Return to index: [Subject] [Thread] [Date] [Author]

Re: Rolled Threads

[Subject Prev][Subject Next][Thread Prev][Thread Next]
ANSI B 18.2.1-1991(R1992)/ASTM B 18.2.1-1996:

"2.4 Body Diameter

"The body diameter minimum/maximum limits of each of the eight products
included in this Standard [Square Bolts, Hex Bolts, Heavy Hex Bolts, Hex Cap
Screws, Heavy Hex Screws, Askew Head Bolts, Square Lag Screws, Hex Lag
Screws] are defined in each of the respective applicable tables.  *Unless
otherwise specified by the purchaser, the body style supplied shall be
full-size body.*" [Emphasis Added]

Note (7) to tables:

"(7)  Reduced Diameter Body.  Bolts may be obtained in reduced diameter body
style.  These shall have a body diameter of not less than the minimum pitch
diameter of the thread and not exceeding the minimum body diameter, E, min.,
shown in Table ... ."


A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Christopher Wright wrote:

Before commenting, I may have sounded a little hard on you--I didn't mean
that. After all, we old farts have to stick together. I meant to point
out that it's never a good idea to argue over standards until you know
the standard. It's an especially bad idea to assume your contractor was
fully informed on engineering issues. He may have been, but you won't
know that until you've read pertinent parts of the standards. I can't
tell you how many times I've had to field and correct comments and
objections from people who simply parroted (albeit in good faith) what
they'd been told without checking basic facts.

>that is not an option since the agency that checks
> California public schools has ruled that rolled threads are not acceptable
I find this very odd on the face of it. Rolled threads have been in
common engineering use for at least 30 years in everything from nuke
plants to aircraft. The metallurgy and thread form provide superior
fatigue resistance. I'll defer to your judgement, but if it were my job
I'd do some digging and I'd start by going to someone in the agency who
knows the background of the requirement.

>It seems that the use of rolled threads would cause several problems if the
>bolts were used to transfer shear forces in steel connections.  The smaller
>shank would result in a reduction in the shear capadity of the bolt.
All I can tell you is that A-307 requires that Grade A and B bolts meet
ANSI B18.2. ANSI B18.2 shows that the shank dimension is not smaller that
the major thread diameter and therefore _must_ be larger than the minor
diameter or the diameter corresponding to the stress area. The dimensions
are specified by ANSI B18.2 irrespective of production method. If the
bolt doesn't meet the standard, it's ca-ca-doody-poo-poo (as we say in
the ME biz) and to be rejected.

>I did visit the engineering library at UC Berkeley, and they did not have a
>copy of ANSI B1.1 or B18.2 and I could not find the necessary information
>in other references
I know they've got it because I just finished checking their web page. If
you want to buy it the cost is $71, so you save $70, right there. No
doubt they have a copy of ASTM A-307, too.  If you don't want to buy it
the thread profile information and bolt standard information is in
Machinery's Handbook. Border's has that, so you can go in and copy it if
you like. It's a fabulous reference--you might want to buy it.

>But if that level of perfection is required I would
>suggest that not one structural engineer in a thousand currently fulfills
>this ideal
If I thought this were true, I'd be alternately laughing and
crying--laughing when I thought that I know more than 99.9% of my peers
or crying when I thought that 99.9% of my peers are so ignorant of basic
information needed to practice.

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at:
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*   Questions to seaint-ad(--nospam--at) Remember, any email you
*   send to the list is public domain and may be re-posted
*   without your permission. Make sure you visit our web
*   site at:
******* ****** ****** ****** ******* ****** ****** ********