If the load is applied in a vertical down orientation and the correct bend radius is in the bent plate, then the load is not carried directly vertical down as it would be if angle had been used. The bend radius in the plate causes the load to be applied to the bend as an offset not true vertical...
Normally there would be no chemical tests applied to Mild Steel. In-house there may be tensile, yield and notch testing done on material from a new or non certified vendor. Usually the plate is purchased from/through a certified distributor or you purchase a mill run order and the steel mill/mfg...
Primarily it's a function of cost, you can patch and band-aid about anything, but there's a point where it's more cost effective to just replace the column.
When you say into, are we talking about physically cutting into the concrete structure or are we talking about attaching a steel ladder manway onto a concrete structure using Hilti installation or expansion anchors?
Where is the question concerning welding - bolting? A structure this size will probably have both welded and bolted joints depending on the design(er).
Take a look at S6 x 12.5, this would be a standard "I" beam, possibly a design firm used this designation vice the standard callout. Same reasoning for the oversize, which should not have much effect on the slip critical joint, though it will be a little sloppy on fit.
Try the web sites for the major mfg's of welding equipment. In the U.S. this would be Lincoln Electric, Miller, etc. Most of them have on line FAQ's and literature available. There is a lot of free literature available from the major mfgs also. Check the internet for Mil specs concerning...
Low hardness in fired tubes is not uncommon, the firing process anneals the tube and if its a welded in application the heat affected zone will be annealed from the welding.
The Nitronic series are stainless steels, the most common we use is Nitronic 50 (UNS S20910) which is Chromium-Nickel-Manganese-Molybdenum alloy. Most steel distrubutors in the U.S. know what it is and it's carried in stock as a Stainless Steel Specialty or Super Alloy. Check with your largest...
Compare the composition against a know metal like ASTM A36, if you have a sample, try filing it with a commom metal file, if it files easy it will machine easy, etc.
Bob,
Using an end mill will help a lot, the edge cuts into the tube wall and helps prevent sliding. The more fool-proof way is to make a "drill guide" and harden it after you have the guide hole, then use an end mill in the drill guide, as even the mill will deflect as it reaches...
