Weldolets, Sockolets, Threadolets, Branch Fittings - Projectmaterials

SOCKOLET

A Sockolet fitting is a type of branch connection used in piping systems to provide an outlet from a larger (main) pipe to a smaller (branch) pipe. Likewise Weldolets, Sockolets are used to make a 90-degree pipe branch. Sockolets may be “size on size” or “reducing”. Sockolet is a member of the O’let family, which includes various fittings designed for different connection needs. The Sockolet is specifically designed for socket weld connections, which distinguishes it from other types of branch fittings, such as Weldolets (designed for butt-weld connections) or Threadolets (designed for threaded connections).

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A Sockolet is essentially similar to a Weldolet, with the difference that the branch pipe is connected to the run pipe, via the Olet, with a socket weld connection that shall conform to ASME B16.11. 

Fillet welds are used to connect the branch pipe to the branch side of the Sockolet. On the pipe run side, a Sockolet requires a welded connection.

Key advantages of Sockolets:

• Socket Weld Connection: Sockolets are used to create a 90-degree branch connection and are welded into place via a socket weld. The branch pipe is inserted into the Sockolet’s socket and then welded around the top to secure it. This method provides a strong, leak-proof connection.
• High-Pressure Applications: Sockolets are well-suited for high-pressure applications where the fluid dynamics require a smooth transition and minimal turbulence at the connection points.
• Size and Pressure Ratings: They are available in a range of sizes and pressure ratings to match the requirements of various piping systems, ensuring compatibility with the main pipe’s diameter and wall thickness.
• Material Variability: Like other O’lets, Sockolets are manufactured in various materials, including carbon steel, stainless steel, and alloy steel, to cater to different environmental conditions and fluid types in the piping system.
• Reduced Stress Concentration: The design of a Sockolet aims to minimize stress concentration at the branch connection, enhancing the overall integrity and longevity of the piping system.

SOCKOLET VS. WELDOLET

Sockolets belong to the “socket fittings” family (forged fittings) and are available in classes #, #, and #, whereas Weldolets are classified as buttweld fittings. Sockolets are used for lower pressure applications, and smaller pipe diameters, than Weldolets.

The key differences between Weldolets and Sockolets are:

Connections Methods

• Sockolet: Designed for socket weld connections. The branch pipe is inserted into the Sockolet’s socket and then welded around the top. This method is typically used for smaller pipe diameters and provides a smooth and compact connection.
• Weldolet: Made for butt-weld connections. It is welded onto the side of the main pipe and the end of the branch pipe, allowing for a direct and structurally sound connection. Weldolets are used for a wider range of pipe sizes and can handle significant changes in pipe diameter.

Applications

• Sockolet: Suited for high-pressure and high-temperature applications where space is limited and a leak-proof connection is essential. The socket weld connection offers excellent strength and is commonly used in smaller bore piping on projects that require a reliable seal.
• Weldolet: More versatile in application, Weldolets can be used in both high-pressure and low-pressure systems. They are preferred for creating branch connections where the branch size is significant compared to the main pipe. Due to their design, they are better suited for withstanding stress and are often used in industries such as oil and gas, petrochemical, and water treatment.

Sizes

• Sockolet: Generally used for smaller branch connections, typically up to 2 inches in diameter. They are rated for high-pressure applications, often in alignment with the pressure ratings of the socket weld fittings.
• Weldolet: Can accommodate a broader range of sizes, from very small to very large diameters, making them suitable for a wider variety of applications. Weldolets can also match the pressure ratings of the main pipe, allowing for their use in both high and low-pressure systems.

Stress Distribution

• Sockolet: The socket weld connection of a Sockolet minimizes stress concentration, making it suitable for applications where the integrity of the piping system is critical under high pressure.
• Weldolet: Designed to minimize stress concentrations at the branch connection through its contoured, integrally reinforced design. This makes Weldolets particularly effective in situations where the branch connection might be subjected to thermal or mechanical stress.

Installation Complexity

• Sockolet: Requires precise fitting and welding inside the socket, which can be more challenging in tight or confined spaces.
• Weldolet: Installation involves preparing the main pipe surface and executing a butt-weld, which can be more labor-intensive but allows for a more versatile application across different pipe sizes and conditions.

THREDOLET

A Threadolet is a type of branch fitting that is used to provide an outlet from a larger pipe to a smaller one. Unlike Weldolets and Sockolets, which are designed for welding, Threadolets facilitate connections via threaded fittings. This characteristic makes Threadolets particularly useful in applications where welding is not feasible or where a detachable connection is preferred for maintenance or operational flexibility.

Thredolets are used for low-pressure 90-degree pipe branches. The branch pipe is screwed on the Thredolet, which is welded on the run pipe. The threading is generally of the NPT type and conforms to the ASME B1.20.1 specification.

Thredolets belong to the “threaded fittings” family (forged fittings) and are available in classes # and #.

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Threadolets are commonly used in low-pressure piping systems where a removable connection might be necessary, such as for instrumentation ports, pressure gauge connections, and smaller branches from main pipes. They are particularly valued in oil and gas, chemical processing, and petrochemical industries, where their ease of installation and maintenance, as well as their adaptability to various environments, make them an ideal choice.

Key Thredolets features:

• Threaded Connection: Threadolets are equipped with female threads to accommodate the male threads of the branch pipe. This enables a secure and leak-proof connection without the need for welding.
• Versatile Applications: Suitable for a wide range of applications, especially in systems where flammable or hazardous materials are present, and hot work (like welding) poses a safety risk.
• Material Compatibility: Available in various materials to match the piping system, including carbon steel, stainless steel, alloy steel, and more, ensuring compatibility with different fluid types and operational conditions.
• Pressure Ratings: Threadolets are designed to withstand the pressure demands of the system they are integrated into, with ratings often matching those of standard pipe fittings for consistency and safety.
• Size Range: They can be used to create branch connections in a broad range of sizes, providing flexibility in designing and retrofitting piping systems.

LATROLET

A Latrolet fitting is a type of branch connection used within piping systems to create a 45-degree lateral connection from a main pipe to a smaller branch pipe. It is part of the family of O’let fittings, which includes various specialized fittings designed for making branch connections in different configurations. Latrolets are specifically engineered for situations where a 45-degree branch is needed, either for a change in the direction of the flow or to connect auxiliary equipment.

Latrolets are commonly utilized in both new construction and retrofitting projects within the oil and gas, petrochemical, power generation, and water treatment industries. Their design makes them particularly useful for adding instrumentation, vents, drains, or other auxiliary connections at a 45-degree angle, facilitating optimal flow dynamics and accessibility.

Latrolets are available with butt weld connections to meet demanding reinforcement requirements or with socket weld/threaded connections in classes # or #.

Key Features:

• Angled Branch Connection: The defining feature of a Latrolet is its ability to create a 45-degree branch, which can be crucial for directional changes in piping systems or for integrating lateral connections efficiently.
• Versatile Connection Types: Latrolets can be manufactured for butt weld, socket weld, or threaded connections, providing flexibility to match the requirements of the piping system and the installation preferences.
• Range of Sizes and Pressure Ratings: They are available in various sizes and pressure ratings, allowing them to be used in a wide range of applications, from low-pressure residential systems to high-pressure industrial settings.
• Material Compatibility: Similar to other O’let fittings, Latrolets are made from a variety of materials, including carbon steel, stainless steel, and alloy steel, to ensure compatibility with the main pipe’s material and the operational environment.

ELBOLET

An Elbolet is a specialized type of branch fitting designed to provide an outlet connection on the curvature of an elbow. It is part of the broader family of O’let fittings, which are used to create integrally reinforced branch connections from a larger (main) pipe to a smaller (branch) pipe. The unique feature of an Elbolet is its ability to be installed on the 90-degree or other curved surfaces of elbows, making it an ideal solution for adding branch connections at these points in a piping system.

Elbolets are commonly used in piping systems that require branch connections directly on elbows, such as in oil and gas, chemical processing, power generation, and water treatment facilities. They are particularly valuable in situations where space constraints or specific flow directions necessitate the use of elbows for branch connections, including instrumentation take-offs, vent lines, or sampling ports.

Elbolets are available with butt weld connections or with socket weld/threaded connections in classes # or #.

If you want to learn more, please visit our website A105 Thread Steel Olet(pt,tr,es).

Key features:

This is my first post, so please comment if you see anything amiss on how or what I present in my question.

My question is regarding Weldolets® and Sockolets® and piping materials in a piping specification. Usually, the forged materials specified for flanges and olets are the same from 0.5" NPS to 24" NPS, for example ASTM A105. But I have a piping specification that doesn’t follow that convention. The general particulars for this pipe spec are design press of 1,480 PSIG @ 100°F, design temp of -10°F/+220°F with a service in fuel gas and gas lift operations. Designed to ASME B31.4/B31.8 (D.F. = 0.72) and a corrosion allowance of 1/16". The flange material is specified but the olet material is not, so I plan to follow the flange material unless there is a reason not to.

Code:

Pipe Size    Pipe Material              Schedule   Flg Material
----------   ------------------------   --------   ------------
0.5" - 2"    API-5L Gr B, SMLS          Sch XS     ASTM A105
3" - 8"      API-5L Gr B, ERW or SMLS   Sch STD    ASTM A105
10"          API-5L X42, ERW or SMLS    Sch STD    ASTM A694 F42
12" - 14"    API-5L X52, ERW or SMLS    Sch STD    ASTM A694 F52
16"          API-5L X52, ERW or SMLS    Sch XS     ASTM A694 F52
18"          API-5L X52, ERW or SMLS    Sch 30     ASTM A694 F52
20"          API-5L X52, ERW or SMLS    Sch XS     ASTM A694 F52
24"          API-5L X52, ERW or SMLS    Sch 30     ASTM A694 F52

All of that is to get to this question regarding the material choices for the Weldolets® and Sockolets®.

For an 18" x 3" Weldolet®, would the material match the flange material associated with the pipe header? For example, the bill of material for that size would specify:

[highlight #FCE94F]WELDOLET, SCH 30 X SCH STD, ASTM A694 F52[/highlight]

But for an 8" x 3" Weldolet®, you would specify:

[highlight #FCE94F]WELDOLET, SCH STD, ASTM A105[/highlight]

Is this correct?

Thank you for your thoughtful consideration.

PositiveRate
I think the weldolet would need to follow the branch pipe material more than the header pipe as the additional welding makes u up the strength difference, but not the branch.

However the pipe size up to 8~" is grade B, so A105 should be good for those sizes. Only if you get a branch connection >8" would you maybe need to look at the A694 spec.

Also maybe you know, but if you're using A694, you need to specify the flanges to MSS-SP-44 for the flanges , not B16.5, and MSS-SP-97 for the branch fittings.

I'm happy to be proved wrong....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it. OK. A-105 is low yield strength at psi. Closely matching wall thicknesses with x52+ isn't going to be easy. It's also better to weld similar strengths. Kind of a large gap from 36 to 52. I always used a pup of x42 in between.

Pretty sure you can still just reference the MSS and the desired strength and leave the actual selection of astm material to the mfgr.


A black swan to a turkey is a white swan to the butcher ... and to Boeing. Positive ...

A very good piping question and very clearly stated !!!! ....... Sadly, this is a rare thing on these august fora

In my opinion, this entire discussion outlines the importance of companies supporting "up-to-date" piping specifications....

My experience has been too many projects just copy and reuse the same decades old piping specifications..

Field engineers should not be making these important design decisions .... The world changes and piping specs must be kept up to date !!

But dismissal of the old grey-beard staff engineer is usually the first target of new MBAs ....



MJCronin
Sr. Process Engineer
The default assumption of reinforcement is usually that the reinforcing material is at least as strong as the header being reinforced, so in my mind matching the higher yield of the two header and branch materials is the inarguably conservative approach.

When I used to do B31.8 work for 2" and smaller branches I would use 3M or XS A105 (or A350 LF2 CL1) olets exclusively regardless of the header yield, but this was meter station work with DF = 0.5 so no reinforcement calcs required by B31.8 for any reasonably large header size. Transmission/distribution companies around here typically do not allow weldolets above 2" but if I was in your position I would start by using your proposed approach until a reputable olet manufacturer told me in writing otherwise. The question also needs to be asked is what does your piping spec say about when / what size do you change from weldolets to reducing tees?

Big weldolets are not often used because they take forever to weld and you end up with so much heat going into the header than you can bend it like a banana.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.