Brass vs Stainless Steel vs Black Iron fittings into Boiler Castings

PoponPachaug

Can anyone speak about the advantages or problems with the choices of either Black Iron, Heavy Black Iron, Stainless Steel or Brass fittings into the Boiler Castings?

pecmsg

Nothing wrong with black pipe!
why waste money on brass or stainless?

MikeAmann

https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=merit brass stainless

These stainless fittings might be a little more expensive, but I am very impressed with the quality.
The threads are actually as clean (smooth) as the pictures show. And they never rust.
I used them everywhere that I could on my system.

hot_rod

A couple that couple things to be aware of when mixing metals. The galvanic  reaction between mixed metals leading to corrosion.
Also water quality, the austenitic stainless grades don’t do well with high chlorine or chlorides. High temperature condition add to the potential of corrosion.
Might be better with steel nipples into a boiler, steam especially.

retiredguy

Years ago, I tried replacing a few steel nipples in a boiler's return piping with stainless nipples since I thought that they would last indefinitely but I was wrong. They lasted less than a year, so I was back to using all sch 80 (x-hvy) on all return piping, below the water line. For the younger guys, Just for your information, a lot of the steam and return piping used before the 1950's was wrought iron and not steel which lasted a very long time. When the wrought iron piping was replaced with sch 40 steel piping it didn't last very long, so that is why I always used sch80 below the water line.

One horror story; A very cheap customer for a hotel near the Pittsburgh Intl Airport needed the pumped condensate lines replaced. I recommended using sch 80 piping. He wanted to know the cost difference between sch 40 and sch 80. I told him that the sch 40 would not last very long but he insisted on the sch 40, to save a few $$. months later, that condensate pump piping was leaking and deteriorated and again needed replaced. He wanted a free re-pipe claiming a warranty which he did not get. He then called another company who again replaced the piping with sch 40. We were called back about 6 months later to replace the piping with sch 80.

MikeAmann

hot_rod said:

A couple that couple things to be aware of when mixing metals. The galvanic  reaction between mixed metals leading to corrosion.
Also water quality, the austenitic stainless grades don’t do well with high chlorine or chlorides. High temperature condition add to the potential of corrosion.
Might be better with steel nipples into a boiler, steam especially.

From that chart I see that zinc and aluminum have the lowest numbers.
Can I conclude from that that this is why these metals are chosen for sacrificial anodes?

Larry Weingarten

Hi @MikeAmann , Yes! Add magnesium to the list and you have the most common sacrificial anode metals. Metallic sodium is right in there too, but it blows up in water. It's a bit too reactive

Yours, Larry

MikeAmann

Magnesium, that's the 3rd metal missing from that list. Thanks.

PoponPachaug

Thank you gentlemen for your responses!!