they will be by the time u get sorted tho...
depending on how your hop filter works, you could be able to use a fine mesh wine straining bag to surround it? filter the fine stuff out in the kettle instead though not all boiler filter heat source combos will allow that approach.
http://www.amazon.co.uk/dp/B005SSTAWI/?tag=skimlinks_replacement-20
while 100% SS is nice n shiny modern brass plumbing bits are way cheaper and with ultra low lead levels are highly unlikely to leach any lead out, and the threads employed in 15mm compression fittings are 1/2" bsp compatible
for SS pipe fittings visit bes.co.uk
http://www.bes.co.uk/products/165a.asp
and im sure a brass version of the yfilter is suitable for potable water
to join 2 x Female threaded bits a 'nipple' is the fitting needed, a parallel nipple is just a threaded bit of tube , a hex nipple will have 2 x tapered threads and a spannerable
hex in the centre separating the threaded ends
use lots of sealant tape ptfe.. either will work..