| 摘要 |
A boiler heat exchanger comprises a flueway and a waterway provided through at least one cast metal heat exchange chamber, which chamber has at least one core opening 15 closed by a plug 16 fitted other than by screwing into the core opening. The plug 16 may be fitted by first treating the plug cryogenically, and then locating the plug in position in the core opening of the heat exchange chamber so that as the plug warms up to the ambient temperature it expands and tightly closes the opening. Alternatively, the plug comprises a disc which is force-fitted into the core opening, sealing means being provided between the rim of the plug and the edge of the opening to close same. <IMAGE> |
