Pipe Fittings List: Types, Names, Uses and Classification

1. What Are Pipe Fittings?

Pipe fittings are components used to connect, redirect, branch, reduce, or seal pipelines. The main types include elbows, tees, reducers, couplings, flanges, caps, and valves.

1.1 Main Functions of Pipe Fittings

The most common functions of pipe fittings include:

-  Connection – joining two pipe sections or connecting pipe to valves, pumps, and equipment

-  Direction change – turning flow through 45°, 90°, or custom angles

-  Branching – splitting one line into two or more lines

-  Size transition – connecting different diameters

-  Sealing – closing the end of a pipe or unused outlet

-  Support & fastening – securing the pipe in position

-  Flow control – isolating, regulating, or balancing media flow

1.2 Common Classification Methods

Pipe fittings can be classified in several ways. In industry, the most common methods are:

- By function (elbow, tee, reducer, cap, plug, flange, valve)

- By connection type (threaded, welded, socket weld, grooved, compression, clamp)

- By material (carbon steel, stainless steel, alloy steel, brass, PVC, PE, ABS)

- By standard (ASME, ASTM, MSS, DIN, EN, JIS, BS)

For buyers and engineers, choosing the correct fitting is not only about shape. Pressure rating, wall thickness, corrosion resistance, temperature, connection method, code compliance, and maintenance access all affect the final selection.

2. Pipe Fittings Categories Chart

3. Common Pipe Fittings Names

The table below lists common pipe fittings names and their typical uses. This section is often useful for buyers, new engineers, and users searching for a quick pipe fittings list.

Frequently Used Fittings Explained

Elbow – Used where the pipeline changes direction. Standard types include 45° and 90° elbows.

Tee – Installed at branch points to divide or combine flow paths.

Reducer – Connects different pipe diameters. Available in concentric and eccentric designs.

Flange – A bolted joint used for connecting pipes, valves, and equipment where disassembly may be required.

Union - A union performs a similar connection function to a coupling, but it can be disconnected without rotating the pipe, making maintenance easier.

Cap and Plug - A cap closes the end of a pipe, while a plug is usually used to close an internally threaded outlet or opening.

Valve - Valves are control components in fluid systems. Depending on design, they can isolate flow, regulate pressure, prevent backflow, or divert media.

4. Pipe Fittings Classification by Function

One of the most practical ways to understand pipe fittings is to classify them by what they do in the system. In real projects, engineers usually start with the required function first, then select material, pressure class, and connection type.

4.1 Direction Change Fittings

These fittings are used when the pipeline must turn or avoid structural obstacles.

Common types：Elbow, Bend, Return bend

Typical use: Process lines, building services, skid piping, pump discharge lines, and routing around equipment.

Engineering note: Short-radius fittings save space, while long-radius fittings usually create lower pressure loss and smoother flow.

4.2 Branching Fittings

Branch fittings create one or more outlets from the main pipeline.

Common types: Tee, Reducing tee, Cross, Lateral tee, Branch outlet / Olet fittings

Typical use: Utility distribution systems, instrument take-offs, fire lines, and multi-line process systems.

Engineering note: For higher pressure or larger branch sizes, reinforced branch connections are often preferred over simple fabricated openings.

4.3 Size Change Fittings

These fittings connect pipes of different diameters.

Common types: Concentric reducer, Eccentric reducer, Bushing

Typical use: Pump suction/discharge transitions, flow capacity changes, equipment nozzles, and space-limited piping layouts.

Engineering note: Eccentric reducers are commonly used in horizontal lines where air pockets or drainage issues must be considered.

4.4 Connection Fittings

These fittings are primarily used to join straight pipe sections or create detachable joints.

Common types: Coupling, Union, Flange, Nipple

Typical use: Pipe assembly, maintenance points, valve connections, modular skids, and equipment tie-ins.

Engineering note: Where frequent dismantling is expected, unions or flanged joints are usually more service-friendly than permanent welded joints.

4.5 Sealing and End Closure Fittings

Used to terminate pipe ends or close spare outlets.

Common types: Cap, Plug, Blind flange

Typical use: Future expansion points, hydrotest ends, temporary shutdowns, and permanent dead-end lines.

Engineering note: The sealing method should match system pressure, temperature, and maintenance requirements.

4.6 Control and Protection Components

Although often listed separately from fittings, these components are closely related to piping function.

Common types: Valve, Check valve, Strainer, Expansion joint / compensator

Typical use: Flow isolation, pressure control, backflow prevention, debris protection, and thermal movement compensation.

5. Pipe Fittings by Connection Type

After identifying the function, the next step is selecting how the fitting will connect to the pipe. The correct connection method affects installation speed, leak resistance, maintenance access, and total project cost.

5.1 Welded Pipe Fittings

Welded fittings are permanently joined to the pipe by butt welding or fillet welding.

Common types: Butt weld elbow, Butt weld tee, Reducer, Cap, Socket weld fittings

Typical use: High-pressure systems, high-temperature service, steam lines, oil and gas facilities, and critical process piping.

By ensuring a strong permanent joint and reliable sealing, this solution is specifically designed to withstand demanding service conditions.

Consideration: Requires qualified welding procedures and inspection where codes apply.

5.2 Threaded Pipe Fittings

Threaded fittings use male and female threads for assembly.

Common types: Threaded elbow, Threaded tee, Coupling, Union, Plug, Bushing

Typical use: Small-diameter lines, utility piping, compressed air, water service, and light-duty gas systems.

Designed for efficiency, this method offers fast installation and easy replacement while requiring no hot work.

Consideration: Thread compatibility (such as NPT or BSP) must be confirmed before installation.

5.3 Flanged Connections

Flanged fittings are bolted together with a gasket between mating faces.

Common types: Weld neck flange, Slip-on flange, Blind flange, Lap joint flange

Typical use: Pump stations, valves, equipment nozzles, plants requiring regular maintenance, and larger pipe sizes.

This industrial standard allows for easy disassembly, facilitating convenient inspection and routine equipment servicing.

5.4 Compression and Ferrule Fittings

These fittings seal by tightening a nut that compresses a ferrule or sealing ring onto the tube.

Common types: Compression union, Ferrule connector, Instrument tube fitting

Typical use:

Instrumentation lines, hydraulic systems, gas analyzers, sampling systems, and precision tubing.

Ideal for small tubing systems, this solution provides a clean installation without the need for welding.

5.5 Grooved / Clamp Connections

Grooved systems use a coupling and gasket over grooved pipe ends.

Common types: Grooved coupling, Clamp joint, Mechanical tee

They are widely used in fire protection systems and HVAC piping where speed of installation matters.

Installation is significantly faster than welding, and the connection allows a small amount of flexibility for vibration and movement.

These systems are typically used in medium-pressure applications and are not the first choice for high-pressure or critical process lines.

5.6 Solvent Cement / Fusion Connections

Common in plastic piping systems. The advantage is simple: lightweight, corrosion-resistant, and relatively low installation cost.

Examples: PVC solvent-weld fittings, PPR hot fusion fittings, PE butt fusion fittings, Electrofusion fittings

Typical use: Water supply, drainage, chemical lines, irrigation, and lightweight utility systems.

6. Pipe Fittings by Material

Material selection affects corrosion resistance, pressure rating, fabrication method, and service life. The table below shows the most common fitting materials and where they are typically used.

Practical Rule

- Corrosive media → check compatibility first

- High pressure / temperature → check material strength first

- Routine service → compare total installed cost

7. Gas Pipe Fittings Names and Uses

Gas pipe fittings are used to connect, control, branch, or terminate fuel gas lines safely. Compared with ordinary water piping, gas systems place higher importance on leak-tight threads, approved materials, and correct shutoff access.

Common Gas Pipe Fittings List

8. Pipe Fittings Standards and Sizes

Pipe fittings are defined by standards as much as by shape. In real projects, compatibility is what determines whether components actually fit together on site.

ASME, DIN, and JIS systems are not interchangeable. Even when nominal sizes match, differences in bolt patterns, sealing faces, and tolerances can prevent proper assembly. This becomes especially visible in multi-supplier projects.

NPS and DN are commonly treated as equivalent size systems, but they are only approximate conversions. Misalignment rarely appears on paper — it usually shows up during installation.

Pressure class and schedule must also align across pipes and fittings. A correct size with an incorrect rating will still create a weak point in the system.

For procurement, a complete specification always includes standard, size, pressure rating (or schedule), and material grade. Anything less increases the risk of substitution errors.

9. FAQs

Q1: What is the most common pipe fitting?

Elbows and tees are the most widely used, as most piping systems require direction changes and branch connections.

Q2: Can NPT and BSP fittings be used together?

No. They have different thread forms and sealing methods. Mixing them can cause leakage.

Q3: Are threaded fittings suitable for gas lines?

They are used in low-pressure gas systems, but proper sealing and thread compatibility are critical.

Q4: What causes most fitting installation problems?

In practice, incorrect standards, mismatched sizes, or wrong pressure ratings are more common causes than fitting type selection.

Q5: What are the 7 main types of pipe fittings?

A: The most common pipe fittings include elbow, tee, reducer, coupling, union, flange, and cap. These fittings cover direction change, branching, connection, and sealing functions in most piping systems.

Q6: How do I choose the right pipe fittings for my project?

A: Selecting pipe fittings depends on pressure rating, temperature, material compatibility, connection type, and application (such as gas, water, or industrial use). It is also important to match standards like ASME or DIN to ensure compatibility.

10. Explore Pipe Fittings Guides

To help you better understand different types of pipe fittings and their practical applications, you can explore the following detailed guides:

(1) What is a Seamless Elbow?

- Learn the basic definition, structure, and applications of seamless elbows in piping systems.

(2) Seamless Elbow Forming Methods

- Understand how seamless elbows are manufactured, including hot forming and cold forming processes.

(3) Advantages of Seamless Elbows

- Discover why seamless elbows are widely used in high-pressure and critical piping systems.

(4) What is a Pipe Flange?

- A complete guide to flange types, functions, and where they are used in piping systems.

(5) Pipe Reducer Types and Applications

- Learn the differences between concentric and eccentric reducers and how to choose the right one.