www.sefindia.org

STRUCTURAL ENGINEERING FORUM OF INDIA [SEFI]

 Forum SubscriptionsSubscriptions DigestDigest Preferences   FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups  RegisterRegister FAQSecurity Tips FAQDonate
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log in to websiteLog in to websiteLog in to websiteLog in to forum 
Warning: Make sure you scan the downloaded attachment with updated antivirus tools  before opening them. They may contain viruses.
Use online scanners
here and here to upload downloaded attachment to check for safety.

Welding of steel

 
This forum is locked: you cannot post, reply to, or edit topics.This topic is locked: you cannot edit posts or make replies.    www.sefindia.org Forum Index -> E-Conference 20th June 2005
View previous topic :: View next topic  
Author Message
acpl_sefi
...
...


Joined: 26 Jan 2003
Posts: 63

PostPosted: Thu Jul 21, 2005 12:04 am    Post subject: Welding of steel Reply with quote

Dear all,

I want to know-- what is the size of weld deposited on a pair of rebars being welded together in relationship to the weld electrode size. COnsequently what should be the length of lap (is there a minimum). Is this a prequalified weld as per AWS or any other standard. If more than one pass is required for welding (say 5mm electrode on a 25 dia bar) what are the precautions to guarantee the strength of the weld (3 passes etc.)

Regards

Vipul Ahuja  


On Sat, 16 Jul 2005 inchak@tatasteel.com wrote :
Quote:
*************************************************
SEFI e-Conference on Steel Reinforcement from June 27 to July 17, 2005
*************************************************
Sponsored by TATA Steel
*************************************************









Thanks for a very topical set of questions.

I proceed to briefly answer each one to the best of my ability.
1) Can normal HYSD bars and TMT bars be welded.
Answer: Welding is permitted and, indeed, carried out. The proposed draft
revision of IS: 1786 (available in the URL:
http://www.bis.org.in/sf/ced/p_7303.pdf) brings more clarity to this
subject. I quote the relevant clause

QUOTE
3.2.2 For welding of cold-worked deformed bars, the recommendations of
IS 9417:1979 shall be followed.
NOTE - Till such time IS 9417 is revised to incorporate the requirements of
Thermo-mechanically treated steel, the recommendations of IS 9417 shall
also apply to
thermo-mechanically treated steel with the provision that the temperature
under clause
10.3.4 of IS 9417:1979 shall not exceed 200 Deg. C for subsequent beads.
UNQUOTE

While this is going to bring complete clarity on this subject, we do not
see the need to maintain an inter pass temperature of 200 Deg. C. TMT is
tempered at a temperature of 550 deg.C or more and is stable with respect
to mechanical properties at least upto that temperature. Rather HYSD bars
(CTD?)attain their strength by cold working and are susceptible to losing
their strength beyond 400 deg.C.

As a result, whatever welding parameter is good for CTD will be good for
TMT as well. An attempt is on to get this suitably incorporated in the
undergoing revision of IS:1786 specification.

2) If welded is permitted, what happens to steel due to heat treatment and
what stress should be considered in design.
Answer:   If welding electrodes of matching strength is used, there is no
loss of strength because of welding.  However, the prevailing provisions of
IS 456 need to be complied with.

QUOTE
26.2.5.2 Strength of welds
The following values may be used where the strength of the weld has been
proved by tests to be at least as great as that of the parent bar.
a) Splices in compassion - For welded splices and mechanical connection,
100 percent of the
design strength of joined bars.
b) Splices in tension 80 percent of the design strength of welded
bars (100 percent if welding is strictly supervised and if at any
cross-section of the
member not more than 20 percent of the tensile reinforcement is welded).
UNQUOTE

3) Some Steel companies claim their bars can be welded, what is their
composition / speciality
Answer: Again one needs to address this question within the boundaries of
IS: 1786. Note 1 of clause 3.2 (page 6, stipulates :

QUOTE
For guaranteed weldability, the percentage of carbon shall be restricted to
0.25 percent, maximum.
UNQUOTE

Further Amendment No. 2 of May 2002 says
QUOTE
Note 1 - For guaranteed weldability, the Carbon Equivalent using the
formula ............ shall be not more than 0.53 percent, when micro
alloys/low alloys are used. When micro alloys are not used, Carbon
Equivalent using the formula ........... shall be not more than 0.42
percent. Reinforcement bars/wires with higher Carbon Equivalent above 0.42
percent should, however be welded with precaution. Use of low hydrogen
basic coated electrodes with matching strength bars/wires are recommended.
UNQUOTE

4) Welding is a common practice in Piles and heavy engineering such as
bridges etc.
Answer: YES. It is also quite safe and extensively used abroad. We should
have no hesitation in adopting this practice wherever it can add value.
Hope you find the responses in order and satisfactory
Thank you once again

Indranil Chakrabarti


********************************DISCLAIMER***********************************
Information contained and transmitted by this e-mail is confidential and
proprietary to Tata Steel Ltd. and is intended for use only by the
addressee. If you are not the intended recipient , you are notified that
any dissemination or copying of this e-mail is strictly prohibited and you
are requested to delete this e-mail immediately and notify the originator.
Tata Steel does not enter into any binding agreement with any party by
e-mail. Any views expressed by an individual do not necessarily reflect the
view of Tata Steel. Tata Steel is not responsible for the consequences of
any actions taken on the basis of information provided. While this e-mail
has been checked for all known viruses the addressee should also scan for
viruses. To know more about Tata Steel please visit www.tatasteel.com
********************************************************************************





The views, opinions, analyses and assessments contained herein do not necessarily reflect the views of SEFI or TATA Steel. Also SEFI and TATA Steel does not guarantee the accuracy of the data included in the proceedings of this e-conference and accepts no responsibility for any consequences of their use.
*******************************************
========powered by Reach1to1 Office Everywhere (http://www.reach1to1.com)======


Posted via Email
Back to top
View user's profile Send private message
Display posts from previous:   
This forum is locked: you cannot post, reply to, or edit topics.This topic is locked: you cannot edit posts or make replies.    www.sefindia.org Forum Index -> E-Conference 20th June 2005 All times are GMT
Page 1 of 1

 

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum


© 2003, 2008 SEFINDIA, Indian Domain Registration
Publishing or acceptance of an advertisement is neither a guarantee nor endorsement of the advertiser's product or service. advertisement policy