Please help to verify weldment size 1

[LSUUR]

Hi all

I am working in pressure vessel fabrication company.
Recently I got comments from our customer but I could not answer from my collegue and calculation company.

I'd like to explain briefly.
It is related to pressure vessel(horizontal type) internal weld(tubesheet to shell).
Tube sheet is non-pressure part and is for fixing filter element.
Tubesheet have some accessary(filter element support plate)
Tubesheet is welded to vessel inside with 4mm fillet weld leg.

Question is 4mm fillet weld can bear filter element weight(approx.250kg, 1M long)/its support(approx.280kg, 1M long).

Could you help me how to calculate or advice?

I have attached file for understanding

 

[goutam_freelance]

It seems your fillet weld will be subject to bending, and shear loads.

You need to estimate the loads correctly and then refer to 'Shigley-Mechanical Engineering Design' Chapter 9 where calculation methods for welds with bending, tensile and shear loads are given.

Best of luck !

 

[HTURKAK]

Dear LSUUR ;

Pls correct me if i misunderstood the problem:

-The tube sheet 40 mm thk is a solid circular plate, does not experience internal fluid pressure, ( or subject to similar internal pressure from both sides ) and wt 250 kg,
- The filter element weight(approx.250kg ) and its supports (280 kg ) 1M apart from tube sheet,

- The fillet weldment 4 mm is continuous ,in circular form with dia .1000 mm,

In this case we can assume that the tube sheet is rigid enough and will transfer the developing bending and shear ( total wt ) to the fillet weldment 4 mm thk.

- Bending moment calculation = with units kg, cm ..

M = ( 250+280 )* 104 + 250 * 2= 55620 kg- cm

This moment will be resisted by circular weldment and one can calculate the horizontal shear with circular section flexural bending stress formula

fh = 1.273 M/ D**2 = 1.273* 55620 /( 100*100 ) = 7.08 kg/ cm and for 4 mm thk, 7.08/0.4= 18 kg/ cm2

The horizontal shear stress will be max . at top and bottom .


Total vertical shear = 250+280 + 250 = 780 kg.

Max shear stress vmax= 2V/ A= 780*2 /( pi*100*0.4)=6.2 kg/ cm2

If we consider a clock with top 12 a clock, bottom 6a clock,

The horizontal shear stress due to bending will be max. at 12 and 6 a clock, and the value is 18 kg/ cm2 and zero at 3 and 9 a clock

The vertical shear stress due to weight of set up will be max. at 3 and 9 a clock, with the value 6.2 kg/ cm2 and zero at 12 and 6 a clock

If you want to find intermediate values for different angles , use bending ( My/I) and shear formula (VQ/It ) and combine with directional combination.

 

[Strook]

LSUUR,

Some side notes, it's concerning to hear that you've arrived at a 40mm tubesheet which isn't pressurised and attached to the shell with a single 4mm fillet weld. It's likely that the tubesheet and its attachment to the shell should be designed to pressure equipment codes such as ASME.

 

[dik]

He could multiply it by 2.2 and do the design in pounds...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[drawoh]

dik

That's fine. Pounds are a unit of force. Pounds per square centimetre are a unit of pressure, although I make a point of staring blankly and stupidly at people who say "centimetres" to me.

--
JHG

 

[dik]

I comfortably work in both, but am a bit of a dinosaur... in Imperial things are immediately obvious, with metric, I still have to give it a thought... not automatic.


forgot to add... that' why I added the happy face...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[HTURKAK]

The OP provided the weights in KG . KG is common weight unit and not only the mass. It could be better to use the notation Kgf ( kilogram force ) One kgf is equivalent to 9.81 N.

 

[drawoh]

HTURKAK,

No, it is not. Kilograms measure mass. When you start doing dynamic analysis, you have to figure out where to insert the gravitational constant in your equations. If you are not clear about weight and mass, you will get it wrong.

--
JHG

 

[dik]

kg, although technically mass is occasionally used as a force... just like lbf and lbm... are sometimes used.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Strook]

Drawoh,

Kg.f is widely accepted and no different to using lb.f.

Leave the imperialist mindset at the login portal and youll do well in this community.

 

[dik]

Do you want to get into 'slugs'?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik