Carbon Steel Pipe Fittings

Carbon steel pipe fittings are belonged to ASME B16.9 & ASME B16.11 standard specifications that covers buttweld pipe fittings, forged socket weld fittings and threaded pipe fittings. These fittings provide best flow characteristics and reduce frictional resistance and pressure loss. Carbon steel fittings are used to manufacture, process and transport liquids, gases, chemicals and other fluids, especially in large piping systems, such as oil and gas industry, midstream, shipbuilding, power plants, food factories, pharmaceutical factories, etc.

ASTM A234 WPB carbon steel seamless pipe fittings are made by ASTM A106B & API 5L B seamless steel pipes, while welded fittings are fabricated by ASTM A53B welded pipes.

Types of Carbon Steel

• Low-carbon steel: the most widely used form of carbon steel, with a carbon content of less than 0.25% - they are usually relatively weaker and softer but more easily welded and ductile, and so they are often used to machine and weld for a low cost.

• Medium-carbon steel: with a carbon content of 0.25-0.6%, and a manganese content of 0.6-1.65%, these metals can be improved via heat treatment, though this can only be performed on very thin sections unless additional alloying elements are added – these steels are stronger but less ductile than lower-carbon steels.

• High-carbon steel: this is the hardest and toughest carbon steel, with the lowest ductility, very wear-resistant and almost always hardened and tempered – they tend to have a carbon content from 0.6-1.25% and a manganese of 0.3-0.9%.

What is ASME B16.9 Buttweld Pipe Fittings

Buttweld pipe fittings materials are available in carbon steel, alloy steel and stainless steel. They are an important part in industrial piping system to change direction, branch off or to mechanically join equipment to the system. The dimensions and tolerances are defined as per ASME B16.9. There are some types that Elbow, Bend, Tee, Reducer, Cap and Stub End.

Carbon Steel Buttwelding Fittings Specification

Tolerance 

Advantages

1. Welded connection offers more robust connection.

2. Continuous metal structure adds to the strength of the piping system.

3. Matching with pipe schedules, offers seamless flow inside the pipe. 

4. Full penetration weld offers gradual transition via welded pipe fitting.

What is ASME B16.11 Socket Weld Fittings 

ASME B16.11 Socket weld fittings are used to permanently connect pipes that are inserted into fittings, flanges or valve. After proper inserted, the pipe shall be connected to the fitting with fillet seal welds. They can be used to change the direction of pipe networks and connect pipes at different angles and small diameters. Its high leakage integrity and structural strength make it suitable for various pipe network applications.

Carbon steel ASTM A105 socket weld fittings are machined from A105 round or square bars. It is including the socket weld elbow, tee, coupling, union, cap, reducing insert and sockolet.

Carbon Steel Socket Weld Fitting Specification

Tolerance for ASME B16.11 Socket Weld Fittings

Advantages 

1. The socket enables proper alignment easily.

2. Lower risk of leakage than threaded fittings.

3. Cheaper to install than butt weld fittings.

4. The socket design that weld metal does not flow into the pipe bore.

What is ASME B16.11 Threaded Pipe Fittings 

Threaded Connections are widely used for small bore piping having nominal diameters NPS 2 or smaller, but also available up to NPS 4 sometimes. This is the oldest pipe joining method but still highly popular. Threaded pipe fittings are used for non-critical applications with lower temperatures and pressure services. The majority of threaded fittings are used in the plumbing industry. 

Carbon steel ASTM A105 socket weld fittings are machined from A105 round or square bars. It is including forged threaded elbow, tee, coupling, union, cap, plug and bushing, nipple and threadolet.

Carbon Steel Threaded Pipe Fittings Specification

Tolerance for ASME B16.11 Threaded Fittings

Advantages

1. Quick installation.

2. Installation is easy.

3. Parts can be detached.

4. Economic and cheaper.

5. Leakage integrity is good.

6. Less force is required for joining.

Standards for Thread Connections

• ASME B16.11: Forged Fittings, Socket Welding and Threaded.

• MSS-SP-83: Class 3000 Steel Pipe Unions, Socket-Welding and Threaded

• ASME B16.3: Malleable Iron Threaded Fittings

• ASME B16.4: Gray Iron Threaded Fittings

• ASME B16.39: Malleable Iron Threaded Pipe Unions

• ASME B16.34: Valves — Flanged, Threaded, and Welding End

• ASME B16.39: Malleable Iron Threaded Pipe Unions, Class 150, 250, and 300