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A tank that needs hot tapping at multiple elevations has liquid level that results in hoop stress of 15,000 psi. The material is known toughness, but I'm still leery of welding on the shell with that high hoop stress. API 653 states that materials of unknown toughness shall limit hoop stress...

Great tip JStephen. I see the max allowable compressive stress for longitudinal loads only, is 1.8X10^6t/R, and for longitudinal an circumferential compression stress, it's 10^6t/R. Still curious where the large 10^6 coefficient is derived from? Thanks again!

I'm trying to better understand the equations in E.6.2.2.3. Can someone help me understand what's in the coefficient 10^6 of the allowable stress equation 10^6*t/D? I think it must be some derivation possibly including 1.33FY/(12D/t) (1.33 for ASD times yield stress, all divided by D/t)...

That seems plausible- maybe a constructability issue. With the stiffener inside, they were able to run equipment in the gap between tanks...?

API 650 12th Ed, 9.2.2.3- For materials to be used at design metal temps less than 10*C, the qualification of the procedure for vertical shell welds shall include impact testing. Hope this helps-

For guidance, check API 650 12th Ed, Section 5.1.3. For group I, II, and III (A283 is Group I), manual welds greater than 6 mm shall be multipass, and semi-automatic welds greater than 10 mm shall be multipass. So you need to consider if you are welding using manual process such as SMAW? OR...

IFR- can you suggest a reference for hand calculating the stress on the roof due to the pointload?

I see... the thickness limits, indicated as a supplementary variable in Table 255 reference 403.6. The supplementary variable come into play when impact testing is required. Otherwise the qualified ranges are taken from Tables 451. Thank you for your help.

Thanks for getting back to me. Where does it specify that 403.6 is relative to impact testing? I'm sure it's right there, I just can't see it. I do require impact testing. Is section 403 related to impact testing? Because I have impact testing, does the combination of 403.2, and 403.6 mean...

I'm confused by the ASME IX, 403.2, "the max thickness qualified is the thickness of the coupon", and 403.6, "the minimum base metal is T/2 when T<1/4".. Compare that to the table 451.2, where a coupon over 3/8 is qualified for thickness range from 3/16 - 2T. I want to develop a WPS that...

I will appreciate receiving experienced perspective with tanks resting on sand (inside the ringwall), vs resting on concrete. Have you seen many tanks that rest on concrete (inside the ringwall)? Are you aware of any benefits of using one, or the other? Sand may help with drainage. Sloped...

DISCUS?

It's possible with the acceptance of the owner according to the conditions of 12.3.2. Hydrogen test is a common substitute if water is an issue.

Weld neck is a tricky weld to make in the field, and requires x-ray. I would gouge the damaged flange off, and replace with RFSO. Is there concern with heat affected zone HAZ? Remove 1/2" past weld from the neck- there will likely still be plenty of projection. Does the job- economical-

Anyone have a chart that suggests column seal material by application? I have a Naptha storage tank with internal floating roof. I'm looking for guidance in replacing the column seal material. I had a recommendation to use teflon, but I think teflon is too stiff. I appreciate if anyone is...

I'm having a difficult time understanding the distinction between ring wall overturning moment (Mrw) and slab overturning moment (Ms). Mrw is less, and defined as the portion off the total moment that acts at the base of the shell perimeter, Ms is defined as the total overturning moment acting...

I'm using an 1/8 inch EPDM gasket for liquid service (4' head for- a tank launder). It's economical to provide the large gasket in sections that require dove-tailed joints. I'm faced with the option to simply rely on compression of the joint for sealant, of we could go the extra step and glue...

The required bearing area for the foundation could possibly be governed by the seismic case. In other words, the seismic overturning moment imparts a force to the sub grade that has to be taken into account. Regarding code- I believe ACI 318 will be your guide. I'm not familiar with any...

Thanks for the comments. Would control joints be a worth while recommendation? Or, just an unnecessary cost?

Actually, what I'm questioning is- if 1/2 inch fillet is enough for the flg-neck weld of the FCO, why isn't it enough for the same weld of the manway? Additionally, based on the point you raised regarding weld distortion, I'm curious, does anyone actually sell FCO that isn't machined? And...