What is G thread?
In the fields of mechanical manufacturing and engineering, threads are a common connection method, and G threads, as one of the important types, are widely used in pipe connection and sealing situations. This article will introduce in detail the definition, characteristics, application scenarios and comparison of G threads with other threads to help readers fully understand this technical detail.
1. Definition of G thread
G thread, full name"Pipe Thread"(G stands for "Gas" or "G Pipe"), which is a tapered pipe thread based on imperial units and is mainly used for pipe connections of gas or liquid. Its standards are based on ISO 228-1 (unsealed pipe threads) and ISO 7-1 (sealed pipe threads). The G thread is characterized by a 55-degree profile angle, and the top and bottom of the thread are rounded to improve sealing performance.
2. Classification of G thread
| Type | Standard | Features | Application scenarios |
|---|---|---|---|
| G (unsealed pipe thread) | ISO 228-1 | No sealing requirements, need to be used with sealing materials | Low pressure water pipes and gas pipelines |
| R (sealing pipe thread) | ISO 7-1 | With built-in sealing capability, the thread taper is 1:16 | High-pressure oil pipes and gas pipelines |
3. Specifications of G thread
The specifications of G thread are usually expressed as "G+ size", such as G1/2, G3/4, etc. The following are the dimensional parameters of common G threads:
| Thread code | Nominal diameter (inches) | Thread pitch (mm) | teeth per inch |
|---|---|---|---|
| G1/8 | 1/8 | 0.907 | 28 |
| G1/4 | 1/4 | 1.337 | 19 |
| G1/2 | 1/2 | 1.814 | 14 |
| G3/4 | 3/4 | 1.814 | 14 |
4. Comparison between G thread and other threads
G thread is often confused with NPT (American Standard Taper Pipe Thread), BSPT (British Standard Taper Pipe Thread), etc. The following are their differences:
| Thread type | tooth angle | taper | Sealing method |
|---|---|---|---|
| G thread (BSPP) | 55° | No taper | Requires gasket or raw material tape |
| BSPT (R thread) | 55° | 1:16 | Thread self-sealing |
| NPT | 60° | 1:16 | Thread self-sealing |
5. Precautions for application of G thread
1.Sealing: The G thread itself has no sealing function and needs to be used with raw material tape or sealant;
2.size match: When installing, ensure that the internal and external thread specifications are consistent to avoid misaligned threads;
3.Tightening force: Over-tightening may cause thread deformation and affect sealing;
4.Material selection: It is recommended to use corrosion-resistant materials such as brass and stainless steel.
6. Hot topics related to the entire network
Recent hot discussions about G threads focus on the following areas:
-New energy pipeline system: Improvement of sealing technology for G threads in hydrogen energy pipelines;
-Smart home installation: Standardized connection issues for household water purifier pipes;
-Industry 4.0 applications: Design innovation for quick disassembly and assembly threads in automation equipment.
Summary
As one of the basic standards for pipe connections, G thread occupies an important position in low-pressure fluid systems due to its simplicity and reliability. With the advancement of material technology and sealing technology, higher-performance derivative models may appear in the future, but at this stage, mastering the standardized use of G threads is still an essential skill for engineers and technicians.
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