I understand I could have used a dielectric union, however the galvanlized pipe is unthreaded. I had to hack saw it of as it is the main water line to my house. I am selling my house and I don‘t want to replace the 130‘ galvanized pipe. Can I still use a dielectric union? Are the any other alternatives?
No, there's no danger of the drinking water being contaminated from this union. The only problem this will pose would be the interaction of dissimilar metals touching each other. It sets up a chemical reaction that can result in corrosion at that point. However, this takes a long time to get to a point where it could cause any problem whatsoever.
Well, if you can solder, sweat a female adapter on. Screw a 5 or 6 brass nipple into it. Join the brass nipple to the galvanize pipe with a galvanized 'slip joint coupling'. Plumbers in my area call the slip joint couplings, Moody's. Sometimes, they are called 'dresser sleeves', but that is the name of the ones that use long bolts that tightens it together. The brass nipple is a little costly, but it'll slow electrolysis, and you'll get long service out of it . You'll only get 10 years or so of service out of a dielectric union anyway. You'll get the same at least out of the procedure I explained above. I hope your galvanize line is in good enough conditon. A rental trencher and a Saturday morning, and you can have that replaced with PVC Sch.40, you know. It'd be worth it.
Why not use a portable pipe threader ? Before doing anything check with local laws and standards. Don't want to be in closing and a problem pop up !
