6% H2S pipeline

[wineackle]

What type pipe material would you recommend?
6% H2S 10,000 blpd
Pending fluid data, assuming approx.
Pressure - 600-650 psig
Temp - 100 F

 

[rneill]

normal carbon steel (up to Grade 52) complying with NACE MR0175/ISO 15156 is routinely used in this application in Western Canada. For welding, you would want to consult NACE SP0472.

Use of Grades 56 or higher may require detailed consideration of the materials properties and welding procedures.

Corrosion inhibitors would be used to mitigate general corrosion issues and a regular monitoring/inspection program would need to be established.

 

[wineackle]

What was the pipe spec for that job.
A106 gr.B smls (I think is 52,000)
Thickness?

I have heard X60 is typically used also.
Thickness?

Will be using a H2S scavenger chemical also.

 

[wineackle]

1. pressure drop/line size-
8” Sch.160, 0.906", id 6.813", 0.644 psid/100ft, 10 mile long pipeline

2. CA- question is what I need to determine. Is 0.906" wt sufficient? I am hoping someone may have an old sour gas pipeline spec for comparsion.

too bad you can't edit your own post here (after you submit).

 

[rneill]

X52 pipe has a Specified Minimum Yield Stress (SMYS) of 52,000 psi (359 MPa). A106 Grade B pipe has a SMYS of 35,000 psi (241 MPa). A106-B pipe is much weaker than X52. We do not normally use X60 pipe in western Canada for sour gas. We also often apply supplemental chemistry limits to sour service pipeline pipe (e.g., max sulfur, phosphorus, etc.).

I would recommend you consult a metallurgist if you would like to use X56 or higher. You should also consider whether you need to have pipe tested for Hydrogen Induced Cracking (HIC) resistance. Refer to NACE Report 8X194.

Thickness is calculated per your applicable design code. Whether you use a corrosion allowance or not is up to the end user. Many end users rely on corrosion inhibition, monitoring and inspection and do not apply a corrosion allowance even to sour pipelines.

As to the pipeline design, you need to consider the pipeline profile in addition to the length. PIpelines with significant elevation changes (up and down) can develop different flow regimes with slugging and other problems. In a sour gas pipeline, you want to make sure your velocities are high enough to keep liquids moving through the line. You don't want stagnant areas that could result in excessive corrosion.

 

[SJones]

Start by reviewing API 5L with a particular emphasis on Annex H and then take a look at

http://www.eng-tips.com/viewthread.cfm?qid=130588

You will note that guidance on corrosion allowance is generally beyond the capabilities of a forum such as this.

Steve Jones
Materials & Corrosion Engineer

http://www.oilandgaspeople.com/cv/11499664

http://www.linkedin.com/pub/8/83b/b04

 

[strider6]

if there is no co2 and is oxygen free then you can specify a minimal CA. if you have co2 and water then is more complicated...

S

Corrosion & Rust Prevention Control