Thanks for contacting Technical Help. The nut on the spigot end of the service valve has an internal 1/2" BSP thread so providing the flexi tail has the same thread, yes, but you will have to also use a fibre washer to provise the seal between the two parts. The opposite end of the service valve also has a 1/2" BSP thread, but is designed for a compression joint to be made.
I hope this answers your question,
Pegler Tech Help
Date published: 2015-11-09