×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Welding vs Bolting on existing structure during Upgrade

Welding vs Bolting on existing structure during Upgrade

Welding vs Bolting on existing structure during Upgrade

(OP)
I would like to seek opinion of the forum members on
welded vs bolted structural steel connections on existing steel structures.

The questions which come to the mind are:-

1)Whether it is good practice to weld on to a hot dip galvanised existing steel structure,considering that during hot dip galvanisation,changes to microstructure of steel
penetrates well below the surface.

2)Which is easier and takes lesser time, drilling bolt holes on a existing steel structure or welding ?


3)Pipes spools with wall thickness upto 75mm are routinely
  welded on site, why then are we reluctant to weld    
  structural steel sections on site ?

Rgds

RE: Welding vs Bolting on existing structure during Upgrade

1.  It seems to me that welding should be done before galvanizing wherein possible.

2.  Welding generally would take less time, assuming a nominal thickness of steel plates to drill through and the number of holes to drill.

3.  In general, it is widely acknowledged that field welding isn't something that should be attempted without necessary precautions to prepare the field area to a level of that with the shop.  Preheat is important as is the skills of the welder.  Most shop welders weld day in and day out.  Mosts field welders weld on an infrequent basis.  Add to this the lack of inspection that may be required for special welds and bad practice along with fatigue related problems and you've got potential problems.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

RE: Welding vs Bolting on existing structure during Upgrade

Galvanized steel can be successfully welded, however it is very "unpleasant" to do so. The (molten) zinc coating tends to "pop" and "spit" during the process. Most welders don't like to do this.

I have to respectfully disagree with Qshake on the limited usefulness of field welding. In certain applications, such as splicing very long (driven) steel H-pile, field welding is the norm. This is performed with the (partially driven) H-pile in place; field conditions can be "atrocious". However, when a skilled welder performs the work, there are rarely any problems.

www.SlideRuleEra.net

RE: Welding vs Bolting on existing structure during Upgrade

As a GC who has done a significant amount of steel seismic retrofit work I always ask the Engineer to consider bolted connections in lieu of welded if the existing steel is galvanized.  It takes a considerable amount of time to properly prep the joint for a weld if it has been galvanized and it never really gets clean.  It is faster to drill and bolt than it is to properly prep galvanized steel for a weld.

Another aspect to consider is the QC.  It is much easier (in my opinion) and economical to perform QC on bolted connections.  Once everyone is on board with the ro-caps, skidmore tension proofing, torque, and "turn-of-the-nut" the process can move along quite nicely.  It is also easier to get craft workers who can bolt than it is to get someone who can properly weld galvanized steel.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources