Insulating flange kit

[qualitypro]

We are putting a low pressure fuel gas line in a power project that has sections of underground to aboveground and back to underground piping. Do we need insulating flange kit at these UG & AG locations mandatorily? Is there a ASME or other Code requirement that specifies this? Appreciate your inputs.

 

[SJones]

Is cathodic protection to be applied to the buried sections? Guidance on whether to isolate is given in NACE SP0169. The problem with station piping is that isolation tends to get shorted by earthing and instrumentation.

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.

 

[LittleInch]

There are no code requirments, but as S Jones says, if you don't electically isolate your A/G sections if the U/G sections are cathodically protected, then the U/G section will end up with no CP on them as the voltage and current leak away either via earthing connections, supports or earthed instruments. CP voltage can also be a hazard above ground for bare metal creating shock and spark potential.

You need to determine if Cp is actually required or just make it quite thick ( if it's low pressure it probably is much thicker than it needs to be for the pressure alone) and coat and wrap it.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[qualitypro]

Thanks to SJones & Liitleinch for your responses. I have some more info that I would like to share with you. The short section of above ground piping has no earthing connections but just a flanged valve. Is the insulating kit still needed as there is no earthing? The engineer has provided details for providing insulating kit at the A/G valve flanges. Is this an acceptable practice?

 

[LittleInch]

It's not freeway, but will prevent an operator getting a shock. If you have any supports they need to be insulated, normally by using clamp support with insulating material between the pipe and the clamp.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[LittleInch]

Should read it's not great... Damn predictive text.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[SJones]

qualitypro - you haven't answered the cathodic protection question. In addition, is the valve of a different material? Trying to puzzle out why isolation is actually required.

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.

 

[sentjoh]

And if flanges or -pairs are insulated, do they need to be equipped with some kind of leak detection? What kind of insulation material is required?

Regards,

Johan Sentjens

http://www.linkedin.com/in/johansentjens

 

[qualitypro]

Sjones, There is CP provided in the underground section if this answers your question. The Engineer has specified Insulating Flange kit at the valve. The valve is carbon steel just as the piping.

 

[SJones]

Consult NACE SP0169 and NACE SP0286.

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.