Spacer's Dimensions used in a Bolted Joint

Question

Spacer's Dimensions used in a Bolted Joint

struclearner (Structural)

(OP)

1 Sep 24 03:03

How the spacer's dimensions i.e. Outer diameter and thickness (Inner diameter) used in bolted joints, are determined or is there a standard/recommendation for the sizes of the spacers with respect to bolt size.
Any reference to the technical literature/book is highly appreciated.
Thanks & Regards.

LittleInch (Petroleum) · Answer 1 · 2024-09-01 10:32:14

Do you mean like ASME B16.48?

https://www.wermac.org/flanges/dimensions_spades_r...

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

MJCronin (Mechanical) · Answer 2 · 2024-09-01 19:09:52

Why do I get the feeling that he has never heard the word "WASHER" before ?

MJCronin
Sr. Process Engineer

LittleInch (Petroleum) · Answer 3 · 2024-09-02 09:18:22

Well the OP has asked several questions on spacers and rarely or never responded, so I guess we'll never know....

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

struclearner (Structural) · Answer 4 · 2024-09-02 16:57:24

Hello LittleInch,
Thanks for your time for the response. The spacer is a cylindrical part used between bolt head and first member of the joint to increase the length of the bolt, where clamped members are not thick enough for a proper Joint and Bolt stiffness ratio.
The washer is used between Bolt head and spacer upper face.
My original post was to get help regarding the spacer's dimensions with respect to bolt size, that is the spacer inner diameter (clearance hole for the bolt) and the outer diameter of the spacer, these dimensions determine the contact area of the spacer with the member/flange of the joint.

LittleInch (Petroleum) · Answer 5 · 2024-09-02 17:16:49

Well a bit of detail always helps.

Not sure I've ever seen these before and not clear why you would want or need them as your explanation sounds a bit odd to me.

Hence why I doubt these are subject to any code or standard.

Have you considered Bellville washers instead?

Only thing I could find was this https://www.accu.co.uk/cylindrical-spacers/765466-... where it states manufacturing standard - "Not standardised"

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

SWComposites (Aerospace) · Answer 6 · 2024-09-02 18:40:53

What is the application for this joint that needs this spacer?
What do you mean by "proper" bolt to joint stiffness ratio?
From what I have seen this kind of spacer would only be used in very specialized joints where one wants the spacer to crush before the joint fails.

And PLEASE stop making your post text bold; its just annoying.

mfgenggear (Aerospace) · Answer 7 · 2024-09-02 19:02:25

Op
This not a washer, it is used to set a distance between detail parts.
And it depends on the material compressive strength.

SnTMan (Mechanical) · Answer 8 · 2024-09-02 19:25:34

The "spacer" as per mage shown by the OP can be used in bolted joints to increase the bolt length relative to the clamped members. This can reduce bolt relaxation.

See this and this.

I don't know how to design one, but I'd assume you'd want it to be much stiffer than the bolt. And the ID is pretty much known...

Regards,

Mike

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

mfgenggear (Aerospace) · Answer 9 · 2024-09-02 19:38:39

Sn
This appears to be a different application. The part shown by the op
Is much smaller diameter spacer.

SnTMan (Mechanical) · Answer 10 · 2024-09-02 20:38:14

Just went by the text in his second post...

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

dvd (Mechanical) · Answer 11 · 2024-09-03 01:30:26

That spacer looks like a liability. Unless it is DOM tubing and a pretty good analysis conducted, it seems like it could buckle or rupture when used in conjunction with high strength bolts.

MintJulep (Mechanical) · Answer 12 · 2024-09-03 02:23:22

There are good reasons to increase the length of a bolt in some joints.

An alternate way to get many of the same benefits is more smaller diameter bolts in place of few big diameter bolts.

SnTMans's links are a good starting point.

Bickford has some discussion of this. So does VDI 2230: https://www.vdi.de/en/home/vdi-standards/details/v...

mfgenggear (Aerospace) · Answer 13 · 2024-09-03 03:04:07

Yes so it can get corrosion so upon removal it fails. I don't buy it.
In my would shorter is more stiffness, rigidity. To name a few. Longer means it can flex, and can fail. Not convinced.

mfgenggear (Aerospace) · Answer 14 · 2024-09-03 03:07:05

More smaller bolts really depends on the application , like a oil pan, or side cover. Some fixturing not so 1/2-13 please. Or depending on size of flanges or mating parts. And the load it carries.

icebloom (Structural) · Answer 15 · 2024-09-06 08:53:00

Those spacers do look a bit odd. If they are that long you will start putting your bolts into bending.

An authoritative text on all matters bolting including the use of filler plates in different types of connections is Guide to Design Criteria for Bolted and
Riveted Joints by Kulak et al. Can be found quite easily on google, and the research and recommendations summarised in there are the basis of many rules in standards.

mfgenggear (Aerospace) · Answer 16 · 2024-09-06 14:39:20

Yes it's this old mechanics opinion
When bolts are not encapsulated properly
And are designed to have a higher height
Is awkward and cause erratic results when tightening with torque values.
Like them tight on the clamping surface.
Unless there is a unique issue.

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Spacer's Dimensions used in a Bolted Joint