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[deltawolf]

Good day all

We need to do a steam blow out on a new High pressure steam line.

Normal opperating pressure is 43barg, and 425°C. max flow 317286 kg/h, Pipe size inside the plant is 16" sch 40 (about 80m), outside plant limits is 24" (about 1000m).

The steam lines connects to an existing steam header.

The idea for the blow out is to use the existing steam header to pressurize the new pipe and open a temporary valve at the end of the new pipe and and do the blow out that way (i.e. reverce flow)

My question is:

What size should the temporary pipe (and valve) be? Should it be the same as the 16" line or can we go smaller? And how do I do the calculation, as it will not be a steady state flow.

[Zauberberg]

Of course you can (and you should) go with a smaller size line, as you are not interested in transporting certain quantity/flow of steam, but rather to pressurize the new line and then purge it. No need for a 16" line for that purpose.

As said on a few occasions in these forums, there is no flow that is to be calculated. You are purging and commissioning the line. You use whatever amount of steam you need to make the line free of debris and rust - why should you be interested in flow?