ASME B16.11 Forged Fittings for Piping Reviewed - Projectmaterials

FORGED FITTINGS ASME B16.11

WHAT ARE FORGED FITTINGS?

ASME B16.11 is a standard that specifies the dimensions, tolerances, ratings, and material requirements for forged fittings, both socket-welding and threaded, used in piping systems.

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These fittings are designed for use in areas involving high pressure, temperatures, and potentially corrosive conditions. Forged fittings are made through a process that involves shaping metal under high pressure, usually at room temperature, which enhances their strength, fatigue resistance, and durability compared to cast fittings.

SOCKET/THREADED FITTINGS in ASME B16.11

1. Socket-Weld Fittings: These fittings are connected to pipes by inserting the pipe into the recess of the fitting (the “socket”) and then applying fillet weld around the top. This method provides a strong, leak-proof connection suitable for high-pressure applications. Common socket-weld fittings include elbows, tees, couplings, and caps.

2. Threaded Fittings: These fittings are connected to pipes via threads. Threaded fittings are easier to install and remove than socket-weld fittings but are typically used in lower-pressure applications. Common threaded fittings include elbows, tees, couplings, and bushings.

Common Materials for ASME B16.11 Forged Fittings

• Carbon Steel: Widely used due to its strength and versatility in varying temperatures and pressures.
• Stainless Steel: Offers excellent resistance to corrosion and oxidation, making it suitable for corrosive environments.
• Alloy Steel: Used for applications requiring higher strength and resistance to wear and tear.
• Duplex and Super Duplex Stainless Steel: Provide higher strength and corrosion resistance, suitable for harsh environments.
• Nickel Alloys: Ideal for extreme temperature and corrosive applications.

Sizes and Pressure Ratings

• ASME B16.11 covers fittings in sizes from 1/8 inch to 4 inches (NPS).
• The pressure ratings (“Class”) vary based on the type of fitting and the material, generally ranging from Class , Class , to Class for high-pressure applications.

Applications of ASME B16.11 Forged Fittings

• Oil and Gas: Used in both upstream extraction and downstream processing where high pressure and corrosive conditions are common.
• Chemical Processing: Forged fittings are used to handle various chemicals and solvents, requiring resistance to corrosion and high pressures.
• Power Generation: In power plants, especially in systems involving steam, where temperature and pressure conditions are high.
• Manufacturing and Industrial: Forged fittings are used in machinery, equipment, and processes that involve high pressures and temperatures.

ASME B16.11 forged fittings are crucial components in ensuring the integrity and safety of piping systems under high-stress conditions. Their durability and resistance to high pressure and temperatures make them an essential choice for critical applications across various industries.

What does “Class” mean for Forged Fitting?

The “class” of a forged fitting in piping systems refers to the pressure rating of the fitting, indicating the maximum pressure that the fitting can withstand at a specified temperature. This classification system helps ensure the safe operation of piping systems by matching the pressure capabilities of all components to the system’s requirements.

Understanding Pressure Classes

Pressure classes for forged fittings are defined by several standards organizations, including the American Society of Mechanical Engineers (ASME) and the Manufacturers Standardization Society (MSS). The class designation is a numerical value that typically ranges from , , , to for forged steel fittings, with each number roughly correlating to the maximum pressure (in pounds per square inch, psi) that the fitting can handle at room temperature. For example:

• Class : Suitable for systems operating at up to psi.
• Class : Suitable for systems operating at up to psi.
• Class : Suitable for systems operating at up to psi.
• Class : Suitable for systems operating at up to psi.

It’s important to note that the actual maximum pressure rating can vary based on the material of the fitting and the operating temperature of the system. ASME B16.11, for example, provides detailed tables that specify the maximum allowable pressure for different materials and temperature ranges.

Material Considerations

The class of a forged fitting not only indicates its pressure rating but also implies certain material qualities. For example, higher-class fittings, capable of withstanding greater pressures, are typically made from materials with higher strength and durability.

Application

Selecting the correct class of forged fitting is critical for ensuring the integrity and safety of a piping system. The choice of class should be based on:

• The maximum operating pressure of the system.
• The temperature conditions under which the system will operate.
• The compatibility of the fitting material with the fluid being transported.

In summary, the class of a forged fitting is a critical specification that determines its suitability for use in a particular pressure environment, contributing to the overall safety and reliability of piping systems in various industrial applications.

Forged vs. Buttweld Fittings

The main differences between forged and buttweld fittings relate to piping system sizes (smaller for forged, larger for BW), applicable ASME specifications, and manufacturing process/raw materials.

Piping system bore size

Forged fittings are used for piping systems below 2 or 4 inches in diameter (4″ for #/# fittings, 2″ for  #/# fittings), whereas buttweld fittings are used for larger diameter piping.

ASME specifications

The ASME B16.11, MSS SP 75, MSS SP 83, and MSS SP 95 specifications cover forged fittings (socket weld and threaded) to fit ASME B36.10 and ASME B36.19 carbon, alloy, stainless steel, and nickel alloy pipes of small bore size.

Raw materials/manufacturing process

Forged fittings are manufactured from solid blocks of steel, that are machined to obtain the final required shape within the tolerances set by the applicable specifications mentioned above. This is different from buttweld fittings, which are manufactured by cutting, bending, and shaping seamless or welded steel pipes.

Applicable Specifications (ASME/MSS)

The American Society of Mechanical Engineers (ASME), Manufacturers Standardization Society (MSS), and the American Petroleum Institute (API) provide specifications for forged fittings used in piping systems. These specifications define the standards for the design, dimensions, material, and testing of forged fittings to ensure reliability, safety, and interoperability in various industrial applications. Here’s an overview of key specifications from ASME, MSS, and API for forged fittings:

ASME Specifications

ASME B16.11: This standard covers forged steel fittings, including socket welding and threaded types. It specifies dimensions, tolerances, marking, and material requirements for fittings in sizes NPS 1/8 through NPS 4 and pressure ratings from Class to Class . Common materials include carbon steel, stainless steel, and alloy steel.

MSS Specifications

• MSS SP-79: This standard specifies requirements for insert-type socket-welding fittings made from bar stock for sizes NPS 1/2 through NPS 4.
• MSS SP-83: Covers the design and dimensions of class and class threaded and socket-welding steel pipe unions.
• MSS SP-97: Provides standards for integrally reinforced forged branch outlet fittings (such as Weldolets, Threadolets, and Sockolets) for butt-weld, socket welding, and threaded connections.

API Specifications

• API 602: This specification covers compact steel gate valves, globe valves, and check valves in sizes DN 4 (NPS 1/8) through DN 100 (NPS 4) for use in refinery and petrochemical service.
• API 6D: Although primarily for pipeline valves, API 6D can be relevant for forged fittings used in conjunction with pipeline valves in the oil and gas industry.

Considerations for Selecting Forged Fittings

• Material Compatibility: The selection of material for forged fittings should match or exceed the performance requirements of the piping system, taking into account factors such as temperature, pressure, and corrosion resistance.
• Pressure Ratings: Fittings must be chosen based on the pressure rating required for the application, ensuring they can withstand the system’s maximum operating pressure.
• Industry and Application: The choice between ASME, MSS, or API specifications may depend on the specific industry (e.g., oil and gas, chemical processing, power generation) and the application requirements, including regulatory compliance.

These specifications are crucial for ensuring the quality and safety of forged fittings used in piping systems. They provide a framework for manufacturers, engineers, and end-users to specify and utilize fittings that meet the necessary standards for performance, reliability, and safety in various industrial applications.

TYPES OF FORGED FITTINGS

Forged fittings can be classified by connection type and shape:

• connection type: in this case, the key dichotomy is between socket weld and threaded fittings
• fitting shape: this classification is based on the body shape of the fitting (elbows, tees, caps, adapters, couplings, etc)

SOCKET WELD VS. THREADED FITTINGS TYPES

The difference between socket-weld and threaded fittings is the first concept to grasp when discussing the available types of forged fittings. These two types, mentioned in the ASME B16.11 specification, differ in the way the fitting is connected to the piping system. The two types (SW, and THD) are shown in the image below:

SOCKET WELD FITTINGS (“SW”)

FORGED FITTINGS BY SHAPE

This section of the article covers the types of forged fittings based on their body shape.

Forged Elbow 45/90 Degrees

Forged elbows are pipe fittings that facilitate directional changes in piping systems, allowing fluids to change direction at either a 45-degree or a 90-degree angle. They are manufactured through the forging process, which involves shaping metal under high pressure and temperature, resulting in a fitting with superior strength, durability, and resistance to impact, fatigue, and thermal fluctuations compared to cast fittings.

Forged elbows are used in high-pressure applications and in environments requiring solid performance. Forged elbows are manufactured according to ASME B16.11 in various material grades, either with socket weld or threaded pipe connections. The 3 main types of forged elbows are:

• 45-Degree Elbows: Used to redirect the piping system at a 45-degree angle. They are typically employed where a full 90-degree turn is unnecessary, allowing for a more gradual change in direction which minimizes pressure drops and flow resistance.

• 90-Degree Elbows: Used to make a quarter turn in the piping, changing the direction of the flow by 90 degrees. This type of elbow is common in piping systems that need to route pipes in different directions or around obstacles.

• Street-Elbow: A street elbow is a type of forged fitting that allows for a change in direction in the piping system. It differs from standard elbows in its configuration; one end of a street elbow is male (external threads), and the other end is female (internal threads). This design enables the street elbow to connect directly to another fitting without requiring a pipe nipple or additional length of pipe between them, making it particularly useful in tight spaces or when minimal piping is desired.

Forged Tee (Equal/Reducing)

Forged tees are pipe fittings used to either combine or split the flow of a fluid. They are essential components in piping systems, allowing for directional change and branching off. Forged tees are made through a forging process, which involves shaping metal under high pressure and heat, resulting in a piece that’s exceptionally strong and durable. There are two main types of forged tees: equal tees and reducing tees, each serving different purposes based on the requirements of the piping system.

Forged tees ASME B16.11 are available with socket weld or threaded connections (NPT or BSP). The dimensions of forged tees are covered by the MSS SP 75 and the ASME B16.11 specifications.

Forged Lateral

A forged lateral fitting is a type of pipe fitting used to branch off from the main line in a piping system at an angle other than 90 degrees, typically at a 45-degree angle (or 30 degrees). It is called “lateral” because it allows for a lateral (side) connection, facilitating a branch line to divert from the main flow path (Y-shape). These fittings are made through the forging process, where metal is heated and then shaped under high pressure, resulting in a very strong and durable fitting.

Forged Plug (Round, Squared, Hex)

Forged plugs are components used to close off (blind) the ends of piping, valves, or fittings, providing a sealed closure. They are commonly used in various industrial applications to temporarily or permanently stop the flow within a pipeline. Forged plugs are manufactured through the forging process, which involves shaping metal under high pressure and heat, resulting in a highly durable and robust component. These plugs come in various shapes, including round, squared, and hexagonal (hex), each serving specific installation and operational needs.

Bushings

A forged bushing is a type of pipe fitting used to connect two pipes of different diameters, acting as a reducer to facilitate the transition between sizes in a piping system. Unlike couplings, which generally connect pipes of the same diameter, bushings are designed to fit inside a larger fitting, valve, or pipe and accommodate a smaller pipe on the other side. They are manufactured through the forging process, where metal is heated and then shaped under high pressure, enhancing the fitting’s strength, durability, and resistance to wear and pressure.

Couplings (Half, Full)

A forged coupling is a type of pipe fitting that allows two pipes to be joined together. It is manufactured through the forging process, where metal is heated and then formed into the desired shape under high pressure. This manufacturing technique enhances the coupling’s strength, making it suitable for high-pressure, high-temperature, and harsh environmental conditions. Forged couplings are used extensively in various industrial piping systems to create a seamless and secure connection between pipe sections.

Forged couplings are available in different shapes:

1. Full Coupling: Designed to connect two pipes of the same diameter. A full coupling has a socket or threaded end on both sides, allowing it to join two pipes directly.

2. Half Coupling: Features a socket or threaded end on one side only. It is welded to the end or side of a pipe or tank, providing a connection point for another pipe.

3. Reducing Coupling: Used to connect two pipes of different diameters. A reducing coupling has differing diameters on each end, accommodating the sizes of the pipes being connected.

Reducers and Reducer Inserts

Forged reducers and reducer inserts are types of fittings used in piping systems to connect pipes of different diameters, facilitating a smooth transition between sizes. These components are crucial for managing flow rates, accommodating system design variations, and integrating equipment with differing connection sizes.

Both are manufactured through the forging process, where metal is heated and then shaped under high pressure to enhance strength, durability, and resistance to wear and environmental factors.

Forged Reducers

Forged reducers come in two primary types, each serving a specific purpose in piping systems:

1. Concentric Reducers: These have a conical shape, with both the inlet and outlet being aligned along the same central axis. Concentric reducers are used when the pipes to be connected are on the same plane. They are ideal for fluid flow applications where there’s a need to avoid trapping air or sediment within the piping system.

2. Eccentric Reducers: Eccentric reducers have one off-center side, meaning the pipes are aligned on one side only. This design is used to maintain the same top or bottom pipe level, preventing the accumulation of air or sediment in the system. Eccentric reducers are particularly useful in horizontal piping systems.

Reducer Inserts

Reducer inserts are a specialized type of fitting used to reduce the size of a socket weld connection without the need for extensive reconfiguration or the use of multiple fittings. They are inserted into the larger socket of a coupling, valve, or fitting to accommodate the smaller-sized pipe. Reducer inserts are an economical and space-saving solution for size reduction in socket welding applications.

The American Society of Mechanical Engineers (ASME) B16.11 standard, which covers forged fittings, socket-welding, and threaded, categorizes reducer inserts into two types: Type 1 and Type 2. Understanding the differences between these two types is crucial for selecting the appropriate fitting for a given application.

Reducer Insert Type 1

Type 1 reducer inserts are designed to fit into the larger socket of a fitting, valve, or flange to reduce its effective internal diameter to accommodate a smaller size pipe. The key characteristics of Type 1 reducer inserts include:

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• Configuration: The outer diameter of a Type 1 insert matches the inner diameter of the socket, while the inner diameter provides a snug fit for the smaller pipe size.
• Application: They are typically used where the flow direction is from the larger to the smaller size, ensuring a smooth transition that minimizes turbulence and pressure drop.
• Installation: Type 1 inserts are inserted directly into the socket before welding, and they require careful alignment to ensure a proper seal and to maintain flow efficiency.

Reducer Insert Type 2

Type 2 reducer inserts differ from Type 1 primarily in their installation orientation and are used in specific applications where the flow direction or assembly requirements dictate their use. Characteristics include:

• Configuration: Similar to Type 1, the outer diameter of a Type 2 insert matches the inner diameter of the fitting’s socket. However, the design may differ slightly to accommodate reverse flow conditions or specific installation requirements.
• Application: Type 2 inserts can be used in situations where the flow is from the smaller to the larger size, or where Type 1 inserts are not suitable due to design constraints.
• Installation: The installation process for Type 2 inserts is similar to that of Type 1, with an emphasis on ensuring that the insert is properly aligned within the socket for welding.

Union

A forged union is a type of pipe fitting used to connect two pieces of pipe in a piping system, while also allowing for easy disconnection and reconnection without the need for cutting or welding. Unlike couplings, which are used to create a permanent joint between two pipes, unions are designed for situations where piping components may need to be removed or replaced, or where routine maintenance is expected.

The forging process used to manufacture these fittings involves shaping metal under high pressure and heat, resulting in a component with superior strength, durability, and resistance to wear and pressure compared to cast fittings.

Structure of a Forged Union

A typical forged union consists of three parts:

1. Male End: A threaded end that connects to one piece of pipe.
2. Female End: A threaded counterpart that connects to another piece of pipe.
3. Nut: A central component that fits over the male end and screws onto the female end, pulling the two ends together to make a secure connection.

Unions are also available in the male-to-female, female-to-female types, lug-nut, and Rockwood designs. Unions comply with the MSS SP 83 standard.

Welding Boss

A forged welding boss is a type of pipe fitting used to provide a take-off point from the main pipeline, allowing for the connection of auxiliary equipment or the installation of instrumentation, such as pressure gauges or thermowell.

It is called a “boss” because it serves as a mounting point or a reinforced area where additional components can be attached to the piping system. The term “forged” refers to the manufacturing process used to create the boss, where metal is shaped under high pressure and temperature to produce a fitting with superior strength, durability, and resistance to impact and fatigue.

Characteristics of a Forged Welding Boss:

• High Integrity: The forging process enhances the metallurgical properties of the material, resulting in a component that can withstand high pressures, high temperatures, and harsh environments.
• Versatility: Forged welding bosses can be used in a variety of piping materials and designs, accommodating different pipe sizes and schedules.
• Connection Points: They typically have one or more threaded outlets for the attachment of devices or for branching off to smaller pipes.
• Installation: The boss is welded onto the pipe where the connection or attachment is needed. The welding process ensures a strong, leak-proof joint between the boss and the pipe.

Swage Nipple

A swage nipple is a versatile and essential piping component commonly used in the oil and gas, construction, and power generation industries to facilitate the connection between pipes of different diameters.

It serves as a reducer to transition smoothly between pipes of varying sizes, ensuring a reliable and efficient flow path in a piping system. This educational overview will delve into the definition, types, manufacturing processes, design considerations, and applications of swage nipples, shedding light on their importance and utility in various industrial applications.

Definition

A swage nipple, also known as a swage reducer, is a type of fitting used to join two pipes of different diameters, providing a gradual transition that minimizes turbulence and pressure drop in the system. It is typically conical in shape, with one end matching the outer diameter of the larger pipe and the other end the smaller pipe, facilitating a seamless flow transition.

Types

Swage nipples are categorized based on their end connections and manufacturing processes:

• Concentric Swage Nipple: Features a uniform conical shape, tapering evenly from the larger to the smaller diameter. It is used where the center lines of the pipes are in alignment, minimizing disruption to flow.

• Eccentric Swage Nipple: Has an off-center taper, allowing for the connection of pipes with different diameters without misaligning the bottom of the pipe. This is particularly useful in applications where maintaining a flat bottom is necessary for drainage or flow.

Manufacturing Processes

Swage nipples are manufactured primarily through forging or machining processes:

• Forging: Involves shaping the metal under high pressure, usually while it’s hot. Forged swage nipples have enhanced strength and are preferred for high-pressure applications.

• Machining: The swage nipple is shaped from a solid bar or pipe using lathes or CNC machines. This method provides precision and is used for specific dimensions and materials.

Design Considerations

When selecting a swage nipple for a piping system, several design considerations should be taken into account:

• Material Compatibility: The material of the swage nipple must be compatible with the pipes it connects and the fluid it carries, considering factors like corrosion resistance, temperature, and pressure.

• Pressure Rating: Ensure the swage nipple meets the required pressure rating for the application, taking into account the potential for pressure drops across the reducer.

• End Connection Type: Choose between threaded or plain/beveled ends based on the connection method (welded or screwed) used in the piping system.

Applications

Swage nipples are used across a wide range of industries due to their functionality and adaptability:

• Oil and Gas Industry: Utilized for pipelines and processing equipment to connect pipes of different diameters, facilitating the transport of oil, gas, and processed fluids.

• Power Generation: Employed in steam, water, and gas lines within power plants to ensure efficient and controlled flow across systems of varying diameters.

• Construction: Used in plumbing and HVAC systems of buildings to adapt piping networks to the required sizes, ensuring effective distribution of water, air, and gas.

In summary, swage nipples play a critical role in the seamless and efficient transition between pipes of different diameters within industrial piping systems. Their design and selection are pivotal in minimizing flow disturbances, maintaining pressure integrity, and ensuring the overall reliability and performance of the piping network. Understanding their types, manufacturing processes, and design considerations is essential for engineers and technicians to optimize piping designs and operations in their respective fields.

Piping systems are a vital part of modern industries, ensuring the seamless transport of liquids, gases, and other materials. These systems are centred on MS Forged Fittings that provide the required stability for optimum operation. These components are made from mild steel; they are able to perform well under high working pressure.

This blog will explore the various types of MS Forged Fittings, their unique characteristics, and the industries where they are most commonly used.

What Are MS Forged Fittings?

MS Forged Fittings are essential connectors crafted by forging mild steel under extreme pressure and temperature. The forging process reduces some internal flaws in the metal hence producing fittings with improved mechanical properties such as tensile strength and impact strength.

These fittings come in various shapes, sizes, and pressure classes designed to fit specific industrial requirements. Whether it’s redirecting the flow, branching pipelines, or sealing ends, MS Forged Fittings ensure reliable and leak-free connections.

Comprehensive List of MS Forged Fittings

Elbows

MS Elbows are indispensable for changing the direction of fluid flow in pipelines.

• Key Features: Available in 45°, 90°, and 180° angles, with long or short radii.
• Applications: Used in water treatment plants, power plants, oil refineries, and residential plumbing.

Tees

MS Tees enable the flow of fluids to branch into multiple directions.

• Key Features: Available as equal or reducing tees, depending on pipeline diameters.
• Applications: Commonly seen in HVAC systems, irrigation pipelines, and chemical industries.

Couplings

MS Couplings join two pipes to create a seamless flow.

• Key Features: Available as full or half couplings, based on application needs.
• Applications: Widely used in plumbing, gas distribution, and industrial repair tasks.

Unions

MS Unions are designed for ease of disassembly without cutting the pipeline.

• Key Features: Typically made of three parts for quick installation and removal.
• Applications: Found in pipelines requiring frequent maintenance, such as in food processing or pharmaceutical industries.

Caps

MS Caps are used to seal the end of pipelines.

• Key Features: Designed for easy removal and reinstallation.
• Applications: Essential during pressure testing, cleaning, or temporary sealing of pipelines.

Reducers

MS Reducers connect pipes of different diameters to regulate flow and pressure.

• Key Features: Available as concentric or eccentric reducers.
• Applications: Used in industries like petrochemical, construction, and energy generation.

Nipples

MS Nipples are short pipe sections with threads on both ends used to connect fittings.

• Key Features: Straight, hexagonal, or tapered designs available.
• Applications: Seen in compressed air systems, hydraulic lines, and gas supply pipelines.

Bushings

MS Bushings serve to connect fittings of different sizes by reducing the opening diameter.

• Key Features: Compact and easy to install.
• Applications: Used in industrial gas pipelines, steam lines, and chemical processing plants.

Crosses

MS Cross fittings split or combine the flow from four directions.

• Key Features: Manufactured to handle high-pressure environments.
• Applications: Common in fire-fighting systems and irrigation setups.

Why Choose MS Forged Fittings?

MS Forged Fittings offer numerous advantages, making them a popular choice in industries:

1. Durability and Strength: These fittings are made through high pressure, therefore, they possess a strong construction that can withstand high pressure and heat.
2. Cost-Effective Solution:  Mild steel is cheaper than other materials, and thus appropriate for use in large structures.
3. Versatility: They are compatible with various piping materials like carbon steel, stainless steel, and PVC.
4. Corrosion Resistance: When coated or galvanized, MS Forged Fittings resist rust and chemical damage, extending their lifespan.
5. Ease of Installation: These fittings are designed for simple installation, reducing labour time and costs.

Industries Utilizing MS Forged Fittings

MS Forged Fittings are employed in a wide range of industries due to their versatility and dependability.

• Oil & Gas Industry: Ensuring leak-proof connections for transporting oil and natural gas.
• Chemical Processing Plants: Handling corrosive substances under high pressure and temperature.
• Construction Sector: Used in structural frameworks, HVAC systems, and plumbing lines.
• Power Generation: Vital for steam pipelines in thermal and nuclear power plants.
• Water Treatment Plants: Ensuring efficient water distribution and wastewater management.
• Automotive Industry: Used in hydraulic systems and vehicle fuel pipelines.

How to Select the Right MS Forged Fittings

Choosing the right MS Forged Fittings is crucial for the safety and efficiency of your piping system. Here are some factors to consider:

1. Material Grade: Ensure the fittings meet the required standards for your application.
2. Pressure Rating: Select fittings that can handle the maximum operating pressure.
3. Size and Compatibility: Ensure the fittings match the pipeline diameter and material.
4. Coatings: Opt for coated fittings if the system is exposed to corrosive substances or environments.
5. Certification: Always source from reliable manufacturers who provide quality certifications and guarantees.

Conclusion

MS Forged Fittings are used in piping systems in various industries as they are one of the strongest and durable, and cost-effective. Each fitting type has its own role, starting from elbow, cap, reducer and so on, to enable the pipeline to run smoothly and safely.

When investing in MS Forged Fittings, always prioritise quality and compatibility to achieve the best results. A trusted supplier can provide a wide range of options tailored to your requirements, ensuring long-term performance and reliability.

If you’re in search of premium MS Forged Fittings, reach out to industry experts to get the right products for your needs.

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