I've tried doing exactly that (although admittedly not very extensively), and I've come across a pattern: vendors that supply both gear operated and handwheel/bar/lever operated valves in a wide and interlapping size range, and give tables of opening/closing torques with no direct indication of...
Thanks for the insight, LittleInch.
I asked and care because the piping specs the firm I work for issues specify size ranges for the type of actuator (I'm not sure if this is the norm in other countries/firms?). Gearboxes are specified for 10" and up for 150 PSI butterfly valves, 6" for class...
Hello, LittleInch,
Exactly, it's all about opening and closing torques. But I've never seen anyone actually calculate torque requirements for a manual valve when assembling a piping specification. When I'm doing so, I just follow what was specified in previous projects.
So I guess I'm asking...
Hello all,
Does anyone know of specific guidelines/standards/documented best practices that specify the largest diameter a valve of a given class and type should go without a gear operator? Vendors' catalogues show that many supply valves with gear operators from 2" and up, though I haven't...
Dear all,
I've been tasked with reviewing the piping materials specification for a gold plant project that calls for HDPE pipe for the following substances, all at ambient temperature, though exposed to the sun in a tropical area:
- 20% w/v sodium cyanide solution
- 33% w/v hydrochloric acid...
Dear all,
When used within the pressure-temperature rating given by an applicable standard, such as MSS SP-70, is there a code related reason for most gate valves to be specified in carbon steel instead of cheaper gray iron? I looked through ASME B31.3 and found only this paragraph related to...
The vast majority of projects are of plants - chemical, fertilizer, oil and gas, ethanol, cogeneration, mining, tank terminals. There are some pipeline projects, but those are fewer and usually involve a greater deal of experienced professionals.
We work with carbon, stainless, duplex, and...
I posted this under the piping engineering forum, but I'm not sure if this forum isn't more suitable, as this post focuses on piping materials.
I'm a young engineer with a little over three years of working experience as a piping materials engineer. Right now I'm feeling overwhelmed...
I'm a young engineer with a little over three years of working experience as a piping materials engineer. Right now I'm feeling overwhelmed.
Engineering as a whole in my country was heavily impacted by some events in the recent past, and most of the seasoned engineers either switched fields...
@LittleInch, the client requested welded tubing and tubing fittings with gas service. They had a bad previous experience with leaky compression fittings and decided on welded tubing, to minimize the chance of in-service leakage.
@1503-44, absolutely. Stress-wise the lighter gauges are more than enough for my low-pressure gas service application. I'm asking specifically about the recommended minimum wall thickness for gas service, which is another consideration.
Hello,
Many tubing manufacturers recommend a minimum wall thickness for tubing used in gas service. The reasoning behind that is that a heavier wall has a greater capacity to resist ferrule actions and coin out defects that might enable a leak path for gas molecules (for example, Swagelok's...
@ironic_metallurgist, that's the thing... A928 pipe is welded with filler metal, but the standard still calls for heat treatment, unless the purchaser specifically requests that none be carried out. ASTM A815 allows for fittings welded with the addition of filler metal, and indiscriminately...
For some reason I had it in my mind that I had checked the compositions of E2594/ER2594 against UNS S32750 and seen them to be the same. I don't know how I arrived at that conclusion. That one is on me, thank you for pointing the higher nickel content. Why though does A928 list UNS S32750 as the...
Hello, everyone!
I'm sorry I didn't get back to this soon enough. Picking up where we left, I'd like to press on a little longer.
The filler having a different composition which obviates heat treatment post-welding makes sense. However, ASTM A928 specifies E2594/ER2594 consumables for welding...
Thank you all for your various inputs on this matter.
SnTMan, A790 establishes very similar minimum temperatures and rapid cooling for the heat treatment of those grades of DSS. I gather that the PWHT mentioned in B31.3 for DSS is in fact the full anneal required by these material...
You mean a sub-critical heat treatment is not advisable for stainless steels in general, including duplex alloys, whereas a full anneal would be (being the only applicable one)?
As to the pipe the vendor is offering to furnish, if it won't be heat treated, it must pass tests per A923, as stated...
Thank you for your responses.
@ironic_metallurgist, is that to say that heat treatments performed at a higher temperature than that usually associated with PWHT stress relief are acceptable?
I am still in doubt about this issue:
ASME B31.3 has this to say about requirements for postweld heat...
Hello, all,
I've read around these forums and have come across a seeminlgy consistent opinion that post-weld heat treatment is not a recommended pratice for duplex stainless steels on account of the possible formation of a deleterious phase in the material.
What is making me uneasy about this...
