To limit the probability that:
- inadequate size will lead to back pressure at relief
valve outlets, which could lead to interference with proper pressure
relief for protected devices,
- inadequate rigidity, inappropriate slope, inappropriate
termination or excessive space between the end of the pipe and a floor
drain will lead to misdirection of vented water,
- inadvertent blockage, connection or extension of pipes
will lead to inoperability of relief systems, or
- use of inappropriate materials will lead to an inability
to withstand temperatures to which it may be exposed, which could
lead to failure of pipes.
This is to limit the probability of
exposure to hot water or steam, which could lead to harm to persons.