DIN 28007 - Tolerances for columns - Part 1 Question

[ThijsM]

Hello all,

The columns and vessel in our Ethanol distillation plant have been designed according to a German standard called DIN 28007. Unfortunately, there is no EN or NEN standard that is equivalent to this standard. At least, not to my knowledge, and these are the standards that my company is willing to buy.
The reason for looking for this standard is because I need to know the tolerances of the vessels, drums and columns we have. Most items are designed for low pressure (-1/+0.5 barg or -1/+5 barg), and I am looking for the rupture or burst pressures.
The engineering company has provided drawings stating that the drums and columns are designed according to DIN 28007-1, which I can not see/find at the moment. Contacting this company did not results in any answer so far.

Can somebody provide me with the tolerances mentioned in this standard?

Thank you

 

[racookpe1978]

You are perhaps confusing "the regulation" with "the actual design" of these pressure vessels.
Yes, they should be built to a standard, and the supplier has told you what that standard is. HE is the one who MUST "design" each vessel to meet (or better yet) exceed that standard by a factor reasonable for your client's lifecycle and potential future changes.

The supplier MUST provide you with HIS calculation sheets for each vessel. Service conditions (pressure, temperature, loads, ratios, corrosion margins, thinning margins due to forming, etc. Those spreadsheets (calculation pages when we did thm manually) will give yo the thicknesses THEY HAVE PICKED. Yes, there will be absolute bare minimums, and yes, you can back calculate those minimums using the code. But that won't tell you hat they actually chose and what alloy they chose.

 

[ThijsM]

Hello Racookpe,

Thank you for your reply.
We need this figure for the consequence analysis and the HAZOP that we do, we need to know the pressure at which the vessels, columns and heat exchangers will burst. This is according to these standards, and therefore I would like to have this figure. We have now assumed a value of 2,5 times the design pressure, but I would like to have confirmation whether this is correct or not.

Greetings,

Thijs

 

[racookpe1978]

Your assumptions is absolutely invalid.

Now, go back to the design documents from your supplier, and look up the actual calculation table of wall thicknesses for each pressure vessel.

 

[XL83NL]

Hi Thijs, based on your username I assume your Dutch just as I am.

DIN 28007 only specifies geometrical tolerances. For example, how much a vessel, when it has a tangent-tangent line of 6000 mm., may deviate from that dimension.

Assuming this vessel is used within the EU (Netherlands?), I assume it's outside the scope of the PED due to the design pressure of 0.5 bar(g) (the vacuum condition does not 'put' the vessel into the PED, PED only looks at gage pressure above 0). You therefore need to contact the MFR, as racookpe mentioned, and ask them for the design code of the vessel, if this is not provided on the drawing. Since this outside PED, and hence often designated SEP, the MFR may very well have not used any design code and just considered this vessel from a structural point of view, and used DIN 28007 for tolerancing his dimensions. Therefore this may give confusion as to the applied design code (for which I guess, as mentioned, no design code has been used at all).

If you need to know the burst pressure, you're on the wrong path, as racookpe mentioned (unless youre doing something exotic in lab experiments of which we have no idea - but I assume you dont based on your OP (original post)). You need to determine the MAWP (Maximum Allowable Working Pressure), using an accepted design like EN 13445 or ASME VIII Div 1. Then you need to contact a NoBo that you want to rerate this vessel; if you do want this, it wall fall under the PED, which may require NoBo intervention.

Knowing the MAWP gives you an idea to which maximum level you can use the vessel. The only reason I can think of for which you want to know the burst pressure is that certain companies use this figure for determining SIL classifications. However, data for bursting pressures of vessels is normally never calculated. The MAWP is quite often not calculated, which is below bursting pressure. I doubt if design codes provide methods for calculating bursting pressures - the only way I can think of now is using FEA.
But it's the other way around usually, the design pressure of the system (thus vessel) is used for the HAZOP. Design pressure and MAWP are often set to be equal to each other, for the ease of engineering.

PS: NEN ISO 13920 is an equivalent for DIN 28007.

Hope this helps.