4000 psig leak

Of what? Compressed Gas... about 5 miles (Lot of build up kinetic energy and if that blows, they will find parts of your building 4 miles away.)

Of water? not at 350c, that would again be compressed gas

a liquid? not sure .. the size of the leak would determine the distance it would shoot wouldn't it?

<...Of water? not at 350c, that would again be compressed gas...>

Actually, the saturation pressure of water at 350degC is about 166bar, from steam tables, or just north of 2300psig so it would still be liquid water at 4000psig and this temperature. Of course, it would turn to superheated steam upon departure through the leak.

5 miles is still a good distance!

at 4000 psi, water will be a gas by definition. Not being picky or mean.

At stated conditions, it is above the Critical Point pressure and below the Critical Point temperature, according to Mayhew & Rogers, "Thermodynamic and Transport properties of Fluids", Oxford Basil Blackwell, 1976 ISBN 0 631 96400 2. So how does it work out as a gas by definition (just curious)?

once you are above the criticle pressure, no matter what the temperature is, it has the internal enegy of a gas. There is no heat of vaporization, the energy is continous. Its physical properties will approach a liquid.

I am just curious on this topic. Is there a link to a good phase diagram for water? I could not find one in my quick search that shows the phase of water at that temperature and pressure.

BTW, I like the 5-miles...

Try this site, it is a fund of useful information and has all the tables you need, not sure of a diagram. http://www.spiraxsarco.com

Interestingly their tables only go up to 214 bar (3100 0dd psi). I find it strange that anyone would want to pump hot water at that pressure.

Wouldn't the second pipe around the first just be sliced open by the leak? (unless you meant squeezing the second pipe around the first to prevent the leak occurring). Not a rhetorical question - I've never dealt with hp steam - just asking out of interest...

Depends on how big the leak is and how close the pipes are togther. If exposed to the leak long enough it could erode its way through. By that time however you would know there was a leak and have hopefully done something about it. The idea is to keep sensitive areas from being directly impacted by the stream of high pressure gas. Basically you are making a shield of sorts to deflect the gas. Its not a very common thing, but its has been done in the past.

Thanks - & I liked the broom trick by the way :)

Is it necessary to go to 4000psig? In other words, is this normal operating conditions or a special consideration?

If it's a steam leak:

1. Use the broom (for the poor fool that has to go in the space and start closing manual isolation valves).

2. Run like heck because it will cut & cauterize simultaneously.

Regarding a good table to reference....

http://www.spiraxsarco.com/resources/steam-engineering-tutorials/steam-engineering-principles-and-heat-transfer/what-is-steam.asp