ASME VIII DIV 1 SWING BOLT WITH AN EYE NUT

[mech8790]

Hello everyone,

I would like to cross check with you code compliance of a set of swing bolt and an eye nut. I couldn't find in ASME VIII Div 1 any reference to eye nut (only wing nut is mentioned there) so I believe the code doesn't prohibit it from use. I am not sure if there are any requirements for such nut. Also, the design pressure is very low 1.1 barg.

Cheers!

 

[SnTMan]

Generally speaking, if a thing is not prohibited it is permitted. Since an eyenut does not meet (as far as I know) one of the material specifications recognized under Div 1 its design, fabrication and inspection is on the designer and fabricator.

Regards,

Mike

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

 

[LittleInch]

Can you sketch up what you mean as it isn't clear (to me at least)and one persons eye nut is anothers eye bolt...

a nut is a nut, whether it has a big hole through it or not.

17 psi with a lot of square inches can be a LOT of pounds...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mech8790]

Hi,

Sorry, I forgot to mention the shell size, it is 10'' and I use 4 off swing bolts in the design. I have calculated base on Appendix 2 formulas the force in each swing bolt to be roughly 2 KN. I am only wondering if in this type of design where a swing bolt coming with an eyenut is utilised it will still comply to the code?

Considering any leakage, I have calculated the bolts spacing and compared it with max bolt spacing formula in App.2 for pressure vessels containing lethal medium (the actual medium is not lethal) and the result is a little above (say 5mm) the max spacing calculated by the formula in paragraph 2.5 d) BS max. The sealing is made by use of an O-ring. Is there any formula that maximum bolt spacing can be evaluated for non-lethal medium or only I can do is to stick to the above?

Thanks!

 

[SnTMan]

mech8790, please read Apx 2-6. If not required by the user or agent you need do nothing. At least per 2017 Ed. You should assure yourself the same is true per 2019 Ed.

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

 

[mech8790]

Hi SnTMan,

Thanks for your quick reply. I know this is not a mandatory if not required but I believe it is some sort of an idea how to figure out if a joint is going to be pressure tight, especially when only 4 swing bolts holding the flanges together whereas 10'' flange has got 8 bolt holes. Since an o-ring is used (self-energised gasket) I believe this will provide better sealing than a flat ring gasket with minimum number of bolts.

 

[SnTMan]

mech8790, the issue is not with leak tightness per se, but with deformation of the flange rim between bolt holes. The BSC factor simply provides a multiplier against the flange moments resulting in a thicker flange rim. It is a good practice, but ultimately your choice.

EDIT: It would be more accurate to say "deformation of the flange rim at the bolt holes."

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

 

[mech8790]

SnTMn, I agree with you. Is there any known to you formula to calculate the minimum bolt spacing against leakage? 4 swing bolts compared to 8 bolts of a regular 150# flange is increasing the bolt spacing twice.

 

[LittleInch]

A drawing would really help...

And why you only want 4 bolts instead of 8?

If you're taking this flange off that many times it's going to make a difference I think you need some sort of Quick opening closure

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mech8790]

Hi LittleInch, I am sorry, I can't provide a drawing, but you can imagine a simple vessel with a rolled ring type flange with a blind flange on the top of that. Manual calcualations in accordance with ASME VIII Div 2 show that 4 swing bolts are good enough to carry the pressure load, but I am a little bit worried about the pressure tightness of the joint. The less number of the swing bolts better for the client as we can quickly untide the bolts and replace the material being tested inside for a new one. I believe 150# flange is super tight as we incorporate 8 bolts into design but is the number of bolts the matter here or a gasket used to seal the jont? I was searching through the variaty of the codes but couldn't find any reference to a formula where a maximum bolting spacing can be calculated? Any advice on that?

 

[SnTMan]

mech8790, I doubt such a formula exists with any certainty. A little extra steel, a few extra bolts is cheap insurance. For your class of work bolts need not be added in multiples of 4. You can use 5, 6, 7, whatever. You can apply the BSC while using four bolts. You can do nothing.

On the other hand, once a completely optimized (maximum cheap) design is found to leak in service it generally cannot be saved.

Life is all about choices

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

 

[r6155]

Why not a Standard swing-bolts?
For 10 NPS 3 swing-bolts 5/8”

http://www.nevisenterprise.com

http://www.crallproducts.com

Regards

 

[mech8790]

Hi r6155, I was considering a standard swing bolt DIN 444 with an eye nut DIN582 metric size. Would this be code compliant (ASME VIII DIV 1?

 

[r6155]

@ mech8790
For this low diameter and low pressure I suggest buy a complete closure.

Closures are supplied with a complete documentation package including dimensional drawing, supporting design calculations, material test certificated and, when requested ASME documentation.

Regards