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Introduction
In the use of pipe fittings, the thread types are very important to keep the safety and leak proof connection. There are many different kinds of thread types. BSP thread (British Standard Pipe) and G thread are commonly used widely and can be converted, especially in the area of pipeline and industrial applications. In this paper, we will deeply discuss the different usages between BSP and G thread, and how to recognize and choose proper thread type.
BSP thread (British Standard Pipe) and G thread many correspondences, but they are not totally the same. Because of the similarities, BSP thread (British Standard Pipe) and G are often confused. BSP is a thread type of creating fittings, there are two main variants: BSPP (parallel) and BSPP (tapered). G thread is a parallel version of BSP, similar with BSPP type. So G thread and BSPP thread are basically the same, and all used in non-sealing applications. But BSPT is often used in sealing connections.
After we understand what the BSP and G threads are, let’s recognize their details, differences and typical applications in actual cases.
What is BSP Thread?
BSP thread is a British standard, so it always used in the countries that apply to he British standard. And it is mainly used in pipeline and industrial line systems. The design of threads is mainly for the convenience of installing pipe fittings. There are two types:BSPP (parallel) and BSPP (tapered).
BSPP (British Standard Pipe Parallel)
The thread of BSSP is parallel, which is often called G threads. When stall this thread types often need to use sealing gaskets or O-rings for sealing purposes.BSPP threads themselves do not have sealing properties.
BSPT (British Standard Pipe Tapered)
The shape of is BSPT threads tapered which has better sealing effect when screw up. This thread type is always used in gas lines and other high pressure systems which need security and leak-proof seal.
What is a G Thread?
G thread is parallel BSPP thread, used in non-sealing applications.“G” is from German terminology “Gewinde”, which means thread. G thread is same to BSPP thread, and all comply with the same size and thread pitch. They all need sealing gaskets or O-rings to seal instead of their own threads themselves.
Differences Between BSP and G Threads
On the face of it, BSP and G thread are the same, but they have big differences of sealing usages and abilities. Although both of them are parallel, G thread is just a type of BSPP thread, and mainly used in applications using external sealing mechanisms such as gaskets or seals.
| Feature | BSP (British Standard Pipe) | G Thread |
| Thread Type | Can be BSPP (parallel) or BSPT (tapered) | Parallel (BSPP type) |
| Sealing | BSPT (tapered) provides self-sealing, BSPP (parallel) requires a gasket | Does not seal by itself, requires an external seal |
| Applications | Plumbing, gas lines, hydraulic systems | General applications, non-sealing |
| Common Usage | Found in both BSPP and BSPT variations | Mainly used for non-sealing pipe fittings |
BSP vs G Thread: Which One to Choose?
The first thing you need to consider is whether this project require sealing, when you want to choose between BSP thread and G thread. If this project is in high pressure, the higher sealing ability is required, you can choose BSPT with some external seal or BSPP. If your project doesn’t need self-sealing thread, G thread maybe a proper option.
G Thread Applications
G threads is widely used in some lower pressure projects or projects that do not require good sealing, such as:
- Water Supply Systems:Always used in some projects which seals wiht external seals (such as O-rings).
- Hydraulic Systems:Often used in the equipment that doesn’t need thread itself to seal.
- Automotive Applications: Always used in non-sealing fittinngs for gas and air systems.
BSPP and BSPT Applications
- BSPP (parallel): Used in the applications that seal by O-ring or washerto proof link.
- BSPT (tapered):Often used in gas line, pipe line and some other applications that need seal by itself.
How to Identify BSP and G Threads?
From the outside, BSP thread and G thread look alike. You can distinguish them by the screw pitch, diameter and the thread angle.
Pitch and Diameter:：BSP thread always have standard screw pitch (the thread number in every inch)and diameter. You can distinguish them by measure the thread size.
Thread Angle：both the thread angle of BSPP thread and G thread are 55°.
Sealing Type：G threads cannot self seal and require external seals such as O-rings.
BSP vs G Thread Size Chart
| Size | BSP Thread (BSPP) | G Thread |
| 1/8” | BSPP 1/8” | G 1/8” |
| 1/4” | BSPP 1/4” | G 1/4” |
| 3/8” | BSPP 3/8” | G 3/8” |
| 1/2” | BSPP 1/2” | G 1/2” |
| 1” | BSPP 1” | G 1” |
Conclusion
In summary, BSP threads and G threads have a lot in common. The main difference is the sealing ability and the use cases.G threads belong to BSPP, widely used in non-sealing application. Different from that ,BSPP thread is always used in the pipeline and industrial applications which match sealing gasket or O-ring. The more you know them, the better decision you can make .
It is critical to choose the right thread type to make sure the project can finish on time, be security, and non-leak. Before continuing with the installation, please make sure to check the thread specifications.
