Steam Main Design
A steam line should always slope downwards in the direction of the flow of steam. (Figure 4.4) This ensures that condensate flows towards the next steam trap collecting point. This helps keep steam dry and prevents water hammer.
Making steam flow up hills should be avoided as condensate will flow down due to gravity in the opposite direction to the team. This can cause condensate to mix with the steam and produce wet steam rather than being removed. If steam must be routed vertically, the pipe should be oversized. (Figure 4.5)
This allows the condensate to fall against the flow of slow moving steam. Steam traps and condensate collecting points should also be provided at the bottom of the lift to ensure that condensate can be removed (Figure 4.6)
Concentric reducers should not be used on steam lines as they restrict the removal of condensate by acting as a dam wall. (Figure 4.7) The resulting pool of condensate can cause water hammer as previously described. If the diameter of pipework has to be reduced to fit control valves or reducing valves, eccentric reducers should be used.