Difference Between BSP Thread and NPT, G, R Thread

1. What is BSP thread size?

BSP (British Standard Pipe Thread) is a British 55° pipe thread with a rounded top and root, used in Europe and the British Commonwealth.

1/4" BSP Thread: 1/4 represents the inside diameter of the tube connected to the female thread in inches.

BSP Thread Dimensions Chart
Thread Size	Threads per (Inch)	Pitch		Major Diameter (O.D)		Minor Diameter (I.D)		Gage Length
		Inch	mm	Inch	mm	Inch	mm	Inch	mm
1/8	28	0.0357	0.907	0.383	9.728	0.3372	8.565	0.1563	3.97
1/4	19	0.0526	1.337	0.518	13.157	0.4506	11.445	0.2367	6.012
3/8	19	0.0526	1.337	0.656	16.662	0.5886	14.95	0.25	6.35
1/2	14	0.0714	1.814	0.825	20.955	0.7336	18.633	0.3214	8.164
3/4	14	0.0714	1.814	1.041	26.441	0.9496	24.12	0.375	9.525
1	11	0.0909	2.309	1.309	33.249	1.1926	30.292	0.4091	10.391
1¼	11	0.0909	2.309	1.65	41.91	1.5336	38.953	0.5	12.7
1½	11	0.0909	2.309	1.882	47.803	1.7656	44.846	0.5	12.7
2	11	0.0909	2.309	2.347	59.614	2.2306	56.657	0.625	15.875
2½	11	0.0909	2.309	2.96	75.184	2.8436	72.227	0.6875	17.463
3	11	0.0909	2.309	3.46	87.884	3.3436	84.927	0.8125	20.638
4	11	0.0909	2.309	4.45	113.03	4.3336	110.073	-	-

2. What is NPT thread?

American National Standard Pipe Thread is abbreviated as national pipe thread standards, and the thread angle is 60°. According to the shape the thread is divided into sealed straight pipe threads and sealed taper pipe threads, different shapes of male and female thread shorts are also different, such as NPT (National pipe taper), NPS (National pipe straight), NPTF (National pipe taper- fuel and oil) or NPSC (National pipe straight-coupling) and so on.

1/2" NPT Thread: 1/2 represents the inside diameter of the tube connected to the female thread in inches.

3. What is the difference between npt and bsp thread? Are NPT and BSP threads compatible?

Thread shape and angles differ and are not compatible.

NPT is a 60° American Standard tapered pipe thread with a tapered profile and a flat top and root of the thread.

BSP is a 55° British seal pipe thread with a rounded top and root.

4. What is the difference between BSP, BSPP, BSPF, BSPM and BSPT thread?

BSP threads are divided into BSPP straight pipe threads and BSPT taper pipe threads by shape.

BSPP (British Standard Pipe Parallel) is a sealed connection 55° straight pipe thread. In the VPC fitting series, BSPP threads are available with O-Ring by default.

BSPF (British Standard Pipe Fine Hand Taps) is the British non-sealed connection 55 ° fine thread straight pipe thread, but now basically are used BSPP thread directly refers to the BSPF thread. BSPF thread in the new standard BS EN ISO-228-1 can be replaced by G thread. BSPP=BSPF=G thread

BSPT (British Standard Pipe Taper) is a 55° tapered pipe thread for British Sealed Connections, also known as PT thread (with O-ring by default in the VPC fitting series), which has a thread taper of 1:16 and is generally used in the water and gas industries. The old standard for BSPT was BS 21, and in the new standard, BS EN 10226-1, it can be replaced by R (Rc) thread, i.e. BSPT (PT) and R (Rc) threads are compatible. R (Rc) threads can be substituted in the new standard BS EN 10226-1. BSPT( PT) = R（Rc）(The default BSP refers to the BSPT thread in the VPC pipe series.)

BSPM (British Standard Pipe Mechanical) is an old standard for British threads. It can be replaced by G thread in the new standard BS EN ISO-228-1, that is, BSPM, BSPF, BSPP, and G thread are compatible.

5. What is G & ZG thread size?

G (from Gas pipe/German Gewinde) is a British non-sealing connection 55° straight pipe thread, which can be sealed by adding an O-ring or gasket. In the VPC connector series, the G thread comes with an O-ring by default.

There are two types of G threads: male and female. G threads with O-rings are suitable for low-pressure pipelines that bear static loads. In low-pressure pipelines that bear static loads, the elasticity and compressibility of the O-rings can fill the gaps between the threads when tightening, forming an effective seal. At the same time, the elasticity of the O-ring can compensate for pipeline displacement caused by temperature changes or vibration, further enhancing the sealing effect and preventing media leakage.

ZG is a 55° tapered pipe thread for sealed connection. The taper is 1:16. It is generally used for water pipe fittings and is commonly used in European countries. ZG thread can be replaced by Rc (female thread) in the new standard, that is, ZG and RC threads are compatible.

6. Are G threads compatible with NPT?

NO. The angle and thread pitch (threads per inch) of G threads and NPT threads are different.

7. What is R thread size?

R (from German rohr) thread is a collective name for 55° sealed pipe threads with a rounded top and root.

Rp - 55° sealed female straight threads, these threads are mainly used in high temperature, high pressure environments or inside lubrication systems.

Rs - 55° sealed straight male threads

Rc - 55° sealed tapered female thread with a taper of 1:16, nowadays commonly referred to as R thread.

R1 - 55° sealed tapered male thread. Straight female thread (Rp) + Tapered male thread (R1), "straight/taper" fit.

R2 - 55° sealed tapered male thread. Tapered female thread (Rc) + Tapered male thread (R2), "taper/taper" fit.

8. What is the difference between BSPT and NPT thread?

The angle and pitch (threads per inch) of the threads are different. BSPT is 55° and NPT is 60°.

9. How do you identify BSP threads?

10. Is BSP and G the same?

In a sense it's the same. According to the latest standard BS EN ISO-228-1, G thread is the same as the BSPP thread standard under the BSP thread branch and can be used compatible. At the end of the article there are the latest standards for various threads to help you differentiate between them.

11. Are R and G threads compatible?

Incompatible, the two follow different thread standards. R (Rc) is a 55° tapered female thread, and G is a 55° straight pipe thread.

12. Is BSPP the same as BSP?

BSPP is a branch of the BSP British 55° pipe thread standard. BSPP is a British 55° sealed straight pipe thread.

13. What does G mean in pipe size?

For example: G1/4",1/4 refers to the inner diameter of the tube in inches.

14. Can you connect BSPP to NPT?

No, the angle and pitch (threads per inch) of the two threads are different.

15. What is difference between BSP and BSPT thread?

BSPT is a subdivision of the BSP British 55°Pipe Thread standard.

BSPT is a British 55° sealed tapered pipe thread.

16. Are BSP and BSPT interchangeable?

Most factories use BSP to refer to BSPT, but the actual thread measurement data prevails.

17. BSPP vs BSP vs G vs PF thread ?

BSPP, BSPF (PF) and G threads are all BS EN ISO-228-1 standard and can be compatible. All four are imperial threads.

18. BSPT vs PT vs R vs ZG thread?

BSPT(PT), R（Rc） and ZG threads are all BS EN 10226-1 standard and can be compatible.

G, BSPP, BSPT, R threads international standards

G - British unsealed parallel pipe thread (International Standards: BS 2779, BS EN ISO 228-1, ISO 7-1)

BSPP - British Standard Parallel Pipe Thread (International Standards: BS 2779, BS EN ISO 228-1, ISO 7-1)

BSPT - British Standard Pipe Tapered Thread (International Standards: BS 21, BS EN 10226-1, ISO 7-1)

R (Rp, Rs, Rc, R1, R2) - British tapered pipe threads (International Standards: BS 21, BS EN 10226-1, ISO 7-1, DIN 2999)

All four are part of the Whitworth Thread family.

Thread specifications and data may vary for different types of machines. If you can't confirm the thread size you need please Contact Us, VPC Pneumatic will help you choose the best thread component.

Bibliography：

Wikipedia《National pipe thread》

Wikipedia《British Standard Pipe》