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Thread: Question about mixing 4 inch pipe types?

  1. #1

    Unhappy Question about mixing 4 inch pipe types?

    I have some cracks and holes in my sewer line leaving my house. I have exposed the parts that need replaced and have purchased what I think I need. I have a 4" 45 degree angle, a 4" coupler, a 2 foot section of 4" pvc pipe that I will cut down to what I need, and of course pvc glue. My question is, the new parts seem to be larger then the existing parts. The old 4" pipe says Type PSM ASTM D30334. The new 4" pipe says Type 1 SCH 40 ASTM D2665. I can tell the new parts are thicker but will these pieces fit when I cut out the broken section and use the new parts. My thinking was 4" fits with 4", but I don't want to find out the new coupler won't fit tightly over the older Type PSM 4" pipe. Please help before I jump in to this project. Thanks!

  2. #2
    master plumber nimrod's Avatar
    Join Date
    Jan 2007


    the pipe you bought is schedule 40 pvc the existing pipe you have is 3034 ,sdr35 also know as thin wall sewer pipe . you can mix the two with 4'' ferncos or go buy the right pipe , you will still need the fernco to complete the repair .

  3. #3
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona

    Default s&d pipe

    A good plumbing supply store will have "bushings" for the ends of the thin pipe to increase its diameter to that of sch. 40.

  4. #4
    Commercial Plumber markts30's Avatar
    Join Date
    Sep 2006
    Phoenix, AZ


    They also make transition banded fittings for the different diameter pipes...

  5. #5
    Plumber solsacre's Avatar
    Join Date
    Nov 2006


    As long as the ID (inside diamater) is the same, and you line up the parts well it'll work great. but getting the right pipe or the proper bushings to "up size" the 3034 is better.

    as long as the s*** goes down-hill and your not making a leak or a spot to catch "stuff"............. it'll work great.

    good luck



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