.
A Stub end Flange or more commonly referred to as lap flanges are used with short ends. The short-end adapter slides over the flange and is welded to the pipe. A lap flange is similar to a slip flange, except that it is flat and has a machining radius at the hole. This allows it to rotate freely around short pieces for easy alignment with the fit flange.
When bolted, the lap flange compresses the short ends into gaskets and other mating surfaces and seals them. Short ends and lapping are commonly used in alloy piping systems. These flanges are usually made of less expensive carbon steel materials because they are not exposed to process fluids. We offer lap flanges in all diameters and pressure classes. Coastal Flanges can provide pipe flanges of all material grades, specifications and sizes.
Lap joint flange (simplified as LTF flange) shape is similar to slip on flange, it has a curved radius at the bore, which can connect with a stub end fittings and slide over the pipe. In this form, the pipe is usually welded to this stub end so the lap joint flange can rotate freely around the stub end.
The advantage of this combination that it will be easy with alignment for the bolt hole, easy to install and uninstall, much more convenient to do examinations and maintenance.
Stud End:
A stub end is always used with a lap joint flange as a backing flange. There are three different types of stub ends, type A, B and C.
Type A stub end can be machined to fit the standard lap joint support flange.
Type B stub end is designed to be used with standard slip on flange.
Either a lap joint flange or slip on flange, the type C stub end can be used
Stub end include long or short pattern length. The end of long pattern is also known as ASA Stub Ends. The short end is used with the larger flanges of ANSI 300 and 600. They are commonly used in most sizes ANSI 900 and above.
Pros:
1. Compatible with frequent dismantling. The pipe can be removed easily and frequently for inspection and cleaning purposes.
2. It is easy to rotate the flanges and align the bolt holes, which simplifies the assembly of large-diameter or unusually stiff pipes.
3. Cost-saving. If the pipe material is alloy steel or stainless steel, when using a lap joint flange, the wetting material consists of a special material and the flange will be carbon steel. Since the flange does not come into contact with the process fluid, it is not affected by the fluid.
4. Recyclable. In systems that are rapidly corroded or corroded, the flange can be recycled for reuse.
Differences Between Lap Joint Flange and Slip On Flange:
1. The slip-on flange is essentially a ring placed over the pipe end. The flange face extends a sufficient distance from the pipe end to allow welding on the inner diameter. The outer diameter of the slip-on flange can also be welded to the rear side of the flange. Compared to the weld neck flange, the slip-on flange has lower material costs and is easier to align.
2. The lap flange is very similar to the slip-on flange. From the outside, it almost looks the same. But looking at the backside, the holes and faces of the lap joint flange have a curved radius to accommodate the lap joint stub end.
3. If type B or type C stub ends are used, the slip-on flange can be used as the lap joint flange.
Carbon steel: ASTM A105, A350 LF2
Stainless steel: A182 F304/F304L/F316/F316L/F321
Alloy steel: ASTM A182, GR F1, F11, F22, F5, F9, F91
Dimensions:
Common Outer Diameters: 1/2'' to 24''
Wall Thickness Schedule: SCH 10, SCH 40, SCH 160
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