Cost-effective And Easy-to-install Piping Solution
Slip-on flanges provide cost-effective, easy-to-install piping connections, ideal for oil, gas, and water systems with moderate pressure resistance.
Cost-effective And Easy-to-install Piping Solution
Slip-on flanges provide cost-effective, easy-to-install piping connections, ideal for oil, gas, and water systems with moderate pressure resistance.
A straightforward design that balances integral and lap joint flanges, widely used in fluid pipeline systems.
A hubbed steel pipe flange offering reliable connections with easy processing and installation.
Features a small protrusion on the bottom face, creating a dedicated area for gasket placement and improved sealing performance.
Designed with a precision-machined groove, ideal for high-pressure applications with superior sealing using a metal ring gasket.
Slip-On Flange is a ring-shaped fitting slipped over the pipe end and welded on both sides, offering a simple and economical connection. Compliant with ASME B16.5 and DIN standards, it is crafted from carbon steel, stainless steel, and alloys for durability. As of August 19, 2025, it remains a top choice for efficient piping.
The Easy Pipe Flange features a slightly larger bore than the pipe, allowing easy installation and alignment, with pressure ratings up to 300 PSI for Class 150 and 600 PSI for Class 300. Available in sizes from 1/2” to 24”, it suits low to moderate-pressure systems.
Slip-On Flange undergoes hydrostatic and radiographic testing to ensure leak-proof performance. Coated with galvanizing or FBE for corrosion resistance, it operates effectively from -20°C to 400°C, depending on material, making it ideal for oil and gas pipelines.
Compared to weld neck flanges, Slip-On Flange reduces installation time and costs, though it offers less strength for high-pressure applications. Proper welding and alignment are essential for a secure joint. It provides a service life of 15–30 years.
Slip-On Flange addresses challenges like high installation costs and misalignment in industrial piping, delivering an efficient, durable solution for oil, gas, and water treatment systems as of August 2025.
Stainless 316L Slip-on Flange
Slip-on flanges are versatile pipe fittings designed for easy welding and length adjustment, ideal for lower pressure applications.
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.
The SO flange can be divided into SO welding plate flange and SO welding hubbed steel pipe flange.
Its mechanical characteristics are between the integral flange and the looping flange. The structure is simple, and the processing is convenient. So slip on flange welding is widely used in various fluid pipelines. Depends on different face, there are also ranges raised face type and ring type joint face type.
There is a small portion extruded from the bottom face of the slip on flange, this type is raised face slip on flange. The function of this area is to place a gasket seat during installation to get a better sealing performance.
As the pressure ratings bigger, the height of this raised face will be bigger.
A small grooved is machined on the raised face part, this form is called RTJ type, the function of this groove is to place the gasket ring, also applied for sealing, compared to RF type, RTJ is designed for high pressure use.
Slip on flange use slip welding to connect equipment, so either below of name is describing the same flange:
Slip-On flanges or SO flanges are commonly lower in price than weld-neck flanges, and to this effect are a popular choice for our customers.
| Class | Flat Face (FF) | Raised Face (RF) | Ring Type Joint (RTJ) |
|---|---|---|---|
| ANSI 150 | SO Flange ANSI 150 FF (in) | SO Flange ANSI 150 RF (in) | SO Flange ANSI 150 RTJ (in) |
| ANSI 300 | SO Flange ANSI 300 FF (in) | SO Flange ANSI 300 RF (in) | SO Flange ANSI 300 RTJ (in) |
| ANSI 400 | SO Flange ANSI 400 FF (in) | SO Flange ANSI 400 RF (in) | SO Flange ANSI 400 RTJ (in) |
| ANSI 600 | SO Flange ANSI 600 FF (in) | SO Flange ANSI 600 RF (in) | SO Flange ANSI 600 RTJ (in) |
| ANSI 900 | SO Flange ANSI 900 FF (in) | SO Flange ANSI 900 RF (in) | SO Flange ANSI 900 RTJ (in) |
| ANSI 1500 | SO Flange ANSI 1500 FF (in) | SO Flange ANSI 1500 RF (in) | SO Flange ANSI 1500 RTJ (in) |
| ANSI 2500 | SO Flange ANSI 2500 FF (in) | SO Flange ANSI 2500 RF (in) | SO Flange ANSI 2500 RTJ (in) |
Note: The datasheets shown adhere to ASME B16.5, which covers flange dimensions from ½” to 24”. For sizes larger than 24”, please visit our flange datasheets page.
304 Stainless Slip-on flange
SO flanges provide a secure and leak-resistant connection between pipes or fittings in a piping system. The process begins by slipping the flange onto the end of the line, ensuring the flange’s inner diameter matches the pipe’s outer diameter. This allows for a smooth transition and maintains a consistent flow path.
Once the component is positioned correctly, it is then welded to the pipe. The welding creates a strong bond between the flange and the line, ensuring a reliable and durable connection. Moreover, the flange’s flat face provides a sealing surface easily aligned with gaskets or rings to prevent leakage.
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 Slip-On Flange to connect pumps, pipes, valves, and other equipment, often using butt welds, to make a pipework system.
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