| 165 / | HD | HEAT EXCHANGE |
| DIG 51 | DD | HAVING EXPANSION AND CONTRACTION RELIEVING OR ABSORBING MEANS {2} |
| DIG 52 | DD | .~ For cylindrical heat exchanger {6} |
| DIG 63 | DD | .~.~ Cylindrical heat exchanger fixed to fixed end supports {2} |
| DIG 65 | | .~.~.~ Bent cylindrical heat exchanger {1} |
| DIG 66 | DD | .~.~.~.~> Coiled |