Carbon steel to copper connection code/standard

[xixxi]

Hi everybody!
It is the most stupid situation but I need your help.

There is a chiller with copper in/out tubes and the discharge/liquid/suction piping is copper. But some 4" valves are carbon steel (pilot valve, shutoff valve). We have this kind of experience to solder CS with copper but the client is looking for a North American standard or code to make sure this connection is allowed.

[chemi-cool]

On such connection, the copper tube has to be inside the carbon steel and brazed with 30% to 40% silver.

[NH3LVR]

I have done this by boring out pipe on a lathe and using silver solder as chemi-cool suggests. However on large sizes I was able to get flanges with a copper stub already silvered to them.

[RANGER1]

Check out page 9 of link for flange adaptors.

https://www.hantempcontrols.com/uploads/5/5/2/1/55212205/hantemp_controls_condensed_catalog_and_price_list_web.pdf


Bottom of page 32 as well with HAPhillips

http://www.haphillips.com/uploads/files/VB-18E-01_MedRes.pdf