Safe operating pressure to work on H2 Line 1

[limaruoo]

HI all,

I work at a chemical plant and we have small hydrogen leak coming out of this long hydrogen line among some fittings.

One of the main issues with H2 besides its wide flammability range is that when you have to purge the line of hydrogen you have to use helium to purge the line before H2 is reapplied. this ensures there is no oxygen that entered the line while the line was down for repairs

my question is what is the lowest pressure the line can be safely worked on?

Right now it has 100 psig of pressure in it. we have multiple gas monitors around the area to ensure the leak doesn't get close to 25% of the LEL. The area is now restricted

We would like to lower the pressure to a safe pressure so we can work on it without having to do a full helium purge.

I tried looking up pressures of gas that can cause injury to personnel and can't find much. the concern is if someone is working on the leak (by tightening fittings) we are worried if the gas pressure were to spray out onto the worker. Obviously, a 600# leak can cause injury but what about 50#? 20#? 10#? I'm aware this depends on multiple factors as well.

any advice?

 

[LittleInch]

Shvet,

The problem with your solution is that this is normalising failure. A joint which leaks has failed.

Then the line between an acceptable leak or even e fire starts to get stretched. You say a finger sized flame. Then why not an arm sized flame? Or a leg sized one?

That's the problem with normalising failure. It just feeds on itself.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[limaruoo]

All,

I been away on work travel and i finally got back home.

I read all your replies and I made the decision to not have my maintenance team work on the line until it's fully purged with nitrogen.

I appreciate all the advice and support!

 

[A8yssUK]

@shvet

I am sure we'll see you and your team in an upcoming CSB (

https://www.csb.gov/)

video!

Absolutely fix hydrogen leaks... but don't fix burning hydrogen leaks run the hell away from them!!

 

[shvet]

@A8yssUK
Seems a professional is coming to this community. Tell us more how many real hydrogen involved process facilities you are well familiar with and the cases those are practicing.
Note that no one on this thread has shared us a story how a 10 millions USD were wasted to defeat one finger-sized hydrogen leak. While this forum gathers different people from all around the world. Why have a such upstart, as shvet is, not been beaten by a so simple point?