This magnetite breaks loose from the piping walls and often collects on the seal components. It can be recognized by its black or reddish color and its attraction to a magnet. It will wear the sliding elastomer sealing surface. Loose magnetite is very common in new water systems. The problem will eventually clear its self up after the system has been in use for about a year and the ferric oxide has formed into a stable layer.
Hot water is dangerous.
The leakage will be invisible as it flashes to steam. If the hot water is part of a condensate system it may have to be sealed under vacuum conditions. In order to seal this product effectively, you must address all five problems at the same time. We will begin by learning how to pick the correct materials for the seal components, then we will choose a seal design and finally apply the correct environmental controls to insure that the above problems are being addressed. Plated or coated faces should not be used in this application.