8/17/2019 Bottom Nut's Tack Welding on Straigth Anchor Bolt
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Saudi : PEB
GETS-PRD
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Guidelines about Tack Welding of
Bottom Nut to Straight Anchor Bolt
PRD REF : PE-1743-21-00Date : 16 Apr 2013
Introduction:
As specified in “updated ” Standard Specification for
Straight Anchor Bolts, the bottom nut should
be tack
welded to securely lock it with the anchor bolt . On the
case of current stock of Anchor Bolts (which are
not
having tack welding), the required tack welding of the
bottom nut will be implemented.
The said bottom nut should be securely
locked to the anchor bolt due to the risk of becoming
loose or misplaced
as a result of the following;
Movement / vibration during handling / delivery,
Movement / vibration during pouring of concrete,
During tightening of the upper nuts (nuts at the
projected/ top end)
GETS-PRD Saudi found out (based on actual recent testing)
that single Tack Welding under the bottom
nut ofStraight Anchor Bolt is good enough to
securely lock the bottom nut.
Recommended Guidelines about Tack Welding of Bottom Nut to
Straight Anchor Bolt:
With some samples of Straight Anchor Bolts from current
stocks in Buy-out Store, tack welding trials were
conducted at Bay-5 Production line. Below are some of the
relevant points considered during the trial tack
welding of the bottom nut (Refer to Photo 1 on Pages
2).
1. Bottom nut shall be tightened up to
the shank.
2.
Portion to be tack welded should be suitably / properly
cleaned.3. Provide a single tack weld on the
threaded bolt under the bottom nut . Fusion of the tack weld
should be
more on the threaded bolt and very minimal on the bottom nut
(which is quenched / tempered) .
Notes: To ensure quality of tack welding and to ensure that the
anchor bolt’s performance/ properties will
not be affected during the tack welding processes, following
should be considered;
a. It is a must that tack welding be performed only
according to qualified welding procedures by fully
certified welders.
b. Tack welds should be in acceptable/ good quality,
free from pinhole, crater, undercut, crack, lack of
fusion (open seam), etc.
c.
Tack welding should be at the unstressed end of the bolt
under the bottom Nut.
d. Ensure at all times that no welding, arc, or other
potential notch-producing effects occur in the
“stressed portion of the bolt” (or above the bottom nut).
e. Excess heating and/ or longer /
prolonged welding can possibly cause a stress
raiser , notch effect ,
crack starter across the quenched / tempered and highly stressed
nut , hence should be avoided.
4. With the tack welding completed, Zinc Rich Spray
Paint shall be applied on the tack welded area. It is
important that the tack weld and adjacent area must be
thoroughly cleaned prior to application of
the
Zinc Rich spray Paint.
