Bypass w/globe valve at steam PRV - not allowed?

incompressibleflow

I recently watched a video that was posted on the Heating Help account about PRVs in Steam Heating Systems, and Dan said 'in New York City you aren't allowed to run bypasses around PRVs - if you have to shut the steam down, you have to shut the steam down.'

Is that correct? Under what circumstances is the bypass allowed or not allowed? Is it codified anywhere?

You can hear it here at the 2:04 mark:
https://www.youtube.com/watch?v=uI6TTrqfQ3A&t=124s

Jamie Hall

I can't speak to code. I can speak to common sense, though. If somehow you managed to get high pressure steam over on the low pressure side, you have a real safety hazard. Many of the devices on low pressure steam are only rated to 15 or sometimes 30 psi, including vents, and they will fail. If they fail, it's almost always going to be open -- and you get 200 psi steam at around 380 F. This will kill you remarkably fast...

pecmsg

It’s been a lot of years since I worked in the city but all PRV’s had bypasses to slowly pressurize down stream. 

bburd

"To be operated by a trained professional. Do not try this at home!" 😳

EBEBRATT-Ed

All the steam PRVs i have seen or have installed had a bypass......and a low pressure relief valve downstream.

Many of these are used for heating, also hospitals, or for process that have to be able to run.

But NYC has it's own rules I guess