As part of a life extension study I'm completing a creep assessment in accordance with Part 10 of API 579 and following the Omega using isochronous curve method. The material is 5Cr-0.5Mo.
I have a few questions on two points if anybody is able to help. Thanks.
1. Triaxiality Parameter
I...
From my records B36.19 has never been in Table U-3 but I don't think Table U-3 is intended to be an exhaustive list of all acceptable standards just those referenced throughout the rest of Div 1 for their use.
In the scope of B36.19 it states that the sizes in B36.10 are also readily available...
Were the measurements in the opening post before or after descaling?
If post descale, the extent of wall thinning needs to be assessed against the design conditions. As already mentioned above, if tmm-FCA < MAWT then you will need to do a fitness for service assessment.
If before descale, the...
Which code and what was the grinding for? Has the vessel been PWHT?
Weld toe grinding? Have a look at 6.2.5.7 in VIII-2. Something similar is in Annex C part C.4 of PD5500. Or was this grinding to blend out an LTA? See MA 32-5 in VIII-1 or 4.14 of VIII-2.
If the location is now above...
Unfortunately not.
What scenario are you trying to design for? You quoted a "low" probability, are you looking at blast over-pressure, earthquake? I seem to recall in pre '07 Div 2 that for linear-elastic analyses there was a k factor applied to the allowable stress and depending on the load...
If this were a repair and you were to follow PCC-2 for insert plates, Article 2.1, it states that where rectangular and square insert plates are used the corners should be rounded to a radius and provides what that radius should be as a function of plate thickness.
A tensile test is for the strength and stiffness of the material, Charpy impact test is a cheap way of measuring/correlating to material toughness.
Which location is this test for, how many samples at this location were tested and what energies were achieved? It's common to have a significant...
Non-Mandatory Appendix A of B16.5 provides the method of how the p-t ratings were determined and includes a design margin on yield and tensile stress.
Agree with the above that flanges are self relieving - as the pressure increases the flanges will eventually part and leak - that's not to say...
Which code has your vessel been designed to and what are the materials of construction?
Why would you want your PTPs to not reflect the heat treatment your vessel has seen? Some codes have means of waiving the requirement for a PTP, i.e. Annex D D.7.2.2 of PD5500, but a project specification...
What's the vessel design code? A new or old vessel? What is the actual zero crossing period, it can vary quite a bit depending on location and over 25 years can change the number of cycles considerably.
You'll need to consider all the acceleration loads on the equipment and consider stress...
Note...
If the equipment was designed to ASME VIII-1 and pre-99a then the allowable stress values in the current version of II-D may not apply (unless you go through API 510 and meet their criteria...). The UTS factor currently is 3.5 but previously was 4 and 5 before that. Depending on your...
In my experience this seldom occurs. I'm not sure about the inner workings of PV Elite so as part of your troubleshooting I'd recommend you investigate what it's doing, but have you read 2.2.2.1(1) in ASME VIII-2 on the specified design pressure and MAWP? There's a similar comment in UG-99...
In one respect the equivalency comment and discrepancy between UG-32(c) and 1-4 is good because it triggers useful discussions between engineers and manufacturers. Conversely, as already stated, although geometrically similar the circumferential stress can be quite different and the discrepancy...
Can't remember the references in BS5500 off the top of me head but in PD5500 it's Section 2.3, Annex K, plus there are also material supplement pages and Enquiry Cases at the back which includes some material allowable stress data.
The UTS factor and occasionally the yield factor is different...
With respect to differences in allowable stresses between the process piping code ASME B31.3 and those populated in ASME II-D (which is primarily intended for use with the B&PV codes) it is due to the factor applied to the ultimate tensile strength.
The allowable stresses in Annex A of ASME...
I have very limited experience in hydrogen service equipment (so take the below as anecdotal) but based on what's been mentioned already it may be worthwhile reading Section 5.1.3.1 of API 571 and API 941.
Also, out of interest, I've also included this video link...
That's quite a few questions that can't fully be answered without knowing more about your particular vessel.
From what information you've supplied and your comments about FEA/stresses you probably need a lot of guidance in that area. From the cursory vessel geometry you've provided (is the...
For Smooth Bar - Equations 3-F.1, 3-F.2 and 3-F.3 can all be combined into one equation. All the equation variables, with the exception of stress amplitude (Sa) and allowable number of design cycles (N), are based on the material and which units you are using. Manually tabulate Sa and...
The S-N curves can be generated from the equations and data included in Annex 3-F of ASME VIII-2. The use of the Smooth Bar or Welded Joint curves will depend on which location and method you are using to do your fatigue assessment.
Lacking any information a conservative and best endeavours approach could be followed, such as:
Select the lowest allowable stress from all carbon steel grades tabulated within the original design code;
Assume minimum NDT and select the appropriate weld quality/strength reduction factors...
