Head Forming Table 1

[loilfan]

Does anyone have a copy of a 2:1 ellipsoidal head forming table that they can upload? I'm referring to a table that tells you what the minimum forming thickness is expected to be based on plate thickness and diameter. I have a table already, but it was an old faxed copy so some of the values are too illegible to read.

 

[mk3223]

Check the link below for the thickness calculation program.

http://www.ksecal.com/ellipsoidal-head-thickness-calculation.php

 

[loilfan]

That appears to be a link to calculating the minimum design thickness per UG-32. Am I not seeing a link to where it calculates the forming thickness by inputting the plate thickness and diameter?

 

[SnTMan]

Found this on Prescor's website. Use at your own risk

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[loilfan]

Thanks SnTMan!

Interesting to see that the values between the two sheets are off by up to 0.030".

 

[Don56]

Call the head manufacturer and ask. It depends on the method of forming, die forming, hot vs. cold, bumped & spun, spun only, material type, size, thickness. Too many variables to say an SE head thins X amount.

 

[loilfan]

Don56, I agree the different forming methods would give different thicknesses. I do not work in the construction of the vessels so I would not have access to the original manufacturer, so the best thing to do would be to collect a number of these tables from various manufacturers and take the most conservative.

 

[FoxRox]

Agree with Don56.

The minimum thickness should come directly from the head manufacturer. If you're not the vessel manufacturer, then simply specify a minimum thickness and let the vessel manufacturer figure out what nominal thickness is needed to stay above the minimum.

I would not recommend using a list of head manufacturers and taking the most conservative. You could come up short if your list is not comprehensive. More likely, you'll come up thicker than you need to, which means extra material and welding cost.

 

[racookpe1978]

You are wondering about an 0.030 difference on one vender's fabrication document?

 

[r6155]

@ loilfan.
This is not a good way to do engineering.

Regards
r6155

 

[loilfan]

Let me better explain my situation.

I am not in the business of constructing vessels. Wasted welding is not my concern since the vessels are already built. I deal with vessels that have seen damage and need to determine the remaining life. Many of the manufacturers who built the vessels have gone out of business.

If we have a vessel with current thickness data (UT) and a tmin, we need to know what the original starting thickness was. Without baseline UT or the forming thickness, we can't determine a long term corrosion rate. I think taking the highest forming thickness would be the conservative approach as it would give the highest corrosion rate.

I also want to use these tables to confirm original design data. I've encountered U-1As with typos before and like to use tables like this as a confirmation that the data is correct.

 

[r6155]

Please, see:

ASME PCC-2 2015 Repair of Pressure Equipment and Piping

API 579-1/ASME FFS-1, June, 2016
Fitness-For-Service

API 510 TENTH EDITION, MAY 2014
Pressure Vessel Inspection Code:
In-service Inspection, Rating, Repair,and Alteration

NB 23 Part 3 NATIONAL BOARD INSPECTION CODE 2015
Repairs and Alterations

Regards
r6155