Flexible And Cost-effective Piping Solution
Lap joint flanges offer flexible, cost-effective piping connections with easy alignment, ideal for petrochemical and water systems with corrosion resistance.
Flexible And Cost-effective Piping Solution
Lap joint flanges offer flexible, cost-effective piping connections with easy alignment, ideal for petrochemical and water systems with corrosion resistance.
Lap Joint Flange is a two-part fitting combining a stub end and a loose backing flange, designed for easy alignment and disassembly in piping systems. Compliant with ASME B16.5 and DIN standards, it is made from carbon steel, stainless steel, and alloys for durability.
The Flexible Pipe Flange allows the flange to rotate, simplifying bolt hole alignment during installation, and is ideal for systems requiring frequent maintenance. Available in sizes from 1/2” to 48” with pressure ratings up to 1500 PSI, it pairs with a stub end for corrosion resistance.
Lap Joint Flange undergoes hydrostatic and dimensional testing to ensure reliability. Its design supports temperatures from -20°C to 400°C, depending on material, and is coated with galvanizing or FBE to enhance corrosion resistance, making it suitable for petrochemical applications.
Compared to weld neck flanges, Lap Joint Flange offers cost savings and flexibility, especially in corrosive environments, as the stub end takes the corrosion load. Proper installation with aligned bolts and gaskets ensures a tight seal. It boasts a service life of 20–35 years.
Lap Joint Flange addresses challenges like misalignment and corrosion in industrial piping, providing an adaptable, durable solution for petrochemical, water treatment, and power generation systems.
A lap-joint flange is a two-component assembly, with a stub end that has a lap-joint ring flange placed over it.
Lap Joint flanges are sometimes referred to by other names, including:
Lap joint flange is used with a lap joint stub end fitting. Lap joint flange is similar to a slip-on flange, but with two differences. The radius and the flat face, both allow the flange to secure against the stub end fitting. This is useful where alignment of bolt holes is difficult, such as with spools to be attached to flanged nozzles of vessels. A lap joint is used in low pressure applications and not suitable where high external of heavy loads are present.
These flanges are always used with either a stub end or taft which is butt welded to the pipe with the flange loose behind it. This means the stub end or taft always makes the face. The lap joint is favoured in low pressure applications because it is easily assembled and aligned. To reduce cost these flanges can be supplied without a hub and/or in treated, coated carbon steel.
Lap joint flanges are usually used in low pressure applications and are not suitable when there are high loads on the flange pair. Some types of piping require the use of lap joint flanges. For example, metallic pipe that has been plastic lining may have lap joint flanges.
Using lap joint flanges might be an option for saving costs when the piping is made of exotic materials. By using a lap joint flange, the wetted materials would consist of the exotic materials and the flange would be carbon steel. Since the flange doesn’t ever come in contact with the process fluid, it would not be affected by the fluids.
Dimensions on the lap joint flange are similar to weld neck, slip on or socket weld flanges. The backing flange has the same number of bolt holes, size and thickness of a weld neck or slip on flange.
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.
The lap joint stub end is butt welded to the pipe, while the lap joint flange is slid onto the pipe before the final welding takes place. The flange has a raised flat portion called the lap, which allows it to overlap with the flanged portion of the stub end, creating a tight seal.
Lap joint flanges are known for their ease of installation and cost-effectiveness. They provide flexibility and can accommodate slight misalignment or movement between the pipe and the flange. However, they are not as strong as other types of flanges, such as welding neck or slip-on flanges.
It's important to note that lap joint flanges should not be used in applications with high temperatures or high pressures, as they may not provide the necessary strength and sealing capabilities. Consulting with a qualified engineer or referring to relevant standards and guidelines is recommended when selecting the appropriate flange type for a specific application.
Lap joint flange with stub end
Lap joint flange is typically used for low pressure application.
It is not suitable when the flange pair need to bear high loads. Some pipes required to use this type flange, like a metal pipe already lined with plastic may have to use lap joint flanges.
A lap joint flange consists of two main components:
Flat Face Flange: The flat face flange is the main body of the lap joint flange. It has a flat surface with bolt holes to secure the flange to the mating flange or pipe.
Stub End: The stub end is a short piece of pipe with a lap joint configuration. It slides over the pipe end and allows the flange to rotate freely, providing flexibility during alignment.
The lap joint flange is typically used with a gasket to ensure a leak-proof joint between the flanges.
Lap joint flanges play a crucial role in various industries, offering a practical and cost-effective solution for pipe connections that require easy assembly and disassembly. Their design allows for flexibility during alignment, making them suitable for a wide range of applications in the petrochemical, oil and gas, water treatment, food and beverage, and chemical processing industries. When it comes to ensuring efficient and reliable pipe connections, lap joint flanges prove to be an essential component in modern piping systems.
The datasheets we have on this site are shown below. For simplicity sake, only datasheets that adhere to B16.5 are shown. ASME B16.5 covers flange dimensions from ½” to 24”. For sizes larger than this (ASME B16.47 Series A & B), please visit our flange datasheets page.
| Class | Flat Face |
|---|---|
| ANSI 150 | Lap Joint, ANSI Class 150 (in) |
| ANSI 300 | Lap Joint, ANSI Class 300 (in) |
| ANSI 400 | Lap Joint, ANSI Class 400 (in) |
| ANSI 600 | Lap Joint, ANSI Class 600 (in) |
| ANSI 900 | Lap Joint, ANSI Class 900 (in) |
| ANSI 1500 | Lap Joint, ANSI Class 1500 (in) |
| ANSI 2500 | Lap Joint, ANSI Class 2500 (in) |
304 Stainless Lap joint flange
By using lap joint flanges, work can be simplified in situations that require frequent and rapid disassemble and assembly during the operation of a plant.
The ability to spin that backing flange compensates for misalignment of the bolt holes during assembly.
Simplifies installation, maintenance, and repair tasks, reducing downtime and overall costs.
Accommodates angular misalignment of pipes, ensuring leak-proof joints.
Reusable design reduces replacement costs, ideal for frequent disassembly applications.
Made from stainless steel or coated carbon steel for long-term reliability in corrosive environments.
Explore Lap Joint Flange with targeted long-tail keywords for specifications, applications, and alignment solutions.
Note: Lap Joint Flange meets ASME and DIN standards, ensuring reliable performance. Contact suppliers for specs.
The most common type, featuring a raised sealing surface that concentrates the bolting force on a smaller area.
Has a flat sealing surface, commonly used with cast iron flanges and for low-pressure applications.
Features a groove for metal ring gaskets (oval or octagonal), providing metal-to-metal sealing.
Features matching tongue and groove surfaces, providing self-alignment and confined gasket area.
Flange faces have to be smooth enough to ensure a tight, leak-free seal for bolted flanges.
| Flange Face Type | Flange Face Type | Flange Face Type |
|---|---|---|
| Type A: flat face | Type D: groove face | Type G: O Ring recess |
| Type B: raised face | Type E: spigot | Type H: O Ring groove |
| Type C: tongue face | Type F: recess |
| ASME B16.5 | Pipe Flanges NPS 1/2 - 24 |
| ASTM A105 | Forged Carbon Steel |
| ASTM A350 LF2 | Low-Temperature Service |
| ASTM A182 | High-Temperature Service |
| ASTM A694 | High-Pressure Transmission |
| DIN EN 1092-1 | European Standard PN 2.5-400 |
Most commonly used, forged with machined surfaces
Corrosion resistant, grades 304, 316, etc.
High-temperature and high-pressure applications
Cast iron, aluminum, brass, bronze, plastic
| Material Category | Fittings (ASTM Grade) | Flanges (ASTM Grade) | Valves (ASTM Grade) | Bolts & Nuts (ASTM Grade) |
|---|---|---|---|---|
| Carbon Steel | A234 Gr WPA | A105 | A216 Gr WCB | A193 Gr B7 A194 Gr 2H |
| A234 Gr WPB | A105 | A216 Gr WCB | ||
| A234 Gr WPC | A105 | A216 Gr WCB | ||
| Carbon Steel
Alloy (High-Temperature) |
A234 Gr WP1 | A182 Gr F1 | A217 Gr WC1 | A193 Gr B7 A194 Gr 2H |
| A234 Gr WP11 | A182 Gr F11 | A217 Gr WC6 | ||
| A234 Gr WP12 | A182 Gr F12 | A217 Gr WC6 | ||
| A234 Gr WP22 | A182 Gr F22 | A217 Gr WC9 | ||
| A234 Gr WP5 | A182 Gr F5 | A217 Gr C5 | ||
| A234 Gr WP9 | A182 Gr F9 | A217 Gr C12 | ||
| Carbon Steel
Alloy (Low-Temperature) |
A420 Gr WPL6 | A350 Gr LF2 | A352 Gr LCB | A320 Gr L7 A194 Gr 7 |
| A420 Gr WPL3 | A350 Gr LF3 | A352 Gr LC3 | ||
| Austenitic Stainless Steel | A403 Gr WP304 | A182 Gr F304 | A182 Gr F304 | A193 Gr B8 A194 Gr 8 |
| A403 Gr WP316 | A182 Gr F316 | A182 Gr F316 | ||
| A403 Gr WP321 | A182 Gr F321 | A182 Gr F321 | ||
| A403 Gr WP347 | A182 Gr F347 | A182 Gr F347 |
ASTM standards define the specific manufacturing process of the material and determine the exact chemical composition of pipes, fittings and flanges, through percentages of the permitted quantities of carbon, magnesium, nickel, etc., and are indicated by "Grade".
The usual materials of flanges include stainless steel, carbon steel, aluminum and plastic. The choice of the material largely depends on the purpose of the flange. For example, stainless steel is more durable and is necessary for heavy use. On the other hand, plastic is more feasible for use in the home because of its reasonable price and easy installation. The materials used for flanges are under the designation of the American Society of Mechanical Engineers.
The most common materials for pipe flanges (forged grades) are: ASTM A105 (carbon steel high temperature to match A53/A106/API 5L pipes), A350 Grades LF1/2/3 (carbon steel low temperature to match A333 pipes), A694 Grades F42 to F80 (high yield carbon steel to match API 5L pipe grades), ASTM A182 Grades F5 to F91 (alloy steel flanges to match A335 pipes), A182 Grade F304/316 (stainless steel flanges to match A312 SS pipes), A182 Gr. F44/F51/F53/F55 (duplex and super duplex to match A790/A928 pipes) and various nickel alloy grades (Inconel, Incoloy, Hastelloy, Monel).
The material qualities for these flanges are defined in the ASTM standards.
Metal flanges are classified from 150 to 2500 # rating for different pressure applications.
Incoloy 825 Flange
Industries Using
The basic application of the Lap Joint Flange to connect pumps, pipes, valves, and other equipment, often using butt welds, to make a pipework system.
Slip-on flanges provide cost-effective, easy-to-in...
Welding neck flanges provide high-strength, high-p...
Blind flanges offer reliable end sealing for indus...
Socket weld flanges offer durable, high-pressure p...
Threaded flanges offer easy, no-weld piping connec...