dk nkf - Nordisk Konservatorforbund Danmark

Figure 16 Ferrous chloride and iron response to relative
humidity
Figure 17 β-FeOOH and iron response to relative humidity
Figure 18 Response of washed and unwashed beta ferric oxyhydroxide
at 20% RH
each. This continued a style of teamwork developed
in the initial investigative phase of the work. [4]
While this work was continuing, David Watkinson
and Mark Lewis at Cardiff University were
commissioned to establish the appropriate level
of RH for the ship. Their work looked at the rate
at which iron and corrosion products corrode at
various levels of RH. [5]
212
Figure 19 The ship before treatment
Figure 20 The ship after treatment
The initial work looked at ferrous chloride and
suggested that the ship would be stable at around
20% RH. However, when the role of beta ferric
oxy-hydroxide (β-FeOOH) was considered it
appeared that the required RH level was closer
to 15%.
Obviously running costs would be significantly
lower if the iron could be kept at an RH of 20%
so Watkinson and Lewis [6] looked at the response
of washed and unwashed β-FeOOH because, as has
been previously noted, the ship had spent 30 years
away from the sea being regularly washed by rain.
Furthermore, it appeared that there was relatively
little β-FeOOH .
It was finally decided to design the dehumidification
plants to have the capacity to deliver an RH of 15%
but to run them at 20% and monitor the results.