Bolted flat end / openings according to AS1210

[hartsa]

Hi all,

I am trying to figure out thickness of bolted flat end according to Australian AS1210.

You can see the plate and openings attached.

I calculated the minimum thickness with equation 3.15.3(2) in AS1210 and got the result of t=26.93mm. Next I calculated required increased thickness with rules in clause 3.18.9.4 (b) and got the increased thickness of t=38.1mm.

Now, did I understood correctly the rules in clause 3.18.9.4 (b)? it says "... by doubling quantity under the square root sign." That's how I got the t=38.1mm. I multiplied the value under the square root by 2.

Next I realized that the reinforcement rules apply if I have only one opening. Then I tried to apply rules in clause 3.18.12.1 and 3.18.12.2, but it seems like they are guiding me back to clause 3.18.9.

How this should be done?

I know that I didn't gave any specifications for material, temperature or pressure because I just want to know that have I calculated correctly so far (I know for a fact that minimum thickness t=26.93 is correct) and how these multiple openings should be treated?

Thanks for in advance!

Hartsa

 

[doct9960]

Hartsa,

I am not familiar with AS 1210, but it seems the rules for flat heads in AS 1210 are similar to the rules in ASME VIII-1 (UG-34 & UG-39). The AS 1210 rule of "doubling quantity under the square root sign" is similar to UG-39(d)(2).

If I were to apply the rules of ASME to your case, I would multiply 1.406 to 38.1 mm. Getting a required thickness of 53.6 mm

I got the factor h = 1.406 from the formula in UG-39(e)(2):
h = sqrt(0.5/e)

e = [(p - d_ave/p)]_smallest

where:
e = smallest ligament efficiency of adjacent opening pairs in the head
p = center-to-center spacing of two adjacent openings
d_ave = average diameter of the same two adjacent openings

See if AS 1210 mentions a factor similar to ASME's "h". If not, then the AS 1210 rule of "doubling quantity under the square root sign" is most probably for a single opening. You will need to calculate reinforcement for multiple openings the normal AS 1210 way.

 

[gr2vessels]

hartsa,
The good news is you just made it for Clause 3.18.12.3 by 2 mm or so. Then apply 3.18.9.4(b) and calculate the available reinforcement from actual thickness minus 26.93 mm. Then use 3.18.12.2 (which requires 50% of the reo to be the in the ligament between two holes) and check with 3.18.19.4 (b), for the final selected thickness complying with 3.18.12.2. I would rather use, however the latest ASME VIII PV Elite or similar, the AS 1210 '97 edition is today really obsolete....You'll save money and fabrication also...
Cheers,
gr2vessels

 

[hartsa]

Thanks for replies.

doct9960,

It seems like that AS1210 doesn't have similar factor h as in ASME. But did you ment that unpierced thickness (26,93mm) should be multiplied with factor h?

gr2vessels,

I didn't quite understood your advice. Can you be more specific, so that rookie like me could understand

For comparison,

In EN 13445-3 (European standard for unfired pressure vessels) it goes like this.

first you have to calculate factor Y2 from equation,

Y2 = (j / (j - d))^0.5 where,

j = the distance between the centres of the openings
d = average diameter of openings

and then we can calculate minimum thickness for this pair of openings from equation,

e = Y2 x e0 where,

e0 = minimum thickness for unpierced flat end.

Looks like the rules in ASME and I think that rules in EN13445-3 are based on ASME.

 

[gr2vessels]

Sorry hartsa, I was under the impression that you were interested in how to figure out the thickness of bolted flat end according to Australian AS1210.
My reply is quoting the relevant clauses from AS 1210, to guide you in calculating the bolted flat end with multiple openings. I did not intended to make any analogy with other international pressure vessel codes and I didn't intend to supply the calculations in the post. I believe that is more beneficial to you, if you follow closely the quoted clauses and calculate yourself the required thickness.
cheers,
gr2vessels

 

[hartsa]

gr2vessels,

Your absolutely right, I am trying to calculate thickness of bolted flat end according to AS1210. But there are some sentences in the code that I cannot understand.

For example, in 3.18.12.2 "at least equal to 50 percent of the total required for these two openings". What is total required reinforcement for two openings?

And in 3.18.12.1 "combined reinforcement that has a strength equal to the combined strength of the reinforcement that would be required for the separate openings."

I don't understand how this works. I understood that I can use equation 3.15.3(2) to determine the minimum thickness for unpierced end and then use clause 3.18.9.4(b) to determine increased thickness for flat end that has single opening?

But how can I use those rules in clauses 3.18.12 mentioned above? I cannot fit those sentences to a form of equation.

I didn't ment that you should write these equations for me, but I would appreciate if you could explain them a little more detailed to me. I mean like, what to do and when and so on...

Thanks

 

[Juko]

Hi Hartsa, i see now several threads where you need help, info and a supply of bolts.

Try us at Hydrobolt Ltd in the UK as we are a manufacturer and supplier of bolts.



Cheers

Ian 0044 1902 878082

Hydrobolt Ltd

http://www.hydrobolt.co.uk