JessCalizar,
Check the legends and abbreviations section if there is one for your P&IDs. That should list how the piping specs are called out. From there, you should be able to get the pipe schedule from the piping specs. For example, the company I work for uses piping notation like 2" HPS-E1-HC where the 2" is line size, HPS means high pressure (200 PSI) steam, E1 is the piping spec class, which according to the legends and abbreviations is 300# RF rating in carbon steel, and the HC means the pipe is insulated for heat conservation. From my piping specifications (from the maintenance supervisor, and also the corporate website), the E1 specification refers to PIP PN03CS1S02, which correlates to STD (sched 40) pipe for a 2" line. If the line had been 1", it should be XS (sched 80) per the standard. Check with your maintenance group, mechanical integrity engineer, or corporate engineering to see what piping specs you use and also for the abbreviation list for your P&IDs. Hope this helps.
Regards,
Matt
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