Nalla

There did not seem to be enough specific information in this post.  Small details make a big difference in TYK Connection qualification using D1.1.   I hope I am interpreting your question correctly.  I think you are implying that your contract does not have a LAST requirement for the Charpys.  I think you are also implying that you need to qualify for round tube and HSS tubing.

I only have the 2006 Code available and the 2010 Code available.  I will use the numbers found in the 2006 Code for my answer.  I also cross checked with the 2010 code which has different paragraph numbers, however the basic details remain the same.

You cannot use JUST use "...6" x Sch XXS x API 5L Grade 50..."  alone, to be qualified for round tubular 6-GR open root qualification.  There must be a 3/16"  thickness difference between the upper tube and the lower tube in the Figure 4.27 coupon assembly, and the minimum wall thickness of the lower tube would be 1/2 inch.  Thus "6" x Sch XXS", with a wall of 0.864 could be used for the upper tube section, a 6" Sch. 120 with a wall of 0.562 would be used for the lower tube section.  As for substituting fabricated plate product for tube, plate products are not made to the same specifications as the tubular sections, so any "mechanical properties" test specimens would not necessarily produce valid results.

When you went to do the Figure 4.29 coupon assembly, you would have to use square or rectangular HSS section with 3/8inch wall thickness.  The Macro-Etch coupons have to be cut transversely through the radius as shown in Figure 4.29, thus you cannot make up your own square tube out of plate.  . 

However, when you do your acute angle coupons for Dihedral angles less than 30 degrees, you would use flat plates.  In this case you are just establishing proof of access and ability to make sound weldments.

No variation from the procedures and details is permitted, IF you are going to claim Qualification in accordance with D 1.1.  In my opinion multiple mock up specimens are required.

Joe Kane