7 replies to this topic

[MacProcess]

We usually specify steam out condition in equipment data sheet for equipment design.

 

However, I haven't seen pipes have steam out condition even though refinery heavy hydrocarbon pipes will be steamed out.

 

Have you experienced that you specify steam out condition in piping schedule?

 

If not, please tell me the reason why.

 

Thank you.

[Nirav]

Yes. We do specify steam out conditions to lines as well.

 

This is generally indicated on piping line list. A separate column is specified to just say "yes" or "no" to the line with respect to "Steam Out". The condition of steam out generally remains same e.g. Full Vacuum @ 150 °C (LP Steam condition). Sometimes, it's considered as "half vacuum" (HV) also.

[Himanshu Sharma]

Hey there !

 

I echo that as well ,all HC lines are designed and specified for steam-out although the steaming out condition specifications remains yet another topic of discussion.

 

Thanks and Regards

Himanshu

[Dazzler]

Its important to indicate where steam will be used such as on the "line list", not just for selection of suitable materials of construction and their design conditions, but also to be sure that any paint or insulation materials are suitable also, and thermal expansion may need to be allowed for in the choice of pipe supports.

 

Dazzler

[ChemE Babak]

We usually specify steam out condition in equipment data sheet for equipment design.

 

However, I haven't seen pipes have steam out condition even though refinery heavy hydrocarbon pipes will be steamed out.

 

Have you experienced that you specify steam out condition in piping schedule?

 

If not, please tell me the reason why.

 

Thank you.

 

The question that has not been answered is, "Why are pipes steamed out?"

 

Pipes are steamed out to remove air, not necessarily for steam cleaning.  The line list reflects that steam is used for that purpose.  Each process area has different methods for air purge, for example with fuel gas, N2 or water.  That being said for a pipe that is not designed for steam out and the company changes its purge technique to steam, then the wall thickness may not be enough to support the vacuum conditions.  Also as Disle commented, if it is not designed for steam out and it is steamed out, the thermal growth could possibly rupture the pipe or the condensation could collapse the pipe.

[fallah]

Agreed with Babak...in oil and gas industries before any maintenance work and in order to purging HC content and chemical residues, relevant piping would be blown through with low pressure steam where sufficient steam is available...

 

It's worth to mention that for piping systems in which operating temperature is lower than steam out temperature care should be taken for piping system flexibility as it might be subject to failure due to over-stress following to excessive displacement ...or it might be subject to buckling due to vacuum condition following to condensation... 

[manojkaila]

Dear all,

 

1 Normally in Piping line list what we mention is for the cleaning or percommissioning , commissioning purpose. Like N2, Water, Air, 

 

2 Normally the purpose of steam out is what Fallah said is mainly for Hot work ( welding) or heavy cleaning. This has the separate criteria to be considered before the steam injection like type of support, type of insulation, use of internals like valves,PSV, etc 

 

If steam our is regular practice eg in Heavy oil service then it should be considered during design.

 

Good Luck

 

Manoj 

[Ganesh Buddha]

steaming out HCs is good practice, before taking an equipment for maintenance. an in hydrocarbon industry the equipment fulfills the criteria for steaming out...

 

but steaming out the air after maintenance is pretty much a futile and time taking process...

 

instead the air can be flushed out by HC gas if available...