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Recommended material for a piston rod

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  • Recommended material for a piston rod



    Above is a picture of a piston rod from a triplex mud pump. The rough dimensions are 75 mm OD and 350 mm long. I need to make nine more for spares. Can anyone recommend a suitable material to fabricate them?

    Thanks,

    Barty

  • #2
    Personally I would use 4140. Possibly heat treat the parts that rub.
    Andy

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    • #3
      does it see water or anything corrosive ?

      Im with Andy unless rust is an issue then id go with something like 17-4 H900

      Comment


      • #4
        Thanks for the replies gentlemen.

        The rod is exposed to water. Water is used to cool the rear of the piston and liner. We normally run soluble oil with the water to aid with lubrication. With this in mind would 4140 still be suitable?

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        • #5
          Saying that you "need to make nine more as spares" suggests regular failures. How do the rods fail? That will influence the choice of material.

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          • #6
            Originally posted by jlevie View Post
            Saying that you "need to make nine more as spares" suggests regular failures. How do the rods fail? That will influence the choice of material.
            No they are not failing. I need the extra piston rods so that we can change the pump liners and pistons quickly. If we have to change out a set of liners, we pre setup one set of liners with pistons and the piston rod and change them out as a set. This cuts the change out time significantly.

            We have three triplex pumps and therefore need nine piston rods.

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            • #7
              Gottcha. Probably most any of the 4000 series steels would be suitable with 4130 & 4140 being good choices. I don't know enough about the pump to say whether they should be heat treated. Given the environment, plating for corrosion and abrasion resistance might be advisable, though it doesn't look like the originals are plated.

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              • #8
                If'n that upper R/H corner of your pic is a keyboard and the scale is true, your mud pump ain't the type/size of mud pumps we're familiar with. Are you referring to wet cement slurry mix as your 'mud'? It is abraisive as all get out, but should never come in contact with that rod.

                4140 is about as good a shot as you can take. We would be interested in a quick sketch of the pump
                motions, re. piston/plunger dimension(s), connecting rod, crosshead/shoe and crankshaft/stroke.

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                • #9
                  I'd think, in addition to the choices already mentioned, P20 would probably be a good choice as would VascoMax.
                  James Kilroy

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                  • #10
                    Originally posted by jlevie View Post
                    Gottcha. Probably most any of the 4000 series steels would be suitable with 4130 & 4140 being good choices.
                    4130? Are you sure about that?

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                    • #11
                      Originally posted by Royldean View Post
                      4130? Are you sure about that?
                      Well, the important difference between the two is that 4140 has a bit more carbon and manganese and thus can be heat treated to a greater hardness. Either can be case hardened nicely. It isn't clear to me whether it would be best to harden the entire piece or just surface harden the wear points since the rod will see a cyclic load. Some ductility in the rod might be a good thing.

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                      • #12
                        Is the one shown available for destructive testing? Check how hard it is.

                        And yeah, what are you pumping? Concrete? Drilling mud?

                        Finest regards,

                        doug

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                        • #13
                          Originally posted by michigan doug View Post
                          Is the one shown available for destructive testing? Check how hard it is.

                          And yeah, what are you pumping? Concrete? Drilling mud?

                          Finest regards,

                          doug
                          We could use the one shown for destructive testing.

                          We are pumping drilling mud.

                          Barty
                          Last edited by Barty; 11-28-2013, 12:30 PM.

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                          • #14
                            Originally posted by Barty View Post
                            We could use the one shown for destructive testing.

                            We are pump drilling mud.

                            Barty
                            I wouldn't imagine that you would have to harden the pump rods very much.

                            Bentonite is about as abrasive as toothpaste. As a matter of fact the alternative (natural lifestyle) folks even recommend that it be used to substitute for the harmful chemical toothpastes.

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                            • #15
                              If they are important enough to make 9 of them it would seem worth the effort to find out what the sample is made of and a hardness check. With a proper lab they should be able to do both without sectioning the part. In the US it costs about $150.and takes just a few days. Probably take longer than that to get the right material and machine heat treat so would be cheap insurance. Then if you need to upgrade the material grade for toughness or wear you know where you are starting from and then material suggestions could be made If you can a manufactures print then you could get grade and heat treat info off of that. Sometimes grades can be pulled from the websites as well.

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