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Sour Pipeline Depressurizing

pipeline sour depressurizing

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#1 Ghasem.Bashiri


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Posted 10 September 2021 - 08:09 AM

Dear Experts

I exposed with design of some sour pipeline in remote area (unmanned).

The pipelines are underground due to safety limitation (0.6 to 20 wt.% H2S).

Our concern is that what should be safe and standard design for depressurizing.

It is obvious that quick (e.g. 15 min) depressurizing is not practical for pipeline.

However, long depressurizing (e.g. 10-40 hr) may not have any benefit during issues such as pipeline rupture.

Some safety engineer told me pipeline rupture is a low frequency accident and should be ignored for pipeline flare design (depressurizing).

Finally which type of flare we should use as it is not automatic.

Some designer proposed flare with gun and small sterile area. However, it is not clear procedure for opening of inlet line to flare

and also ignition of flare after opening.

I search most international code and standards and there is not any written procedure and policy for such design.


#2 Pilesar


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Posted 11 September 2021 - 09:19 AM

Pipeline flares are typically not designed for emergency depressurization. When pipelines are depressured for maintenance, long depressuring is normal. Pit flares and temporary flares usually do the job. The quantity of H2S in your pipeline requires special consideration as breathing it is a killer. The pipeline owner must have a plan to deal with the hydrogen sulfide. I have worked with pipelines containing about 2% H2S but did not investigate their flaring enough to help you. I would not want to design for flaring this stuff without finding someone else with experience to be legally responsible. I would hope the flaring of lethal gas would have even more safeguards than for regular flammable gas. H2S scares me.

#3 breizh


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Posted 11 September 2021 - 06:48 PM


Pilesar is totally right , H2S is a dangerous chemical !!! I've attached a document about concentration in air and consequences :


It could lead to fatality and explosion .



You should consult senior managers within your organization and people in charge of safety . 


You may get advices from Vendor using the link underneath:




Good luck


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