Threads in practice – from identification to effective use in pneumatic systems

Threads in practice – from identification to effective use in pneumatic systems

Threads, the foundation of robust pneumatic connections, are essential for reliability and safety. With this guide, you’ll learn how to correctly identify different types of threads and use them in a way that maximizes the performance of pneumatic systems.

Metric, inch and pipe thread basics

Based on the measurement unit, threads are divided into metric, inch and pipe.

Each have their own specific applications and requirements.

Metric threads

Manufactured in accordance with ISO standard, they are widespread around the globe and fundamental to a wide variety of industrial applications. Their versatility, consistency and ease of selection make them indispensable in projects requiring precision and reliability.

The dimensions of metric threads are expressed in millimeters.

Whitworth's inch threads

Also known as imperial, they play a key role in many industries, especially in countries that use the imperial system of measurement, such as the United States, the United Kingdom or Canada. Their unique features and usefulness make them an indispensable component in a variety of technical and engineering applications.

The dimensions of imperial threads are expressed in inches.

Briggs's pipe threads

Specially designed for use in piping systems, they play a key role in many industrial sectors. They are indispensable where tightness and strength of connections are a priority, especially in systems that transfer liquids or gases under pressure.

The dimensions of pipe threads are expressed in inches.

Metric threads - key information

Versatility and ISO standards

Standardized by the International Organization for Standardization (ISO), they are widely used in international industrial cooperation. Their main advantage is their uniformity, which facilitates the exchange of components and tools around the world. This means that metric threads are easily accessible and recognizable, regardless of the country of origin or application.

Characteristics and dimensions

Metric threads are characterized by precise dimensions expressed in millimeters. The outside diameter, thread pitch and thread angle are strictly defined, allowing high accuracy and repeatability in production. This makes them ideal for applications where precision is key, such as in high-end machinery, electronic devices and the automotive industry.

Variety of applications

Because of their standardization and precision, metric threads are used in a wide range of industries. From automotive fasteners to pneumatic and hydraulic systems to advanced electronics and medical equipment. They are especially valued in applications where international compatibility and ease of component interchangeability are required.

Safety and reliability

The use of ISO standard metric threads guarantees not only precision, but also safety. In systems where it is important to withstand high loads or extreme conditions, the accuracy of metric threads ensures the long-term durability of connections. Their consistency and reliability are essential in aerospace and medical equipment, as well as in the construction industry.

Whitworth's inch threads - meaning and application

Importance in industrial applications

Many older machines and systems, especially those made in Anglo-Saxon countries, use this very type of threads. Their presence is still common in machinery, devices and components used in various sectors – from automotive to aerospace.

Basic characteristics

A characteristic feature of Whitworth’s threads is their dimensioning in inches. The thread’s outside diameter, pitch and thread angle are defined in the imperial system, which requires special attention when selecting tools and components. These threads can come in different standards, such as British Standard Whitworth (BSW) or Unified Thread Standard (UTS), each with its own specifications.

Variety of applications

From fasteners in motor vehicles to hydraulic and pneumatic systems to heavy equipment and industrial machinery, the versatility of imperial threads means they continue to be used in many modern structures and projects, despite the growing popularity of the metric system.

Safety and efficiency

Accurate adherence to inch thread standards is critical to ensure the strength of connections, especially in high-demand systems such as aerospace equipment and devices operating in extreme conditions. Improper thread selection can lead to failures and leaks, hence the importance of strict adherence to specifications.

Briggs's pipe threads - where and when to use them

Unique design for tight joints

Pipe threads are distinguished from standard metric or inch threads by their unique design, often with a variable pitch and special profile. They provide a tight and strong connection in pipelines and play a key role in installations where any leakage can lead to system failure, product loss or even safety hazards.

Applications in industrial piping systems

Pipe threads are widely used in industries where fluid or gas throughput is essential. They are often used in the oil and gas industry, in plumbing systems, and even in water supply and heating systems. Their specifications are tailored to the requirements of a system in question, allowing its efficient and safe operation.

Types of pipe threads

Among pipe threads, there are several basic types, such as NPT (National Pipe Tapered) popular in the US, and BSP (British Standard Pipe) used mainly in Europe. Each of these types has its own specific characteristics and is adapted to different standards and requirements.

Safety and standards

Ensuring safety in systems using pipe threads is important, especially in industries where hazardous or high-pressure substances are handled. The use of threads that comply with relevant standards and norms, such as ISO or ASME, is essential to ensure optimal performance and safety.

Thread identification - practical tips

The ability to identify threads is crucial in many technical and engineering fields. Proper identification of thread type is essential to ensure proper part fit and system safety.

The importance of precise measurements

Precision in measurement is extremely important when identifying threads. Even small errors can lead to improper selection, which in turn can result in failures or leaks. Using the right measuring tools is important for accurate results.

Measuring tools

  • Calipers: A versatile tool that allows precise measurement of the outside and inside diameters of threads, as well as their depth. Calipers are essential for identifying most threads.
  • Micrometers: Required to accurately measure small diameters and thread dimensions where precision greater than that of calipers is required.
  • Thread Sights: Allow quick and efficient identification of threads by direct comparison with a standard. Especially useful for identifying the type of thread profile.

Thread identification steps

  • Measuring Diameter: Use a caliper to measure the diameter. For male threads it is the outside diameter, and for female threads – the inside diameter.

  • Determining Thread Pitch: Calculated by applying the caliper to the top of 2 adjacent coils and measuring the distance.

  • Checking the Thread Angle: The thread angle can be measured using specialized tools or gauges.

  • Using a Thread Gauge: A thread gauge allows you to visually compare and identify the type of thread, especially when dealing with different standards.

Thread table - how to use it

A thread table can help identify threads quickly and accurately, as well as support the selection of suitable components.

Practical applications of the thread table in pneumatics include:

  • selection of fittings and components,
  • replacement and repair of parts,
  • design of pneumatic systems.

Among the data in the table, you can find values for parameters such as diameters, pitches, angles and thread profiles. This information is useful in matching correct threads.

  • Diameter: Outer width for male threads and inner width for female threads. The table includes both nominal and actual diameters.
  • Pitch: The distance between the peaks of two adjacent strands of a thread. For metric threads, this distance is measured in millimeters, while for inch threads it is measured in the number of coils per inch.
  • Thread Angle: The angle of the sides of a thread. Different thread systems have different angles.
  • Thread Profile: The shape of the cross-section of a thread. The table can provide information on standard thread profiles, such as metric, inch, pipe and others.

Mistakes in thread selection - how to avoid them

Threads should be matched judiciously to avoid performance drops in pneumatic and mechanical systems or safety hazards.

Common mistakes for improper thread selection include:

  • Improper Matching of a Thread’s Diameter and Pitch:
    A very common mistake. Inconsistency in the diameter and pitch of a matched thread can lead to leaks. To avoid this, always measure the thread accurately with a caliper or micrometer and compare its parameters to agree with the information in the thread table.
  • Confusion of Thread Standards:
    An equally common mistake is confusing metric threads with inch or other standards. These threads have different characteristics and are not interchangeable. Always check and match threads according to the appropriate standards (e.g. ISO for metric, NPT for pipe).
  • Misreading Thread Angle:
    Thread angle is important, especially for metric and inch threads, which have different angles (e.g., 60° for metric and 55° for inch). Using a thread with the wrong angle can lead to a poor fit. Using thread gauges will help you read and match the angle accurately.
  • Ignoring Thread Condition:
    Damaged or worn threads can cause fit problems. It is a good idea to check the condition of the threads before installation to make sure they are clean and undamaged.
  • No Consideration of Operating Conditions:
    Threads can be exposed to a variety of environmental conditions, such as pressure, temperature and chemicals. When choosing a thread, it is important to consider these factors and choose a thread that can withstand the conditions.
  • Neglect of Technical Specifications:
    Always refer to the technical specifications of components to ensure that the chosen thread meets the required criteria. These specifications contain key information about dimensions, tolerances and materials.

Sealing threaded joints

Sealing threaded connections is a key aspect in maintaining the efficiency and safety of various systems – from hydraulic and pneumatic systems to systems that transfer gases and fluids. There are a variety of sealing methods and products, and the choice of the right agent depends on specific operating conditions.

  • Teflon (PTFE) Tapes: One of the most popular solutions in sealing threads. Their main advantage is flexibility and ease of application. Teflon tape acts as a barrier, preventing leaks. It is particularly useful in installations where resistance to high temperatures and chemicals is required.

  • Thread Sealers (Anaerobic): Ideal for permanently sealing threaded connections that do not require frequent disassembly. These chemicals harden in the presence of metal and the absence of oxygen, creating a strong, durable connection. They are effective in systems subject to vibration and temperature fluctuations.

  • Sealing Pastes: Used to provide higher pressure and temperature resistance. They are denser than other sealants, allowing them to fill larger irregularities in threads. The pastes are particularly useful in industrial and automotive installations.

Choosing the right sealant depends on several factors:

  • Type of Medium: Some agents will be suitable for water, other liquids, gases or chemicals.

  • Operating Conditions: Temperature, pressure and the presence of vibration affect the choice of sealant.

  • Removal Frequency: There are sealants that may be more difficult to remove than others, which is important for frequent disassembly.

Disassembly of threaded connections - effective techniques

Disassembling threaded connections can be a challenge, especially when they are old, corroded or very tight.

It is recommended to consider the following tips for safe and effective disassembly:

  1. Joint Condition Assessment:
    The first step should be a thorough assessment of the thread condition. Check for visible damage, corrosion or excess old sealants. The condition of the threads can affect the choice of technique and tools for disassembly.
  2. Use of Penetrating Lubricants:
    For rusty or clogged connections, using penetrating lubricants can make disassembly much easier. Apply the lubricant and wait a few minutes so it has time to penetrate deep into the threads. This can help alleviate corrosion and make it easier to unscrew the connection.
  3. Use of Appropriate Tools:
    The right tools are needed to remove threads. Thread wrenches, adjustable wrenches and, in some cases, torque wrenches, should be sufficient to provide adequate torque without damaging the threads.
  4. “Strike and Unscrew” technique:
    For very tight threads, the “strike and unscrew” technique can be effective. It involves lightly striking the tool (such as a wrench) to ease the tightening. Be careful, however, not to damage the threads.
  5. Heating:
    In extreme cases, gently heating the joint can help loosen it. The heat causes the metal to expand, which can make disassembly easier. However, care must be taken not to damage the components or cause a fire.
  6. Regular Maintenance:
    Regular maintenance and cleaning of threads can prevent future disassembly and assembly problems.

The future of threads in pneumatics

Developments in technology are having a significant impact on the future of threads in pneumatics, opening up new opportunities and development directions, and with them innovative materials and manufacturing techniques affecting the entire pneumatics industry.

  1. New Materials – High Performance Polymers: One of the most important developments in the industry is the introduction of high-performance polymers. These high-tech materials, such as PEEK and fiberglass-reinforced nylon, offer better strength, corrosion resistance and lighter weight compared to traditional metals. In pneumatics, where weight and resistance to various operating conditions are significant, these polymers open up new possibilities, especially in mobile applications and extreme environments.
  2. 3D Printing Technology in Thread Manufacturing: 3D printing is revolutionizing thread manufacturing, enabling the creation of more complex shapes that would be difficult or impossible to produce using traditional methods. This technology enables rapid prototyping and production of custom threads for specific applications. The ability to customize the shape and size of threads without having to create complex molds and tools is a huge step forward.
  3. Sustainability and Ecology: Today’s industry is placing increasing emphasis on sustainability and ecology. New materials and manufacturing technologies are paving the way to create threads that are more environmentally friendly, both in terms of the manufacturing process and recycling at the end of the product’s life.
  4. Personalization and Customization: Technologies such as 3D printing allow for greater personalization and customization of threads to meet specific customer needs. This, in turn, can lead to better fit and performance of pneumatic systems.


Threads are of considerable importance to the pneumatic industry, as they are not only a fundamental part of the connections in pneumatic systems, but also a valuable ingredient affecting their efficiency and safety.

The importance of threads in pneumatics

Threads, being a vital element in costruction of many pneumatic components, play a major role in providing reliability, seal-tightness and durability for systems. The choice, installation and preservation of threads has a serious influence on the functioning of pneumatic devices.

Further learning

We encourage you to further explore the topic of threads and their applications in pneumatics. Understanding their diversity, identification methods and assembly techniques can contribute to a better understanding of the overall operation of pneumatic systems and improve their efficiency, reduce downtime and ensure safety in the working environment.

We hope that this guide has provided valuable information and tips to help you in your work with pneumatic systems.

We thank you for taking the time to read this and encourage you to continue expanding your knowledge of pneumatics. Safe and effective pneumatic systems start with a solid foundation, and threads are one of their most important components.