What are the common standards for push-in brass fitting external thread types

As a key connector in the fields of industrial automation, pneumatic systems, liquid transportation, etc., Push-In Brass Fitting not only focuses on quick installation, sealing performance, and material durability during design, but also must strictly follow various international standard thread specifications to ensure seamless connection with equipment and pipeline systems. The diversity of external thread forms directly determines the adaptability and market coverage of its products.

Metric Thread
Metric thread is an ISO standard thread, widely used in the European and Asian markets, and is one of the most common thread types in the global industrial system.
Features:
The unified pitch marking method is simple, such as M5×0.8, M10×1.0;
The 60° vertex angle is adopted, the thread accuracy is high, and it is suitable for high-precision assembly scenarios;
Commonly used in small pneumatic components, laboratory equipment, and industrial control systems.
Advantages:
Suitable for lightweight equipment and precision instruments;
Highly compatible with European standard equipment;
Supports DIN and ISO standards.

British Standard Pipe (BSP)
BSP thread is a British standard thread, which is divided into parallel (BSPP) and tapered (BSPT) and is widely used in hydraulic, pneumatic systems and pipeline connections.
BSPP (G thread, parallel thread)
Features:
The standard code is G, and the thread is a parallel structure;
The seal usually relies on a sealing gasket or O-ring, and the flatness of the mounting surface is required to be high;
Common specifications include G1/8, G1/4, G3/8, and G1/2.
Application scenarios:
High-precision pipeline connection;
Pneumatic system connectors and pressure regulating valves.
BSPT (R thread, tapered thread)
Features:
The standard code is R, and the thread taper is 1:16;
The seal relies on the interference fit between metal threads and has a self-locking function;
Typical specifications include R1/8, R1/4, R3/8, and R1/2.
Advantages:
Suitable for structures without sealing rings, compact structure;
Firm installation, strong vibration resistance;
Commonly used in pneumatic actuators, oil-gas mixing devices, and gas equipment connection ports.

NPT thread (National Pipe Thread)
NPT is the American standard tapered pipe thread, one of the standards of the American pipeline connection system, suitable for gas and liquid sealing occasions.
Features:
60° thread angle with 1:16 taper;
Self-sealing characteristics, metal surface compression sealing after tightening;
Common specifications include NPT1/8, NPT1/4, NPT3/8, NPT1/2.
Application scenarios:
Petrochemical equipment;
Automation equipment in the North American market;
Pipe joints in hydraulic valve block systems.
Advantages:
Strong pressure resistance after tightening;
PTFE raw tape can be used to improve sealing;
The product has strong adaptability and complies with ANSI/ASME B1.20.1 standards.

UNF thread (Unified Fine Thread)
UNF is a US-made unified fine thread, widely used in places with high requirements for sealing and strength.
Features:
Small pitch, tighter connection;
Commonly used in mechanical systems with high structural requirements and high vibration frequency;
Suitable for pressure sensors and precision pneumatic component connections.
Advantages:
Not easy to loosen after installation;
Common standard for precision equipment;
Perfectly compatible with US-made instrument systems.