Thread Identification

At Ashford Instrumentation Ltd we are often asked to identify the dimensions of the threads on the instruments we supply.

The following information has been prepared to help our customers identify the thread on the instruments they have on site.  

BSP Parallel Threads 

Usually initially identified as having a spigot at the bottom of the connection block (although not all will have this). This thread is sealed on the face at the bottom of the block and will usually require a sealing washer. The threads visually should be seen to be parallel when viewed side on. Male parallel threads should always be fitted into a female parallel socket.  

Nominal Size (Inches)   - Turns Per Inch – Major Diameter (Inches)1/8”                                       28                          0.383          ¼”                                         19                          0.518         3/8”                                       19                         0.656   ½”                                         14                         0.825    1”                                          11                         1.309

BSP Taper Threads 

Usually initially identified as having no spigot at the bottom of the connection block (although not all will have this). This tapered thread is sealed on the thread usually using PTFE tape and will not usually require a sealing washer. The threads visually should be seen to be tapered from top to bottom when viewed side on. The taper is ¾” per foot. Male taper threads should always be fitted into a female tapered socket.   

Nominal Size (Inches)   - Turns Per Inch – Major Diameter (Inches)1/8”                                       28                         0.383   ¼”                                         19                         0.518   3/8”                                       19                         0.656   ½”                                         14                         0.825    1”                                          11                         1.309

NPT (Taper) Threads 

Usually initially identified as having no spigot at the bottom of the connection block (although not all will have this). This tapered thread is sealed on the thread usually using PTFE tape and will not usually require a sealing washer. The threads visually should be seen to be tapered from top to bottom when viewed side on. The taper is at an angle off 1o 47’. Male taper threads should always be fitted into a female tapered socket.   

Nominal Size (Inches)   - Turns Per Inch – Major Diameter (Inches)1/8”                                       27                         0.405   ¼”                                         18                         0.540   3/8”                                       16                         0.675   ½”                                         14                         0.840    1”                                          11.5                      1.315

CONTACT US

Ashford Instrumentation Ltd
Unit 3 Fairview Industrial Park
Hamstreet Road
Ruckinge
Kent
United Kingdom
TN26 2PL

Tel: 0044 (0)1233 730999
Fax: 0044 (0)1233 731133
Email: sales@ashfordinstrumentation.com


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