Hello, I'm currently performing piping stress analysis for LNG Tank terminal.
And we should comply with NFPA-59A(2013) for Seismic design.

NFPA-59A specify as below,

9.2.2.1. For purpose of design, all piping of the LNG facility shall be classified into on of the following three seismic categories:

[b](1) Category I - All piping supported by the LNG container and piping up to the emergency shutdown valve(s) and firewater piping

(2) Category II - All flammable gas or LNG process piping.

(3) Category III - All other piping not included in Categories I and II

9.2.2.2. Piping categories shall be in accordance with the following

(1) Category I - All Category I piping shall be designed for the OBE and SSE event. For the OBE design, response modifications shall no be used.

(2) Category II.........[i][/i]

Here, my question is...

1. The firewater piping described in above Category I means all of the fire water lines for the LNG Terminal? or only means the fire water line on the LNG tank?

2. According to NFPA, the lies belong to Category II,III should also designed for seismic. Then, all pipe lines in the LNG facility are subjected to the piping stress analysis with CAESAR-II?

I looking forward to someone's comments.
Thank

For 1 - I'll answer in the form of a question. In event of a fire (before, during, or after an earthquake), would a leak anywhere in your firewater piping system(s) compromise the safety of the LNG system?

For 2 - What does NFPA say passes for seismic design? I'll note that B31.3 permits forgoing analysis on piping on the basis of similarity. It would be the user's discretion as to which case is the worst case, however. (This doesn't mean that B31.3 is your piping code, of course.)

1. Literally the clause does not mean the LNG tank only ...
2. The scope of lines subject to CAESAR II might depend on the requirements from the Owner, or the analyst's discretion (subsequently the contents written in Pipe Stress Specification of project).
Considering the criticality of LNG facilities, I recommend that all cryogenic lines be analysed, better by means of CAESAR II. (For the small-sized, a simple modelling and running can be carried out for your judgement if a formal report is not required).