On my current project, a refinery revamp job, we're using Cr Mo 1.25%, 5% and 9%. We're purging for the CrMo 5% and 9% as in addition to ASME B31.3 and ASME IX, our Client requires us to follow, API 582, Welding Guidelines for the Chemical, Oil and Gas Industries. In API 582, Clause 7.3 states that back purging is required for welding materials having a nominal chromium content greater than 2.25%. For purging gas, we're planning to use nitrogen.
We're getting ready to run some A336, F22 PQR's here; GTAW root & hot, SMAW remainder. This is for High Pressure ASME B31.3 stuff. Our intent is to run the PQR WITHOUT purge but to use purge during production.
This is some very costly, highly critical stuff and although not "technically required" to use a purge, as Welding Engineer for our project it makes good engineering sense to me.
Okay, so we pay just a fraction more, but hold one more ace up our sleeves to help ensure our success.
By 3.1 Inspector
Date 06-30-2008 07:13
I knew it was written somewhere :)
Is nitrogen cheaper than argon?
Have you qualified your WPS with nitrogen - as most codes has gas composition as an essential.
3.1
QW-408.8 addresses the deletion of purge but not the addition so if one qualifies without a purge one can add purge without requalification. In addition, in my case we're using a P5A so the variable doesn't even apply. For project, our specifications do not allow nitrogen purge and yes, nitrogen is typically lest costly than argon but we'll use argon anyway because it's not worth tryinig to get specification concession. ASME QW-256 doesn't address gas composition for purge, only for shielding.
Hence, in my own case, there are things one does because they simply make good sense and others we do because code mandates.
API 582 is a RP. A guideline not a mandated code requirement. Sorry 3.1. Note: As we celerbrate our nations founding lets remember the men and women that have given everything to make this a great country.
God Bless the USA
Jim
By 3.1 Inspector
Date 07-05-2008 05:25
I know what API 582 is...
Hope you had a nice 4th of July