Welding of 8.8 tzn M20x250 Anchor Bolt

By Iqra Date 12-01-2018 12:09

Dear All,

I have a question regarding embedded anchor bolts. As for bridge crane rail installation, we embedded anchor bolts 8.8 tzn (A325, A449) in the concrete, after concrete we found that out of 300 anchor bolts 20 anchor bolts are misaligned up to 33mm. To ensure the alignment of rail we have welded another anchor (of the same material) at the back of with embedded anchor (both sides welded with embedded bolt) for the alignment of rail. As there was no other mean to align the rail.

So I want to know is that allowable to weld 8.8TZN (A325, A449) with the same material?

By Lawrence (*****)

Date 12-01-2018 19:54 Edited 12-01-2018 19:56

HI Iqra

It looks like you already did it.

The alloy rods you described are catagorized as “high strength” and are heat treated. (A325 & A449).

The AISC design guide has prohibitions on both welding and heat bending in excess of 1000F

When heat is reapplied (welding) to a bolt that has been heat treated, it is likely going to result inthe mechanical properties of the bolt being changed in a negative way. When heat is applied in an uncontrolled environment (field welding), it is impossible to predict what effect the application of heat has had on the fastener. Therefore, welding to high strength bolts is not recommended.

Resetting the bolts would have been faster and cheaper then attempting to possibly qualify a procedure to weld the things.... This is likely what should have been done.

That double bevel groove of threaded high strength bolts ON A CRANE ASSEMBLY !

No Principal inspector or engineer is going to consider this an acceptable way to go forward if it includes them sealing the change....

That mess needs to be dismantled and done correctly.

Those terrible welds cannot possibly have a predictable performance on a cyclically loaded crane system.

By Iqra Date 12-02-2018 04:59

Dear Sir,

Thank you for your reply.

Actually, we have 350 + embedded anchors to hold the plate at which the rail has been bolted. Only 20 anchors have deviated and there is no other way to align the rail as Owners do not allow the drilling in the concrete. No welding has been done on those anchors which are holding the rail, but only those anchors have been welded which are used for the positioning of the plate.

Now I am worried about the welded anchors and I am thinking what else can be done to align the anchor and positioning the plate keeping in view that drilling is not allowed in the concrete at any cost. :cry:

Btw really appreciated for your response.

By jwright650 (*****)

Date 12-01-2018 23:47

I agree with Lawrence, welding the high strength bolt is not recommended. I believe you can get a high strength epoxy anchor for future reference.

By 803056

Date 12-03-2018 16:49

It is easier to ask for forgiveness than it is to ask permission......sometimes!

Al