Controversy B31.3 / B31.8

[Hansito]

Dear Coleagues:

This consult is basically about a controversy regarding using B31.8 standard for NG (Natural Gas) lines upstream the meter station, that means inside de LNG plant.

We are working in a LNG (Liquefied Natural Gas) project. The applicable codes are B31.3 and B31.8.

We also have to follow the client specific documentation. One of these specific documents states "the piping after Vaporization (that means after the heat exchanging with sea water and therefore in Gas phase) should be designed according to B31.8".

The point is: Part of these mentioned piping are inside the plant, upstream the meter set assembly.

Under our opinion we should not use B31.8 for this part as B31.8 is for Gas Transmission and Distribution Piping Systems and in its paragraph 802 .12 C B31.8 sets "This code does not apply to - Piping beyond the outlet of the customer's meter set assembly".

The meaning of "Piping BEYOND the outlet of the customer's meter ...." depends on where you locate the observer, but, being B31.8 a Gas Transmission Code We understand the observer is located outside the LNG plant limits and that means to us that B31.8 it is no applicable inside.

B31.8 requires lower thickness than B31.3 and the B31.8 thickness is not enough to comply with B31.3. The pressure is constant throughout the line.

If we follow what the client documents specify, we are going to have in the same pipe track most Lines designed according to B31.3 and a few according to B31.8.

We are going to consult our client but we would appreciate to know your opinions and possible previous similar experiences.

Regards,
Hansito.

 

[BigInch]

B31.8

802.12 This code does not apply to,

ss (L) LNG systems refer to NFPA 59A and ASME B31.3

I thinks that's pretty clear.

**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[BigInch]

Do you not have a meter?

You could theoretically locate a code break at the battery limits of the LNG plant and begin B31.8 transportation after that. All piping inside the LNG plant battery limits must definately be 31.3


**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[stanweld]

In the LNG Recieving/gassification plant that we built and commissioned, only the pipe downstream of the compressor for send out and inside the plant boundary was designed and constructed to B31.8.

 

[Hansito]

Dear coleagues,

Thank you very much for your opinions.
They are really useful and valuable.

Regards,
Hansito