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Up Topic Welding Industry / Inspection & Qualification / Weld Inspection of A706 Gr 60 rebar to A36 plate for Embed
- - By deckerfaw Date 12-04-2009 15:49 Edited 12-04-2009 15:51
After the visual weld inspection is made per the requirements of D1.4 section 4.4 "Quality of Welds" and the welds appear to be acceptable, an inspector proceeded to follow the the test methods of section 7.6.6 of D1.1 and bent the rebar 30 deg in opposite directions until failure.  The failure occured in the rebar and not in the weld.  I am confused in combining the two inspection of the Codes D1.1 and D1.4.  Further more another field inspection was performed by stricking the rebar with a hammer.  Again the failure was in the rebar and not the weld.  Should the weld be considered acceptable?
Parent - - By waccobird (****) Date 12-04-2009 16:09
deckerfaw
I would be confused too from your question. Was this a stud or Reinforcing Steel
AWS D1.4 is for Reinforcing Steel and AWS D1.1 is for Structural with Clause 7 being for Studs.
I believe your inspector is trying to much here Rebar is not to be confused with Studs two different things, Tell the inspector to tighten up.
Good Luck
Marshall
Parent - - By deckerfaw Date 12-04-2009 17:11
Rebar not studs... So now there is a concern that the fabricated product is defective.  I am trying to formulate a response of why the product as welded is acceptable.
Parent - By swnorris (****) Date 12-04-2009 17:46 Edited 12-04-2009 17:48
deckferaw,

I don't think it's defective.  Welds for rebar should NOT be tested in than manner.  Plus, the scope within Section 7 is for studs, NOT rebar.  Bending of rebars is quite common when used on embedded materials. The location and diameter of the bends during fabrication must conform to the following requirements:  The material should always be bent before welding. The weld should not be closer than 2 bar diameters (2 x db) from the bend.  I thought it was important to illustrate this because if an inspector performs a stud bend test on rebar, odds are that the rebar will fail, and this is why. 
I've also listed the minimum bend radius, which is based on rebar grade and diameter.  Note that ASTM A615 requires a greater bend diameter because the C.E. of A615  is not controlled (typically it's between 0.6 % and 0.7%) whereas the C.E. of A706 is not to exceed 0.55%.     

For ASTM ASTM A706, the minimum bend diameter are as follows:

Bar Dia. (db)     Min. Bend dia. (D)
1/2”                      1 1/2"
5/8”                         2"
3/4”                         3"
7/8”                      3 1/2"
1”                            4"
Parent - - By waccobird (****) Date 12-04-2009 17:58
deckerfaw
do you have an ASTM Standards book It gives bend test procedure to test bending properties in A706/A 706M clause 9
Maybe you got something else because A706 is developed for welding applications.
The other thing you might think about is the heat input of the weld causes brittleness in the Heat affected Zone thus fracturing out of the weld.
Good Luck
Marshall
Parent - By deckerfaw Date 12-04-2009 21:07
I had checked the MTR against bill of material and the material is stated as A706  bars came pre bent with a 4" hook, it was then welded to the A36 plate.  Min preheat for a #8 A706 is 50deg F which was met.  The issue is in the HAZ where the #8 rebar wants to fracture when struck.  Pre heating can definintly help with some of the issues.  Me I think it's just a poor design.  Welded studs could have been asked to substitute, or possibly an A36 round bar welded then the #8 bar lap welded to the A36...  The weld itself is good, it's how welding changes the make up of the #8 Rebar.  I have just been looking for suggestions.
Parent - By Duke (***) Date 12-05-2009 01:52
I think your inspector might be wrong on this one... unless your iron was a shot-on DBA, in which case I would treat it as a stud under D1.1. 
A bent bar with the tail flare bevel welded to structural steel, visual inspection only.  Unless there was something in the Plans or Specs.  Was this preproduction testing?
Parent - By Duke (***) Date 12-05-2009 18:15 Edited 12-05-2009 18:17
I took a couple of days off once, (a long long time ago)  studs were getting shot thru deck in the field, and the inspector they sent out to replace me did that, bending till failure, on pre production testing in the field, he confused 7.6 with 7.7, when I came back, the welders told me the replacement almost went in the hole. Oh, and he was bending SMAW welds studs, too.
95% of inspectors are godlike in intelligence, but every once in a while.... 
- - By malCWI (*) Date 02-14-2010 19:41
I too believe the inspector made a mistake and the contractor now has to pay for his mistake. It has been awhile since the last time I've inspected re-bar but I think it just gets a visual. The acceptance criteria is stated in AWS D1.4 have your inspector get a copy or better yet you see if you can get one then instruct the inspector as to what you have found.
Parent - - By 803056 (*****) Date 02-15-2010 04:23
You are not dealing with an inspector, you are dealing with a whack job claiming to be an inspector.

Get a copy of D1.4 to find out what the inspection requirements are. VT is all that is required unless the contract specifies additional NDT.

The bend test, i.e., 30 degrees in one direction is for the qualification of welders when fillet welds only are specified. It is not a requirement for production welds.

As for the mistake, bill the inspection agency for the repair work. They made the mistake of sending the inspector-wanna-be to the site.

Al
Parent - By CWI555 (*****) Date 02-15-2010 11:18
I am smelling back charges...
Up Topic Welding Industry / Inspection & Qualification / Weld Inspection of A706 Gr 60 rebar to A36 plate for Embed

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