Condensate formation in start-up steam line.

[nRGee]

Greetings...

I came across a piping system wherein minimum distance is not followed on downstream of isolation valve on start-up steam line. Please refer to the schematic attached herewith.

During normal operation, Isolation valve on start-up steam line will be kept closed and it will be floating on the main steam line which is at around 40 Kg/cm2.

Distance between the isolation valve and the mixing point is around 14 meters. There is a break flange on main steam line.

I'm expecting condensate formation on downstream of the isolation valve on start-up steam line and eventual hammering in main steam line. If it is severe, it may lead to damaging the break flange and leaky flange.

Please share if there is any guideline or thumb rule on minimum distance to be maintained between the isolation valve and main steam line.

 

[shvet]

As per my experience in a cold climate 0.6 meters (2 feet) is a common practice.

 

[MJCronin]

In your EXCEL PID, which way is the piping sloped ? ... It should be sloped toward the HX.

It is perfectly acceptable to have "start-up condensate" from a smaller steam line drain intoa (trapped) larger line

Can you provide any recent pictures ?.... Why not ??? ... Steam piping systems are not "company confidenetial" like your MBA boss has been telling you

Have you physically gone out and checked the line slope ?

No actual original PIDs available, right ?.... They were all discarded by the maintenance department of the previous plant owner, correct ????

MJCronin
Sr. Process Engineer

 

[nRGee]

@MJCronin

It is a new plant, close to pre-commissioning stage (luckily there is no possibility of "previous plant owner's maintenance department discarding the important documents". I know the pain).

secondly there is no MBA boss policy here... we move up the ladder with experience.

yes I'd been there physically to punch-list this system...that's when I identified. It is not slopped towards the exchanger.

By the way, it's not an EXCEL PID, I have used DRAW.IO to simplify the schematic for ease of understanding. It is a cool web based tool, you may try that too.

I will be glad if it works without causing any problem as you mentioned.

Thanks.

 

[mk3223]

It's for sure that the condensate is to be on the new steam line, and:
1. the condensate is to be formed on the dead end steam line "before" the closed valve
2. the steam pipe of new 14meters "after" the closed valve is to be hot "similar" to the existing live steam pipe.

The design is missing a separate condensate collection piping with steam trap on the new steam line system, which will remove the condensate formed on the steam line during the start-up and normal operation as well.