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Replacing corroded class 250 or 300 black/malleable iron pipe & elbow on WGO-4 series 3

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masscat
masscat Member Posts: 14
edited May 6 in Oil Heating

Hi all, I need to replace, what appears to be, a heavily corroded class 250 or 300 malleable iron elbow and section of 4ft, 1-1/4" black pipe near the return of my Weil-McClain P-WGO-4 series 3.

  1. Can I use class 150 fittings/pipe? I can't easily find class 250 or 300. The manual doesn't seem to specify. Looking at an Anvil cut sheet suggests I can go up to a temp of 250F at 225PSI with class 150 fittings. The max temp I've observed on my heat gun exiting the boiler is ~190F, but I know the boiler is firing above 370F.
  2. The manual suggests front section B1 return piping has a 1-1/2" pipe size. My system looks like it immediately reduces to 1-1/4" at the return with a bushing (all the pipes measure 5-3/8" circumference…~1.71" diameter.
  3. I'm getting some used Ridgid tools (die head, ratchet, reamer, 3-wheel cutter, pipe stand). I'll have a retired machinist (dad) who installed/maintained his own boiler helping, but he prefer sawzall and hasn't done this in years.
  4. Any watchouts for draining the system?

See images below.

Corrosion-1.jpg Corrosion-2.jpg Corrosion-3.jpg

Comments

  • pecmsg
    pecmsg Member Posts: 7,270
    edited May 6

    those look like schedule 80 fittings. There used on high pressure systems.
    I don’t think you need something that heavy on a domestic boiler.
    I hope there’s a union nearby!

  • mattmia2
    mattmia2 Member Posts: 17,416

    if this is hot water you can replace it with pretty much any black fittings and pipe or you could also replace it with copper.

  • masscat
    masscat Member Posts: 14
    https://forum.heatinghelp.com/discussion/comment/1895944#Comment_1895944

    Baseboard heat. Indirect HW is on the other side.

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,461

    You can certainly use 150# malleable or 125# CI fittings. They are the same dimensions as the 250 or 300# fittings.

    As mentioned above copper is a good choice as well

  • hot_rod
    hot_rod Member Posts: 27,806

    a sawzall, handheld power threader, union and some new fittings is the fix.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • JUGHNE
    JUGHNE Member Posts: 11,603

    Can you explain the firing above 370 degrees??

  • mattmia2
    mattmia2 Member Posts: 17,416
    https://forum.heatinghelp.com/discussion/comment/1896018#Comment_1896018

    i think they mean stack temp.

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 12,492

    Those fittings look like Cast Iron fittings, not malleable. You should use the standard malleable fittings in that location.

    Either will work for you. The boiler pressure should not exceed 30 PSI if the relief valve is operating properly. The flame temperature may exceed 2,000°F; however, the water temperature should not exceed 240°F if the limit control is functioning correctly. I would not set it that high, though. A 180°F setting is usually adequate, so the water temperature should normally stay below that.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    masscat
  • masscat
    masscat Member Posts: 14
    https://forum.heatinghelp.com/discussion/comment/1896018#Comment_1896018

    I have a heat gun picking up the flame temp. I wasn’t sure what the fittings needed to be rated for. Boiler temp is set for 180F

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