Advantages of B31.9 vs 31.3?

[FixerTed]

For systems under 150psig, is there an economic or practical advantage to using ANSI spec 31.9 instead of 31.3? Seems like most fabrication and construction people are more familiar with 31.3 but with my 130psig system 31.9 would apply.
Thanks,

 

[BigInch]

B31.3 is for design of chemical and petroleum plants and refineries processing chemicals and hydrocarbons, water and steam. This Code contains rules for piping typically found in petroleum refineries; chemical, pharmaceutical, textile, paper, semiconductor, and cryogenic plants; and related processing plants and terminals.

B31.9 has rules for the piping in industrial, institutional, commercial and public buildings, and multi-unit residences.

Are you having trouble telling the difference between commercial, public, residence, instutional buildings and chemical, refinery, or petroleum plants? If nothing else, your nose should be able to give you some pretty good clues.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[mfoote]

My two cents (if it's worth that much ):

Where I work, we generally design all piping to 31.1. In some cases 31.9 is actually a more applicable code (based on temp & pressure).

We could state on our design drawings that the piping is designed to 31.9 or 31.1 and I suspect our projects will still cost the same. The reason being that we generally don't weaken our specs regardless of what piping code is most applicable - i.e. we still call for a minimum of 10% radiography regardless of the temp & pressure. We keep the same specs regardless of temp & pressure because we have very little tolerance for failure so we demand a higher quality installation.

I guess in the end, what I'm getting at is if you decide to go with 31.9 instead of 31.3, you'd have to make sure that the QA/QC requirements are properly adjusted to refelect the actual code that your using. In my limited experience, it's the QA/QC requirements that really cost you on a project.

Cheers

 

[BigInch]

I would have thought it was the pipe and equipment that cost the most, unless you're talking about a lack of QA/QC.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[mfoote]

Sorry, when I said it's the QA/QC requirements that really cost you, I mean in a relative sense. From jobs that I've worked on the additional QA/QC requirements to execute 31.1/.3 work is where the bulk of the cost difference occurs between a 31.1/.3 and 31.9 project.

As an example, where I'm from a lot of contractor's quality management system require MTR's for all materials when fabricating to 31.1 or 31.3. They don't hold the same requirement for 31.9 piping. Vendors will charge you extra to provide this documentation. This is just one example of the additional costs.

Cheers

 

[BigInch]

Didn't cross my mind that you wouldn't ask for MTRs for B31.9 work.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus