| 165 / | HD | HEAT EXCHANGE |
| DIG 532 | | HEAT EXCHANGE CONDUIT STRUCTURE {4} |
| DIG 533 | DD | .~> Composite of diverse materials {1} |
| DIG 535 | DD | .~> Helically formed |
| DIG 536 | DD | .~> Noncircular cross-section {1} |
| DIG 538 | DD | .~> With particular flow connecting structure |