Material issues with reciprocating machine piston rods
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When selecting the material for reciprocating pump piston rods, what is the difference between 38CrMoAIA and 17-4PH? Which one is more expensive?
This can only be interpreted by someone with expertise in equipment; or you can check a specialized manual for the materials, which outlines the temperature and pressure ranges suitable for using various materials
17-4PH precipitated, hardened stainless steel: it has high strength but low hardness, and is suitable for use in corrosive environments； 38CrMoALA belongs to nitrided alloy steel with surface nitriding treatment.
17-4PH is expensive, offers corrosion resistance and resistance to hydrogen sulfide
If it is to be used on the cycle hydrogen compressor in a diesel hydrogenation unit, can material 38CrMoAIA be used?
By checking the composition of the recycled hydrogen gas, if hydrogen sulfide is present and its concentration falls within the range that causes corrosion, then 17-4PH corrosion-resistant stainless steel must be used; other materials will not suffice.
In terms of price, 17-4PH is definitely more expensive; it is estimated to be 2-3 times the cost of 38CrMoAIA. . . 38CrMoAIA is a steel specifically designed for nitriding, but few new compressors are made using this material these days; the main problem is that the piston rod tends to bend during the nitriding process, and once it bends, it becomes unusable.
There is circulating hydrogen desulfurization, with hydrogen sulfide levels kept below 20 ppm