HPS line steam blowing

[Toinmingos]

I am working on the comissioning of a cogeneration powerplant where we have an HPS steam line 12" diameter 300m long connected to an existing steam header which feeds a steam turbine and other process equipments. The question is: should the steam blow be performed with the line insulated or not insulated?

 

[DSB123]

Toinmingos,
What is a steam blow trying to do? Answer this and you will then know whether or not piping insulation should be installed or not.

 

[Toinmingos]

In spite of the greatest care being taken during installation and welding of the steam lines, it is inevitable that foreign matter will remain in the systems and the inside surfaces of the steam pipes must be cleared of loose rust, scale, coatings, dirt and foreign matter to such an extent that the components connected thereto can be started up safely.

To achieve the required degree of cleanlinees the piping system up-stream of the turbine is normally blown using steam velocities greater than those in full load operation.

 

[DSB123]

Toinmingos,
I am fully aware of what the steam blow is for. What I was indicating is that if you know why you are doing the blow then you can basically answer your question yourself!!!!

 

[macmet]

For my own information I'd like to know people's opinions on this as I recently started working at a company where we do steam blows, although I have not yet done one myself.

I would think that the line does not need to be insulated since the purpose is to clean the inside of the pipe and the steam is not sent to the turbine anyway.

 

[vpl]

Where does the steam blow (or blowdown line, as I more commonly see it), exhaust -- to a drain tank or to the condenser? If it's a drain tank, is the tank designed to handle steam?

Will it be used only once, under cold conditions, or periodically under heated conditions? (Toinmingos implied it's a pre-operational blowdown, macmet appears to have periodic blowdowns).

Is the steam blow located such people could get injured by coming into contact with the piping or the exhaust? If you answered no, ARE YOU SURE???

Macmet -- since you're working at a plant that does periodic steam blows, maybe it's worth a visit out to the location to see what's there.

Patricia Lougheed

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