Ticket #5979 (new)

Opened 17 hours ago

Congratulations! You can get a $50 Verizon gift card!

Reported by: "Congrats!" <Congrats@…> Owned by:
Priority: normal Milestone: 2.11
Component: none Version: 3.8.0
Severity: medium Keywords:
Cc: Language:
Patch status: Platform:


Congratulations! You can get a $50 Verizon gift card!



The first Yarrow water drums or "troughs" were D-shaped with a flat tubeplate, so as to provide an easy mounting for the tubes. The tubeplate was bolted to the trough and could be dismantled for maintenance and tube cleaning.

This D shape is not ideal for a pressure drum though, as pressure will tend to distort it into a more circular section. Experience of boiler explosions had shown that sharp internal corners inside boilers were also prone to erosion by grooving.

Later boilers used a more rounded section, despite the difficulty of inserting and sealing the tube ends when they were no longer perpendicular. These later drums had a manhole in the ends for access.

The circulation in a Yarrow boiler depended on a temperature difference between the inner and outer tube rows of a bank, and particularly upon the rates of boiling. Whilst this is easy to maintain at low powers, a higher pressure Yarrow boiler will tend to have less temperature difference and thus will have less effective circulation. This effect can be counteracted by providing external downcomers, outside the heated flue area.

Although most Yarrow boilers did not require downcomers, some were fitted with them.

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