Pipeline internal coating 2

[Jorge Parodi]

Hello everyone!
I'm new in this community and this will be my first post yet.

1- I would like to contact somebody with experience in pipelines/ flowlines (gas from wells) with internal lining (for example: FBE, fusion bonded epoxy) for services over 800 psi, focused on connection system (suitable connection for temp – pressure range)
2- Did you experience any limitation for pigging?, Can pigging damage the coating ? Any corrosion issues ? Technical and economical advantages –disadvantages using FBE .
If any of you have comments or have had similar experiences for this, it would really help me a lot.
Thanks you

 

[SJones]

1.

You have at least 4 options for joining internally coated pipe:

a) welded with a Thru-Kote sleeve type arrangements

b) welded with a robotic crawler applied internal field joint coating

c) interference coupling as in 'positive seal coupling'

d) interference coupling such as Zap-Lok or Stealth Lock

a) is reasonably straightforward; b) is usually a disaster; c) and d) can be a good option for the right size of pipe provided that a sound qualification exercise has been performed in accordance with ISO 21329 with attention being paid to coating damage resistance

2.
Pigging can be performed with selection of appropriate pigs. Clearly, brush pigging will be a no no. Intelligent pigging can be tricky.

It's very difficult to achieve a 100% defect free coating, even after a rigorous coating and applicator qualification programme, and ensuing corrosion and leaks must be evaluated in a risk assessment taking into account the predicted corrosivity of the gas. In high criticality pipelines, some operators have been known to supplement the coating with chemical inhibition which is really pushing the lifecycle cost towards matching that of CRA-lined pipe. Some typical failures are discussed in papers such as SPE 171835 and A Husain et al, Engineering Failure Analysis, Vol 56, 2015, pp 375 - 383

Saudi Aramco are probably the greatest exponents of internal FBE coating and they have published a number of papers.


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.

 

[BigInch]

FSU countries love internal FBE even more than SA, where it is used extensively on gas transmission pipelines where the smoother surface helps reduce friction as well.

 

[LittleInch]

First you need to work out why you want an internal coating?

Reading your OP carefully it seems to imply wet gas from wellheads and hence maybe corrosion issues?

The base problem, as S Jones excellently puts it, as always, is that the jointing is an issue and it's very difficult / practically impossible to
a) get 100% quality / coverage in the beginning or
b) inspect it in service and fix any defects in the coating

Given that with the coating you're probably trying to save money by using Carbon steel instead of Stl Stl or Duplex, it won't take very long before your small coating defect eats its way through the pipe wall.

Using internal coatings for flowlines is not common as the saving in pressure drop is very small due to short lines compared to the cost.

For long distance dry gas lines, internal or sometimes called flow coating is a well known use which has many benefits which pay back very quickly. Normally they don't bother coating the weld area, but accept that a 95%+ coverage does the job.

Pigging limitation - can only use "soft" pigs for operational pigging, so no brushes and some intelligent pigs can find internal coatings difficult, but lots of lines have been pigged with internal coatings so just need to let the pigging company know up front.

Plus points - less pressure drop
Negative - costs money, joints can be a big issue, not really qualified for internal corrosion protection.




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

 

[dik]

Does a break in the coating cause greater anodic corrosion at the joint?

Dik

 

[SJones]

@dik - Good question. Initially, the corrosion rate will tend to that of bare carbon steel since the exposed carbon steel will not be solely an anodic site. However, should a pit develop as a result of the localised exposure, it is feasible that corrosion rates within the pit could be exacerbated.

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.