Guided bend test for tube-tubesheet design 1

[Eabrar]

Is there any requirement of tensile test and guided bend test for tube to tubesheet joint according to ASME standards or any other standard. In some of our heat exchanger tesile test and guided bend test is performed.

 

[metengr]

Tube to tubesheet seal welding requires an ASME B&PV Code Section IX qualified welding procedure. Therefore, you would need to qualify the weld procedure using guided bend and tensile testing.

When we have purchased HP feedwater heaters, we had the vendor perform a small mock-up of several tube to tubesheet seal welds using their process. The purpose for this mock-up was to evaluate actual seal weld quality and specifically weld bead size. The reason for this was to make sure that the opening of the tube was not reduced in diameter from the seal weld to prevent Eddy current testing and increased flow velocity thru the tube.

 

[GRoberts]

I believe that the only time tensile and bend tests are not required in ASME IX, is for non-pressure retaining fillet welds. See QW202.2 (c)

 

[deanc]

Take a look at ASME SecVIII Div 1,Appendix A. Review UW-28.

You may not need to qualify the actual joint only the welding procedure and of course the welder.

 

[sayee1]

You need to qualify a procedure which addresses all thge essential variables including the dissimilar thickness. Ideally though this sounds like not the best thing to do, you may need to weld a butt weld between a thicker member(which represents the tubesheet) to a thinner member (which represents the tube). If your tubesheet is not thicker than 8 inches, use a 40 mm plate welded to a plate that could cover you for the tube thickness. Then machine the samples down to thickness of the thinner plate, and carry out tensile and bend tests as per ASME Section IX. As deanc stated, this will qualify the procedure. Ensure all other essential variables of section IX are addresses as well.

Finally, appendix A, section VIII div 1 is a non mandatory appendix, and you may do the destructive tests described (I seem to remember that it is pull out tests that are called for)which actually help one arrive to the values of fr for the actual joint design which I think is used in the design calculations, though I am not sure right now on how/where it was used.

Thanks and regards
Sayee Prasad R
Ph: 0097143968906
Mob: 00971507682668
email: sayee_prasad@yahoo.com
If it moves, train it...if it doesn't move, calibrate it...if it isn't written down, it never happened!

 

[bmoorthy]

Tube to tubesheet joint, whether fillet or groove fillet, needs to be qualified with supporting PQR. Butt joint Procedure Quallification should take care of your groove fillet configuration. If you have only fillet then fillet qualification would do. This is as far as Sec VIII Div 1/Sec IX Mandatory requirement goes.

Further refer to Appendix A. This is in the scope of designers to decide. Here shear load test is called for. Shear load test is not mandatory in all configuration. Shear load test is required under some circumstances. These are listed in Appendix A. Also you may want to refer to UW 28 and UW 12 and UW13.

Some of the Buyer specifications call for this test whether or not Appendix A calls for this test. This approach is over cautious approach. But performing Apeendix A testing does not mean the WPS is supported by the Shear load test. THis shear load test is an additional requirement. Hence supporting Butt joint PQR is a must.

Now comming to your one point question. Bend test, yes this is required as a part of Butt joint PQRT for supporting Groove fillet joints.

Sec VII DIV 2 further elobrates the requirements regarding range of validity of the Pull out test. This can be used as a useful guide.