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Welding nuts follow-up

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Title: Welding nuts follow-up

Steve,

Theres one more issue than the heat affecting the material

properties of the nut, and thats cracking the nut.  Materials of

the types used in nuts arent intended to be welded, and are

prone to cracking unless very special procedures are used.

Cracks are like cancer, in that they can grow over time (i.e.,

under cycling), even when they are small From a practical

standpoint, predicting how they will grow can be difficult.  Under

the right conditions, cracks can grow very suddenly, and fracture

a whole part (for example, like a small crack does in ones

windshield).

I too am interested in how you resolve this.  I specify tack

welding of nuts at times, but am judicious on when I allow

this.

      Nick Bassar




From: "S. Gordin" <mailbox(--nospam--at)sgeconsulting.com>

To: <seaint(--nospam--at)seaint.org>

Subject: Re: welding nuts follow-up

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Karen,

In my post, was just relaying the "industry" response to the problem.  =

The manufacturer's position that "it was always done that way, and =

nothing happened" (what else is new). =20

As it is now, it appears that the tack welding of the nuts is not a =

"structural" (load-bearing) connection.  The only intent of that welding =

is to prevent nuts from rotating.  My feeling is that the heat of such =

tack welding should not be able to affect the properties of a relatively =

massive nut. =20

That may change dramatically if the tack welding is incorporated into a, =

say, all-around weld.  In other words, the moment the welding of the nut =

is designed/considered a structural connection, it will immediately =

become unacceptable from both formal and substantial standpoints.

I have some questions about the "industry" response, too.  I am working =

with the manufacturer to resolve the issues, and will report the results =

of my "investigation" as soon as they become available.

Steve Gordin SE

Irvine CA

=20

  ----- Original Message -----=20

  From: Roberts, Karen=20

  To: seaint(--nospam--at)seaint.org=20

  Sent: Monday, June 19, 2006 8:21 AM

  Subject: Re: welding nuts follow-up


  Steve - you lost me when you started talking about A588 steel.  Aren't =

we talking about A563?



  I have heard recommendations by more than one respected member of the =

steel design community that nuts "should not" be welded, but I believe =

the only code compliance issue here is that welding A563 material is not =

prequalified by AWS.  That means that qualification tests (per AWS =

Section 4) must be done with an approved WPS to establish the =

weldability.  There is more involved than just providing a WPS - the =

weld produced with that WPS must be tested. =20



  I have a situation where a welded A563 Grade A nut is being used as a =

structural connection, so the issue for me is much more critical than =

tack welding.



  Karen Roberts, SE

  San Diego, CA







  The real dilemma here is the "weldability" of the ASTM A563 Grade DH3 =

=3D nut. Just a quick look into the ASTM Specification for A588/A =

588M-01 =3D material weldability, the use of a welding procedure =

suitable for the =3D grade of steel and intended service is specified. =

The specification also =3D directs you to ASTM specification A6/A6M =

appendix X3 for the weldability =3D of steel and its references. Like I =

mentioned the other day, the =3D qualifying document here will be a =

welding procedure that covers the =3D base material of the A563 grade =

DH3 nut.=3D20



  As I have more time, I will research more."=3D20



  Steve Gordin SE

  Irvine CA