Pipes And Tubular Conduits Patents (Class 138)
With pressure compensators (Class 138/26)
Thawing and freeze protection (Class 138/32)
With wear indicator (Class 138/36)
With flow regulators and/or baffles (Class 138/37)
With closures and plugs (Class 138/89)
End protectors (Class 138/96R)
Repairing (Class 138/97)
Breakjoint (Class 138/100)
Combined (Class 138/103)
Plural duct (Class 138/111)
Flexible (Class 138/118)
Distinct layers (Class 138/140)
Spirally seamed (Class 138/154)
Joined sections (Class 138/155)
Longitudinally seamed (Class 138/156)
Reinforced (Class 138/172)
Structure (Class 138/177)
Miscellaneous (Class 138/178)

Foreign Patent Art Collections

Class-related foreign documents (Class 138/FOR000)

Digests

Adhesive (Class 138/DIG1)
Glass fiber (Class 138/DIG2)
Teflon™, kel-f (Class 138/DIG3)
Air conditioning (Class 138/DIG4)
Pre-stress (Class 138/DIG5)
Corrosion (Class 138/DIG6)
Resins (Class 138/DIG7)
Bent shaped retained (Class 138/DIG8)
Cellular (Class 138/DIG9)
Metal foil (Class 138/DIG10)
Shape (Class 138/DIG11)