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  1. OGMetEngr

    Solution Annealing Hot Forged Fasteners

    CoryPad is correct, I saw this at my last job. Suppliers were giving us process-annealed barstock. The bar ASTM allows this, but others such as sheet do not. We had 13.6N HNO3 which requires fully solution annealed material for adequate corrosion resistance. The process-annealed bar would...
  2. OGMetEngr

    AISI 4140 80K MYS

    Well that's a wide open question. The strength will derate as temperature increases. In general, staying 100F below the temper temperature will maintain strength unless extended times are seen. Take a look at the Holloman-Jaffe parameter and equate the temperature/time used for the temper...
  3. OGMetEngr

    Non-wetted parts NACE requirements

    1) If those parts have the potential to be "exposed" to sour fluid in the event of a leak (e.g. - embedded under insulation), then the bolting should also be NACE compliant. 2) See answer to #1. You don't want a minor leak to turn into a major one. 3) Materials oftentimes have internal stresses...
  4. OGMetEngr

    SDSS MONOFLANGE VALVES FOR DSS PIPING

    Not knowing your operating conditions I can only speak to the material differences. It could be that a more crevice-corrosion resistant material (SDSS) is wanted for the flange (crevice is present), while DSS is suitable for the piping (no/less crevices).
  5. OGMetEngr

    Cladding vs Overlay for Sour Service

    The short answer is yes, the parent material must be NACE compliant. The overlay HAZ, which is also within the parent material, must comply as well. As SJones pointed out, there is a clause that allows one to use their "documented" reliability of the overlay to use parent material that doesn't...
  6. OGMetEngr

    Cladding vs Overlay for Sour Service

    1) Yes (according to NACE MR0175). Also the weld/overlay HAZ must comply with the standard. 2) This is question 1 reworded. Still a yes. The reason is in case the cladding or lining integrity is compromised, you don't want your base metal cracking.
  7. OGMetEngr

    SSC, SZC, SOHIC- ISO15156-2

    I agree that this clause leaves much to be desired on the subject. A majority of the standard reads like a group of metallurgists and lawyers were locked in a room and required to come up with something before they were allowed to leave. Also as I'm sure you're aware, if you don't know the...
  8. OGMetEngr

    SSC, SZC, SOHIC- ISO15156-2

    1) Each mechanisms needs to be addressed separately. That being said, Section 2 clause 7 gives requirements in order to be resistant to all three (SSC, SOHIC, and SZC). SZC/SOHIC involves looking at unfailed SSC specimens after testing looking for indications of SZC/SOHIC. 2) For HIC/SWC...
  9. OGMetEngr

    Problems on Material Requirements for HB,HIC,SOHIC Damage in Wet H2S Service

    First take a look at NACE MR0175/ISO15156 Part 2 Clause 8. If HIC/SWC is a concern after reading this, then it will direct you to Annex B Clause B.5 and Table B.3 to test for susceptibility using the already mentioned TM0284. You'll notice that is directs you to "consider" this and that. This...
  10. OGMetEngr

    Cathodic Protection

    I forgot to mention, this is assuming a close to neutral pH for your fluid. A different pH will be a different story.
  11. OGMetEngr

    Cathodic Protection

    If you're trying to protect steel, stainless, and similar with a passive CP system then an AlZnIn anode may be suitable. This will polarize the material down to around -1.1 V, you'll just want to speak with an anode manufacturer to be sure you won't have any passive layers that may set up on...
  12. OGMetEngr

    Flame Cutting of Rolled and Welded NACE cylinders

    I'm not sure what exactly a "NACE cylinder" is, or which NACE standard you refer to, but I'll give it a try. MR0175 requires NACE compliant material to be in an approved heat treat condition, as well as meeting all other requirements in the document. Approved HT conditions are: Hot-rolled...
  13. OGMetEngr

    A240 vs A276/A479

    Also, it may or may not matter in your case, but A276/A479 both reference A484 for annealing which allows the use of hot rolling to be counted as the "in-process anneal". A240 instead references A480 which requires a separate solution anneal process. I've seen the results of this first-hand...
  14. OGMetEngr

    Susceptible to intensified corrosion? - welding 316 SS to Carbon Steel (ASTM A36, A572 Gr. 50)

    I would recommend a welded connection for CP continuity over a bolted solution. The carbon steel / stainless steel materials, including the weld, will all be polarized by the anode and protected. A bolted union only invites the potential for a break in the circuit, among other things, and will...
  15. OGMetEngr

    Cathodic Protection

    What is the fluid? Material to be protected? Sacrificial material? Suitability will depend on the electrochemical potential of both the cathode (to be protected) as well as the anode in the environment of interest, as well as the polarization characteristics, geometry, and more...
  16. OGMetEngr

    welding in the material of fork in forlift

    29 CFR 1910.178(a)(2) requires that powered industrial trucks meet the design and construction requirements established in ANSI B56.1 - 1969. ANSI B56.1 section 419.B then requires of the manufacturer: The factor of safety of forks shall be at least 3 to 1 based on the yield point of the...
  17. OGMetEngr

    17-4 PH SS material for valve stem

    17-4 has been used often for stems, they have also failed often. I wouldn't recommend welding 17-4 either. Depending on other factors, a CRA would probably be a better choice if high strength, NACE compliance, and localized corrosion resistance is needed. 17-4 has pitting/crevice corrosion...
  18. OGMetEngr

    Inconel 718 or 750

    It depends entirely upon application which alloy is better. NACE MR0175 allows X750 up to 50HRC for springs, whereas alloy 718 is never allowed above 40HRC in sour service. If you have a spring needing the highest strength and fatigue life, X750 may be better. As others have stated, 718 will...
  19. OGMetEngr

    Cracked 4340 after quench

    I'd recommend polymer over oil, as they make various polymer types that are good replacements for the cooling rate you get during oil quenching. This without the fire hazard and HSE concerns. Just make sure to analyze your polymer bath regularly to ensure it hasn't degraded.
  20. OGMetEngr

    Cracked 4340 after quench

    4340 is quite susceptible to cracking when quenching in water. This is due to the very high hardenability which causes a severe volume change gradient going from austenite to martensite through the thickness. Also, delayed quench cracking if not immediately tempered after quenching occurs with...

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