H2S 90%MOL : PIPING MATERIAL OF CONSTRUCTION

[macabihaifa]

Hello,
What is recommended for the piping material of construction for h2s gas at 120 C and 45 barg.

regards

 

[EdStainless]

What do the charts in various SSC standards tell you ?

 

[georgeverghese]

Small amounts of other components make a big difference to materials selection : water vapor content above or below dewpoint, chlorides, ammonia, CO2, etc. Most selections are made on the basis that there are trace amounts of oxygen even if component slate states there isnt any.

 

[pierreick]

Hi,
You may want to contact those guys:

https://www.vallourec.com/app/uploads/sites/2/2023/09/Brochure_Sour_Service_Grades.pdf

What are the 10% remaining? this is very important to define the right material .
Let you prepare a spec sheet and submit it to vendors and corrosion specialist.
My view.
Pierre

 

[macabihaifa]

Small amounts of other components make a big difference to materials selection : water vapor content above or below dewpoint, chlorides, ammonia, CO2, etc. Most selections are made on the basis that there are trace amounts of oxygen even if component slate states there isnt any.

OK, THANKS,
CO2: 1.1 % MOL
MERCAPTANS: 5.3% MOL
H2O: 3.6 % MOL
H2S:90 % MOL

REGARDS

 

[shvet]

45 or 4.5 barg?
are you sure all components of this gas at 45 barg are in gaseous form?

 

[macabihaifa]

45 or 4.5 barg?
are you sure all components of this gas at 45 barg are in gaseous form?

forty five barg, yes it is a gas stream

 

[georgeverghese]

Will water condense at the lowest operating temp at this pressure (which may be lowest ambient temp, when there is no flow) ?

Are you sure there is no chlorides in this stream ( at concentrations > say 40ppmw or so ) ?

 

[macabihaifa]

Will water condense at the lowest operating temp at this pressure (which may be lowest ambient temp, when there is no flow) ?

Are you sure there is no chlorides in this stream ( at concentrations > say 40ppmw or so ) ?

Thank you,
the piping is insulated and there are no chlorides.

 

[georgeverghese]

Unless the piping is heat traced, at no flow, after some time, pipe contents will reach reach lowest ambient.
Take all this info to a materials selection engineer; you can read up NACE MR-01-75 guidelines also in the meanwhile.

 

[SJones]

It depends on a number of factors, not least the risk tolerance of the end user. 90% H2S at 45 bar could give rise to a major consequence. If the end user is ok with all the aspects associated with the risk management, go with carbon steel. If they cost the risk management, they might find that the lowest life cycle cost would actually come from the use of an expensive alloy, either in solid or clad form. If they are risk averse, they could just go straight for N06625 all through, and have peace of mind over the HSE aspects, if not the financial aspects.