| 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 53 | DD | .~.~ Flexible or movable header or header element {3} |
| DIG 58 | | .~.~.~ Movable tubesheet (e.g., floating tubesheet, etc.) {1} |
| DIG 59 | DD | .~.~.~.~> Tubesheet connected to enclosure by expansion joint |