Onshore Buried Pipeline having two Material of construction

[phyt86]

onshore Pipe line, that will be carrying Gas +Condensate well fluid from an on shore well pad to the Gas oil separation plant. The length of pipe line is approx. 40 km. underground portion of which is made of sour rated and externally 3 LPE coated carbon Steel . Above ground portion of the pipe line where the well pad is connected is made of SS 316 L and is externally hot insulated. Well fluid (gas + condensate)carries H2S of 6 to 8 Mole %, CO2 of 10 mole % and water of approx. 25 mole %. Temperature of well fluid is around 80 deg C and pressure = 100 bar. The Chloride level in the produced (formation) water is around 150,000 ppm.

i am evaluating this study for its damage mechanism. list of damage mechanism that susceptible for this study are :
1)H2S cracking
2)HIC
3)CL SCC
4)Corrosion Erosion

my suggestion are as follow :
for buried pipeline - to change its material to super duplex material n control its CP to -850mV to -450mV.

any comments on the study?

 

[SJones]

1. Review ISO 15156-3 and work out how you plan to get 316L and duplex SS into the frame with that amount of H2S and chloride
2. Create a degradation mechanism checklist from API RP 571 and the Energy Institute Guidance For Corrosion Management and add in 'long running ductile fracture'
3. Have a go at life cycle costing the options

Steve Jones
Corrosion Management Consultant

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

All answers are personal opinions only and are in no way connected with any employer.

 

[brimmer]

40 km of super duplex, sounds expensive.... Have a look at how other operating companies (or regions) operate similar pipelines to what you have.