Annealing Oven Hydrogen Purge

[summerf]

I am installing an oven that uses Hydrogen as the cover gas and the design has a hydrogen purge after burner on the unit which would be inside the plant (the manufacturer is a Japanese company with no experience fabricating equipment for the US). I seem to recall in a plant I worked at several years ago had annealing ovens that had a hydrogen burner right on the vent which was inside the building. Then it was exhaust outside the plant thru a duct. However, I cannot find any source that indicates a hydrogen purge vent burner can be install inside a building. Can anyone provide me some insight?

 

[AidanMc]

I do not know about hydrogen specifically but our atmosphere furnaces (nitrogen/methanol/propane blend) have pilot flames at the exhaust areas going up into exhaust venting to the outside. We have a number of furnaces with this design in our facility.

Perhaps NFPA 86 would have the answer to your question.

Aidan McAllister
Metallurgical Engineer

 

[EdStainless]

All of our furnaces vent inside the buildings, with pilot lights to assure burn off.
Our plants in mild climates have vent hood over them, but in the north we don't even bother with that.
Some of these are new installations and comply with all current codes.

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P.E. Metallurgy, Plymouth Tube

 

[summerf]

EdStainless, Your cover gas is Hydrogen? Do you know the standard that states this method is acceptable? My manager wants documentation that states it is acceptable.

 

[EdStainless]

Well I would start with NFPA (sorry, I don't remember which specific code section), since many of the things that we do with hydrogen furnaces are governed there.
Depending on which plant (we bright anneal in 3 locations) we have 2400-4000 scfm of hydrogen flow, with it all vented indoors via burn-off.
We want to run ours at low temps (1200F) so we needed to modify the interlock logic to allow us to purge, heat to over 1500F, introduce hydrogen, and then reduce temperature.

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P.E. Metallurgy, Plymouth Tube

 

[berkshire]

In the past I have constructed several collection hoods over hydrogen vents, these all had pilot lights to ensure venting gas was flared off. The burnt gas was then vented out of the building via a fluepipe from the collection hood. Since these were done in several locations I do not know which codes they were constructed to.
B.E.

You are judged not by what you know, but by what you can do.