Subclass Subgroup Patent
F16L 3/02 12169035
  3/1058 12169036
  9/147 12169043
  9/20 12169044
  33/2076 12169037
  37/092 12169038
  37/252 12169039
  55/1018 12169040
  55/1645 12169041
  58/181 12169042