[Christy Bohannon]

We do have both a procedure and SIS to inject emergency steam and cut fuel gas temperature in a low flow situation. What I am evaluating is when it is ok to re-introduce feed / cut back emergency steam to velocity steam. If the pump simply cavitates, I assume you would not want to shut it down even if the skin temps are a little high, but you would want to keep as much steam going through the passes as possible. If the pump trips, at what temperature / other process condition do you want to re-start the pump?

[Christy Bohannon]

How does clarified oil help? What are your specs on this?

[Christy Bohannon]

We are not completely finished with the designs yet (we are installing in January) but we are also planning on eliminating that bottom flange. That is the only real cause of leaking I have heard about. Like you, we are also planning on going in at 90 deg. I was worried about impengement at first, but our engineering analysis shows that there shouldn’t be a problem.

[Christy Bohannon]

I agree that we only get a limited warm up by going to blowdown.

No, we do not go through the discharge valve through the warm-up line when putting the pump back in service after maintenance (for normal swaps we do this). We don’t do this because we were cavitating the pump by sending cold material through the suction line to the on-line pump. Instead, we open the min flow spillback to the fractionator feed line and flow from the suction of the pump we are trying to put on-line to this back to the fractionator. We do this so that we don’t send any cold material to the on-line pump. Obviously, something went wrong this time and we still cavitated the on-line pump.

[Christy Bohannon]

I agree with you, but in this case, we had the suction line open for over an hour when the pump cavitated. In our current procedure, when the pump is taken off line for maintanence, we begin by opening a line to blowdown and opening the suction line to warm to blowdown. This is when I would have expected to see a cavitation due to light material. The fractionator and blowdown DP is small, so we get limited warming this way. Next we open a spillback line to the fractionator and turn the previously off-line pump on and warm to the spillback line for a while before actually starting the pump. Right when we hit start on the off-line pump, the on-line pump cavitated. This would lead me to believe it is more of an NPSH problem, but during normal swaps, when the off-line pump is warm, we never have a problem. I know this pump is cold, but it is going to the fractionator and not to the suction of the on-line pump. Any thoughts?

[Christy Bohannon]

Out of curiosity, did you ever figure out what the problem was? We are trying come up with an explination as well as a solution.

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