×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Steam and static discharge.

Steam and static discharge.

Steam and static discharge.

(OP)
Hi

We regularly use Nitrogen from trasfer of material from one vessel to another via pressurisation of the vessel to trasfer along the pipe.

A project I am working on has highlighted that the opperators always combine the 5bar Nitrogen with the 9bar steam to speed things up!!!

I have read many instances where steam /condesate has been linked to static discharge leading to explosions in flamable atms.

But would the same be true of what my operators are doing with 5 bar Nitrogen and 9 bar steam?

Safe solution open to me is just incease nitrogen to 10Bar.

RE: Steam and static discharge.

The static generated by the steam is usually grounded immediately via metallic piping;- it could be an issue with plastic piping, with no grounding facility to the metallic braid of the hose ( you still could insert metallic connectors between lengths of piping, grounded to the plant grid). If you discharge Nitrogen / steam in an explosive mixture, then to be on a safe side, prevent the build-up of static with continuous metallic piping, grounded to the plant grid. Make sure to use bridges accross flanges to ensure electrical continuity, also no screwed connections!
If money is no object, look at the high tech static dissipative plastic materials to solve your concerns. However, if you can pressurize the Nitrogen to 10 bar, that's the best solution.
cheers,
gr2vessels

RE: Steam and static discharge.

They can't actually be pressurising up to 9bar- or they wouldn't be using any nitrogen at all. Increasing the nitrogen pressure won't necessarily fix the problem either.

You need to understand what pressure they are actually doing the transfer at- and what the volume limitation is on the nitrogen system at that pressure. I'd suspect they're using the steam to provide additional volume rather than pressure.

RE: Steam and static discharge.

(OP)
Hi Itdepends.

Yes you are correct, they are not pressurising upto 9 bar.

Pressure is genarally about 2 bar and trasfer takes about 10 mins when both steam and nitrogen are being used.

When only either steam (@9 bar) or Nitrogen (@5 Bar) are used it can take upto 20 mins.

RE: Steam and static discharge.

When they use only nitrogen or only steam- do they also get to ~2bar? i.e. does it just take them longer to generate the required pressure when using (only) steam or nitrogen?

RE: Steam and static discharge.

(OP)
Hi Itdepends

Yes it just takes them longer when they one only one of either steam or Nitrogen. 20 mins vers about 5/10 min

RE: Steam and static discharge.

In that cuase I'd suggest investigating the flow limiting components of the nitrogen system rather than increasing the pressure.

Chers

RE: Steam and static discharge.

(OP)
I see what you are saying. If our nitrogen system can not keep up with the required demand that could be the cause rather than lack of pressure. And increasing pressure might not have any effect.

RE: Steam and static discharge.

As an aside, I assume from the fact that this question is being asked that the system was not designed to use steam for this.  Is there an additional issue around management of change that needs to be looked at?

RE: Steam and static discharge.

(OP)
Managment of change is also been looked at. This notification that both steam and nitrogen are being used only came about when operators where asked to record trasfer data, I happened to include tick boxes for, one for Nitrogen, and one for steam.

We recived the complted sheet back, and all times, both nitrogen and steam had been ticked.

Operators being operators! we asked them to confirm their actions, and yes they do both because "it is faster"

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources