Chilled and Steam Pipe network of Air Handling Units 1

[flexiblycool]

We routinely flush new chilled water pipe networks by bypassing all the equipment such as chillers, FCUs, etc, then do the removal of rust and finally introduce corrosion inhibiting chemicals in preparation of commissioning the system. I would like to know the procedures for flushing and chemical treatment of piping to and from the steam humidifiers in our Air Handling Units. The contractor says the flushing will be done by steam and that of the condensate return lines by gravity flow. I thought the flushing velocity of the water has to be 1.5 meters per second, so I doubt if gravity flow would be able to expel the debris inside the pipes from the welding process. Where can I find detailed guidelines of how to flush our welded black steel pipes of the steam network all the way from the boiler to the Air Handling units where we have steam humidifiers?

 

[ChasBean1]

Don’t look for detailed guidelines. Why does everyone need a written authority with or without merit to determine every last bit of thinking for them, to dispel them of any liability?

How will you force 1.5 M/S through a condensate line? By taking dry ice to all of the traps in the system?

Codes and standards are there to prevent morons from killing or maiming people. Don’t look to codes, standards, engineers, architects, and local officials to do every last shred of thinking for you.

Apply steam and flush the system until you have a good sample.

 

[ChasBean1]

That sounded crusty and jaded, my apologies - ...

 

[SAK9]

No CB you were spot on..I do not need a detailed guide line to wash my undies in the machine.

 

[flexiblycool]

ChasBean1
The amusing rhetoric aside, I wish to find out if there are minimum standards and quantitative/qualitative engineering procedures of flushing steam lines (not just from the point of view of avoiding liability). Or is the procedure summed up and practiced like you have done? What does flushing the steam lines till you have a good sample mean? What about the welding spoils that might be lying on the inside of the pipe and yet clean steam comes out of the pipe? Is steam able to push the solids through large and long pipe network like the higher momentum of water can?

 

[RossABQ]

Steam and condensate lines are generally flushed by opening the drain valves on the drip legs, in my experience. You absolutely do not want to go thru the traps or their strainers! If you have bypasses on the trap stations, open them after the steam sections are clean. My experience has been that steam piping is filthy, all kinds of grease, rust, and occassionally rags, safety glasses, etc. To blow thru the drip leg drains, you need some temporary piping to a safe location, and need to operate at a reasonably low pressure -- say 5 psi.