摘要 |
Method of making a lined metallic water tank for a water heater, using the steps (a) making a metallic tank pre-form which is open at one end; (b) inserting a collapsible container through the open end into the pre-form; (c) drawing a vacuum on the container to displace the container away from the open end; (d) enclosing the open end to form a completed water tank while continuing to draw vacuum; and (e) applying pressure, within the container to expand the container against the inside surfaces of the completed tank.
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