In Europe there are two main thread types which are of common use.

The first thread type is according to ISO228-1, where both female and male threads are parallel and the pressure-tight joints are not made on the threads because of the gap between the two threads. This fact makes the use of an appropriate sealing material necessary in order to avoid a leak from the junction. These threads acc. to ISO228-1 are also commonly called “G-threads”.
The second thread type is according to EN10226-1, where the female thread is parallel and the male thread is taper and the pressure-tight joints are therefore made on the threads. In this way, the tightness can occur directly on the thread. 
However, in practice, specific sealant materials are widely used in order to guarantee the absence of possible leaks.
The male taper thread acc. to EN10226-1 is also commonly called “R-thread”, while the female thread acc. to EN10226-1 is called 
“Rp-thread”.  
Some of our ball valve series are manufactured so that the female threads are in conformity to both ISO228-1 and EN10226-1 standards. This because the two standards partially overlap on the prescribed tolerances. Please find here below the tolerance scheme referred to ¾” threads. For additional information about our product lines with this feature, don’t hesitate to contact you usual sales representative within BONOMI INDUSTRIES or our Engineering Center.

1

DISCLAIMER: The information contained herein are provided in good faith and are deemed accurate at the date of this declaration. We do not carry out any specific chemical or mechanical analysis on products, but periodically update the situation through our suppliers, websites and all available information sources, to the aim of guaranteeing the classification of our products in respect of safety and regulations requirements. Our Company makes no warranties, expressed or implied, and assumes no liability in connection with this information