Carbon Steel Stub End

A carbon steel stub end is a robust pipe fitting made from strong carbon steel, ensuring seamless and leak-proof connections in piping systems.

The stub end is available with us in different specifications, which find applications in a piping system to allow quick disconnection of the particular section involved.

Features of Carbon Steel Stub End

Carbon steel stub ends offer several key features that make them a popular choice for pipe connections:

1. Material Composition: Carbon steel stub ends are made from high-quality carbon steel, which provides excellent strength, durability, and corrosion resistance.

2. Smooth Inner Surface: The inner surface of the stub end is designed to be smooth and free of any irregularities, ensuring a seamless flow of fluids and minimizing pressure drop.

3. Flanged Connection: Carbon steel stub ends come with a flanged connection, allowing for easy and secure attachment to the pipe without the need for welding.

4. Variety of Sizes: These fittings are available in various sizes to accommodate different pipe diameters and applications.

Applications of Carbon Steel Stub End

Carbon steel stub ends find wide-ranging applications in various industries, including:

1. Oil and Gas Industry

In the oil and gas industry, carbon steel stub ends are commonly used for connecting pipes in oil refineries, offshore platforms, and pipelines. Their corrosion resistance and high strength make them suitable for handling various hydrocarbons.

2. Petrochemical Plants

Petrochemical plants utilize carbon steel stub ends in their piping systems for transporting chemicals and petrochemical products. The smooth inner surface of the stub end ensures the efficient flow of corrosive substances.

3. Power Generation Facilities

In power generation facilities, carbon steel stub ends are employed in steam and water distribution systems. The flanged connection allows for quick and easy maintenance of critical components.

4. Water Treatment

Water treatment plants utilize carbon steel stub ends for connecting pipes in water distribution networks and treatment processes. The durability of these fittings ensures long-term reliability in water handling.

5. Industrial Processing

Carbon steel stub ends are widely used in various industrial processing applications, including chemical processing, food and beverage, and pharmaceuticals. Their versatility and corrosion resistance make them suitable for handling different substances.

Benefits of Carbon Steel Stub End

1. Corrosion Resistance

Carbon steel stub ends offer excellent corrosion resistance, making them ideal for use in corrosive environments and harsh operating conditions.

2. Easy Installation

The flanged connection of carbon steel stub ends allows for easy and quick installation without the need for welding, reducing labor and installation costs.

3. Long Service Life

With their high-quality material and robust construction, carbon steel stub ends can provide a long service life with minimal maintenance requirements.

4. Compatibility

Carbon steel stub ends are compatible with a wide range of piping materials, making them versatile and suitable for various piping systems.

Carbon steel stub ends are essential components in piping systems across diverse industries. Their material strength, corrosion resistance, and easy installation make them a reliable choice for connecting pipes in various applications. From oil and gas to water treatment, these fittings play a vital role in ensuring efficient and leak-free pipe connections.

FAQs (Frequently Asked Questions)

1. Q: Can carbon steel stub ends be used with other types of flanges?
   A: Yes, carbon steel stub ends are compatible with various types of flanges, providing flexibility in piping connections.

2. Q: Are carbon steel stub ends suitable for high-pressure applications?
   A: Carbon steel stub ends are commonly used in low to medium-pressure applications. For high-pressure systems, heavy-duty flanges may be recommended.

3. Q: Do carbon steel stub ends require special maintenance?
   A: Carbon steel stub ends are known for their durability and low maintenance requirements, making them a cost-effective choice for long-term use.

4. Q: Can carbon steel stub ends handle both liquids and gases?
   A: Yes, carbon steel stub ends are suitable for handling both liquids and gases, making them versatile for various industrial processes.

5. Q: Can carbon steel stub ends be used in underground piping systems?
   A: Yes, carbon steel stub ends can be used in underground piping systems as they offer excellent corrosion resistance and long-term reliability.

Third-party inspection companies conduct meticulous inspections.

Short stub end 40" SCH STD ASTM A234 Gr WPB ASME B16.9

Stu bend geometry

In piping systems, a stub end is a crucial component used for connecting pipes of different materials and sizes. It provides a convenient and cost-effective solution for achieving a leak-free joint without the need for welding. In this article, we will explore the geometry, types, and applications of stub ends, shedding light on their significance in various industries and projects.

The Stub End, which essentially a short length of pipe, which has one end that is flared outwards and the other end prepared to be welded to pipe of the same Nominal Pipe Size (NPS), material and of a similar wall thickness. The Lap Joint Flange, which is a ring backing Flange and it is very similar in geometry to the Slip-on Flange.

Stub ends are mechanical joints that comprises of two components.

This type of flanged connection was also referred to as “Van Stone” or “Vanstone flare laps”, however this is an historic terminology and very rarely used technically or commercially.

Stub Ends assembly

For packing of carbon steel flanges with painting,we would use the bubble wrap to protect the painting.For flanges without painting or oiled with long-term shipment,we would suggest client to use the anti-tarnish paper and plastic bag to prevent the rust.

Stub ends and lap joint flanges can be assembled following this process:

• The Lap Flange is slipped over and onto the Stub end Flange.
• The Stub End Flange is then welded onto a pipe spool, using an approved Welding. Procedure Specification (WPS), by a qualified Welder. The Lap Joint Flange, backing Flange, can revolve around the Stub End, which is now attached to the piping spool.
• The bolt holes of the Lap Joint Flange can now be orientated and aligned with the bolt holes of a mating Flange of the same ASME designate rating and NPS.
• The Lap Joint Flange can be mated to any Flange covered in ASME B16.5, Weld Neck, Slip On, Threaded, Socket Weld, another Lap Joint Flange.

It can also be mated to a fabricated plate Flange with compatible, bolting dimensions.

This means that instead of

Duplex Stub End and a Duplex Lap Joint, you could have Duplex Stub End and Carbon Steel Lap Flange.

Or you could have Stainless Stub End and Carbon Steel Lap Flange. There are other bimetallic combinations that result in a flange assembly that is commercially cheaper.

During recent years the price differential between Duplex/Stainless Steel and Carbon Steel has narrowed and this practice on large Projects has become less common, however a cost difference always exists (the higher the NPS and the length of the pipeline / piping system, the higher the saving). On the other hand, the warehousing cost of one single component, i.e. a Weld Neck Flange, requires less shelf space than the cost of warehousing a Lap Joint and a Stub End. End Users and Contractors shall determine the actual convenience of using stub ends, considering all these factors and generally the commercial advantage is still valid and it may suit certain situation, especially in “brownfield” modifications.

Types of Stub Ends

Stub end are offered in three different ways, type A, B and C. Type A and B stub end are similar to forged fittings, such as elbows and tees, and type C stub end are made in customized sizes.

Stub ends are manufactured in three different types and two standard length.

Type “A”: this type is produced and machined to fit lap joint flanges.The mating surfaces of the stub end and the lap joint flange have a matching profile and surface. The lap thickness of type A stub ends is > = the minimum wall thickness of the connected pipe. The outside the stub end and the lap joint flange have a matching profile and surface. The lap thickness of type A stub ends is > = the minimum wall thickness of the connected pipe. The outside corner of type A has a radius to accommodate the lap join flange, whereas the inside corner is squared.

Type “B”: this type of stub ends is suited for standard slip-on flanges acting as lap-joint flanges. The lap thickness of type B stub ends is >= the minimum WT of the connecting pipe. The lap of these type of stub ends has generally a serrated face. To ensure tight joints, chamfers on the ID side of the flange are required.

Type “C”: this last type can be used both with lap joint and slip-on backing flanges and are fabricated out of pipes. The lap of C-type stub ends is flared over and the lap thickness is 75% of the connecting pipe WT. Type C has a short fillet outer radius able to host any back up flange.

Type “CS”: this type is similar to “C” with the difference that the lap face has concentric serrations machined during the manufacturing process.

Common Types and Lengths

There are two main types of stub ends commonly used in piping systems:

1. Long Pattern Stub End: A long pattern stub end has a longer length compared to the pipe it is attached to. It is designed to be used with standard lap joint flanges. The long pattern allows for easier alignment and welding of the lap joint flange, making it suitable for applications where frequent disassembly is required.
2. Short Pattern Stub End: A short pattern stub end has a length that is similar to the pipe it is connected to. It is used with slip-on flanges, where the stub end slides over the pipe and is welded in place. The short pattern stub end is ideal for applications where space is limited, and the flange needs to be close to the end of the pipe.

Both long pattern and short pattern stub ends are available in various materials such as stainless steel, carbon steel, alloy steel, and others, making them suitable for different industrial applications. They provide a cost-effective and reliable solution for connecting pipes to flanges in piping systems.

Stub ends dimensions and weight

Dimensions and manufacturing tolerances are covered in ASME B16.9 – Butt Weld Fittings and MSS-SP-43 (JIS B2312, JIS B2313 may also apply).

Stub End come in three standard lengths, MSS SP43 or ANSI B16.9 short and long pattern. Short pattern stub ends are mostly used for flanges from class 300 to class 600 and above. Besides these standard types, End-Users and contractors can require stub ends with non-standard lengths to suit specific project’s requirement. This will of course come at an additional cost.

Ends/Face lap finishing

ASME B16.25 END WELDING BEVEL as right

The following types of ends may be ordered:

Beveled Ends (generally ASME B16.25)
Squared Ends
Flanged Ends
Victaulic Grooves
Threaded Ends (Male Only)

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Standard

Pipe fitting dimensions are in either metric or Standard English.

Because pipe fitting covers Pipe Fitting Dimensions several aspects, only the most common pipe fitting sizes can be given here. The most applied version is the 90° long radius and the 45° elbow, while the 90° short radius elbow is applied if there is too little space. The function of a 180° elbow is to change direction of flow through 180°. Both, the LR and the SR types have a center to center dimension double the matching 90° elbows. These fittings will generally be used in furnesses or other heating or cooling units.

Some of the standards that apply to buttwelded fittings are listed below. Many organizations such as ASME, ASTM, ISO, MSS, etc. have very well developed standards and specifications for buttwelded fittings. It is always up to the designer to ensure that they are following the applicable standard and company specification, if available, during the design process.

Some widely used pipe fitting standards are as follows:

ASME: American Society for Mechanical Engineers
This is one of the reputed organizations in the world developing codes and standards.
The schedule number for pipe fitting starts from ASME/ANSI B16. The various classifications of ASME/ANSI B16 standards for different pipe fittings are as follows:

• ASME/ANSI B16.1 – 1998 – Cast Iron Pipe Flanges and Flanged Fittings
• ASME/ANSI B16.3 – 1998 – Malleable Iron Threaded Fittings
• ASME/ANSI B16.4 – 1998 – Cast Iron Threaded Fittings
• ASME/ANSI B16.5 – 1996 – Pipe Flanges and Flanged Fittings
• ASME/ANSI B16.11 – 2001 – Forged Steel Fittings, Socket-Welding and Threaded
• ASME/ANSI B16.14 – 1991 – Ferrous Pipe Plugs, Bushings and Locknuts with Pipe Threads
• ASME/ANSI B16.15 – 1985 (R1994) – Cast Bronze Threaded Fittings
• ASME/ANSI B16.25 – 1997 – Buttwelding Ends
• ASME/ANSI B16.36 – 1996 – Orifice Flanges etc.

ASTM International: American Society for Testing and Materials
This is one of the largest voluntary standards development organizations in the world. It was originally known as the American Society for Testing and Materials (ASTM).

• ASTM A105/A105M – Specification for Carbon Steel Forgings for Piping Applications
• ASTM A234/A234M – Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service
• ASTM A403/A403M – Specification for Wrought Austenitic Stainless Steel Piping Fittings
• ASTM A420/A420M – Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Low-Temperature Service

AWWA: American Water Works Association

AWWA About – Established in 1881, the American Water Works Association is the largest nonprofit, scientific and educational association dedicated to managing and treating water, the world’s most important resource.

• AWWA C110 – Ductile-Iron and Gray-Iron Fittings, 3 Inch Through 48 Inch (75 mm Through 1200 mm), for Water and Other Liquids
• AWWA C208 – Dimensions for Fabricated Steel Water Pipe Fittings

ANSI: The American National Standards Institute

ANSI is a private, non-profit organization. Its main function is to administer and coordinate the U.S. voluntary standardization and conformity assessment system. It provides a forum for development of American national standards. ANSI assigns “schedule numbers”. These numbers classify wall thicknesses for different pressure uses.

MSS STANDARDS: Manufacturers Standardization Society
The Manufacturers Standardization Society (MSS) of the Valve and Fittings Industry is a non-profit technical association organized for development and improvement of industry, national and international codes and standards for: Valves, Valve Actuators, Valve Modification, Pipe Fittings, Pipe Hangers, Pipe Supports, Flanges and Associated Seals

• MSS SP-43 – Wrought Stainless Steel Butt-Welding Fittings Including Reference to Other Corrosion Resistant Materials
• MSS SP-75 – Specifications for High Test Wrought Buttwelding Fittings
• MSS SP-73 – Brazing Joints for Copper and Copper Alloy Pressure Fittings
• MSS SP-83 – Class 3000 Steel Pipe Unions, Socket-Welding and Threaded
• MSS SP-97 – Integrally Reinforced Forged Branch Outlet Fittings — Socket Welding, Threaded, and Buttwelding Ends
• MSS SP-106 – Cast Copper Alloy Flanges and Flanged Fittings Class 125,150, and 300
• MSS SP-119 – Factory-Made Wrought Belled End Socket Welding Fittings

Difference between “Standard” and “Codes”:

Piping codes imply the requirements of design, fabrication, use of materials, tests and inspection of various pipe and piping system. It has a limited jurisdiction defined by the code. On the other hand, piping standards imply application design and construction rules and requirements for pipe fittings like adapters, flanges, sleeves, elbows, union, tees, valves etc. Like a code, it also has a limited scope defined by the standard.

Factors affecting standards: “Standards” on pipe fittings are based on certain factors like as follows:

• Pressure-temperature ratings
• Size
• Design
• Coatings
• Materials
• Marking
• End connections
• Dimensions and tolerances
• Threading
• Pattern taper etc.

BSP: British Standard Pipe

BSP is the U.K. standard for pipe fittings. This refers to a family of standard screw thread types for interconnecting and sealing pipe ends by mating an external (male) with an internal (female) thread. This has been adopted internationally. It is also known as British Standard Pipe Taper threads (BSPT )or British Standard Pipe Parallel (Straight) threads (BSPP ). While the BSPT achieves pressure tight joints by the threads alone, the BSPP requires a sealing ring.

JIS: Japanese Industrial Standards

This is the Japanese industrial standards or the standards used for industrial activities in Japan for pipe, tube and fittings and published through Japanese Standards Associations.

NPT: National Pipe Thread

National Pipe Thread is a U.S. standard straight (NPS) threads or for tapered (NPT) threads. This is the most popular US standard for pipe fittings. NPT fittings are based on the internal diameter (ID) of the pipe fitting.

BOLTS & NUTS

We are manufacturer of Flange bolts & Nuts and supply high quality

• A193 = This specification covers alloy and stainless steel bolting material for pressure vessels, Valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications.
• A320 = Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for Low-Temperature Service.
• A194 = Standard specification for nuts in many different material types.

AN: Here, “A” stands for Army and “N” stands for Navy

The AN standard was originally designed for the U.S. Military. Whenever, a pipe fitting is AN fittings, it means that the fittings are measured on the outside diameter of the fittings, that is, in 1/16 inch increments.

For example, an AN 4 fitting means a fitting with an external diameter of approximately 4/16″ or ¼”. It is to be noted that approximation is important because AN external diameter is not a direct fit with an equivalent NPT thread.

Dash (-) size

Dash size is the standard used to refer to the inside diameter of a hose. This indicates the size by a two digit number which represents the relative ID in sixteenths of an inch. This is also used interchangeably with AN fittings. For example, a Dash “8” fitting means an AN 8 fitting.

ISO: International Organization for Standardization

ISO is the industrial pipe, tube and fittings standards and specifications from the International Organization for Standardization. ISO standards are numbered. They have format as follows:

“ISO[/IEC] [IS] nnnnn[:yyyy] Title” where

• nnnnn: standard number
• yyyy: year published, and
• Title: describes the subject

General standard

Wide variety for all areas of application

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Benefits

Stub ends are essential components used in various industrial applications, particularly in piping systems.

• Simple Preparation: They don't necessitate perfectly flat or parallel cut faces.
• Versatile Metal Pairing: They can join dissimilar metals, like aluminum and copper.
• Thickness Adaptability: They accommodate varying thicknesses, with thinner pieces welded atop, enabling connections even with diaphragms and foils.

The use of stub ends has these two advantages:

Reduces the overall cost of the flanged joint Generally, the lap joint flange is of a lower grade than the material of the stub end and the pipework, thus saving the total weight of high-grade material used for the flanged joint.

Reduces the overall cost of the flanged joint

Generally, the lap joint flange is of a lower grade than the material of the stub end and the pipework, thus saving the total weight of high-grade material used for the flanged joint.

Example:

For an SS316 pipe, instead of using a full 316 welding neck flange, a combination of an SS316 stub end and a carbon steel lap joint flange would do the same exact job, but the total weight of SS316 material would be lower, and the cost as well.

Essentially, stub ends allow to minimize the weight of high-grade material in stainless, duplex, and nickel alloy piping, saving costs. Of course, the bigger the diameter and the class of the flanges, the higher the saving!

Commercial benefits

Commercial advantages are that the Stub End, will be wetted and it must be made of a grade of material that meets the process design and service conditions of the pipeline. However, the Lap Flange is un-wetted and it can be made of a lower grade of material as long as it meets the mechanical strength requirements of the piping systems.

Installation benefits

The “loose” Flange concept of a Lap Joint, is very beneficial during field installation of piping systems. If two spools are to be mated up in the field, having one Flange that can be rotated is very advantageous when aligning the bolt holes, prior to the introduction of the Stub bolt and the accompanying nuts. The facility of easier orientation and alignment of bolt holes, is of particular use it there is a spool that has to be removed frequently, if positive isolation is a process requirement.

Stub Ends limitations

While stub ends offer numerous advantages in piping systems, it's essential to also consider their limitations. Being aware of these limitations helps engineers, designers, and operators make informed decisions when selecting fittings for specific applications. Let's explore some of the key limitations associated with stub ends:

1. Limited Pressure Ratings:

Stub ends, particularly those used in lap joint flange connections, often have lower pressure ratings compared to fully welded or threaded alternatives. This limitation makes them unsuitable for high-pressure applications.

2. Not Suitable for All Materials:

Stub ends are typically made from materials that can be easily formed and welded, such as stainless steel and carbon steel. However, they may not be compatible with certain materials like exotic alloys or non-metallic materials.

3. Vulnerable to Vibration and Movement:

In applications where there is significant vibration, movement, or mechanical stress, stub ends may not provide the same level of reliability as fully welded connections. The slip-on design could potentially lead to loosening or disconnection.

4. Lack of Full Connection Strength:

Unlike fully welded joints, stub ends rely on the lap joint flange for connection strength. This means the joint's integrity is dependent on the quality of the flange and the fasteners used.

5. Potential for Leakage:

Due to the gapped design between the pipe end and the flange, there is a risk of leakage, especially when dealing with fluids or gases under pressure. The joint might require additional sealing measures to prevent leaks.

6. Incompatible with High-Temperature Applications:

Certain materials used for stub ends may not withstand extremely high temperatures, limiting their application in industries where elevated temperatures are common.

7. Restrictions in Pipe Movement:

Stub ends might limit axial pipe movement and thermal expansion compared to fully flexible joints. This could impact the system's ability to accommodate changes in temperature or pressure.

8. Dependency on Flange Quality:

The effectiveness of stub ends relies on the quality of the lap joint flange and the proper installation of fasteners. Any issues with flange quality or installation can compromise the joint's integrity.

9. Not Ideal for Critical Applications:

For applications where a secure and leak-proof connection is paramount, such as those involving hazardous or toxic substances, fully welded joints may be preferred over stub ends.

10. Maintenance and Inspection Challenges:

Stub ends can be harder to inspect and maintain compared to fully welded joints, as visual assessment of the joint's condition may be limited due to the slip-on design.

11. Limited Applications in High-Corrosion Environments:

Stub ends, particularly those made from certain materials, may not be suitable for use in environments with severe corrosion or aggressive chemical exposure.

In conclusion, while stub ends offer various advantages, they also come with specific limitations that need to be carefully considered during the selection and design of piping systems. Engineers and operators should evaluate the specific requirements of each application and assess whether the benefits of using stub ends outweigh their limitations. By making informed decisions, industries can ensure safe, reliable, and efficient piping networks that meet the demands of their operational environments.

Why use Stub Ends?

A stud end and a lap joint flange can be used together as an alternative way to make a flanged connection than welding neck flanges.

Using a stud end and a lap joint flange provides an alternative method for creating a flanged connection, different from welding neck flanges.

The components involved are:

1. Stub End: This is akin to a pipe segment, with one end flared outward and the other prepped for welding to a pipe of the same bore size (NPS = nominal pipe size), material, and wall thickness. Flaring machines are commonly employed to shape the pipe end and then trim it to the desired length.
2. Lap Joint Flange: This flange type facilitates bolting the two pipe segments together, creating a secure connection.

This approach offers flexibility and ease of assembly, making it a valuable alternative to traditional welding neck flanges.

Delivery

Inspection

Visual Inspection is conducted on fittings to check any surface imperfections. Both fittings body and weld are checked for any visible surface imperfections such as dents, die marks, porosity, undercuts, etc. Acceptance as per applicable standard.

Packing

For packing of carbon steel flanges with painting,we would use the bubble wrap to protect the painting.For flanges without painting or oiled with long-term shipment,we would suggest client to use the anti-tarnish paper and plastic bag to prevent the rust.