Shane,
please let me add something to the excellent information coming from Jon and Henry.
Doing this just since I have read you have mentioned Euronorm EN 287/288.
There is a lot of "political" uproar with the modification of EN 287 (fusion welding of steel) to "transform" it into a part of the EN ISO 9606 row. Normally EN 287 part 1 (Steel) should have been transformed into EN ISO 9606 part 1, but the standardization committee failed due to caveats. However, the standardization of the other metals and alloys was successful by having now:
EN ISO 9606 - 2 (Aluminum and its alloys)
EN ISO 9606 - 3 (Copper and its alloys)
EN ISO 9606 - 4 (Nickel and its alloys)
EN ISO 9606 - 5 (Titanium and its alloys / Zirconium and its alloys)
For Titanium and its alloys again they have distinguished three different "material groups" for the welding tests according EN ISO 9606 - 5.
They are designated by the letter "W" and as follows differentiated:
W 51 - Pure Titanium
W 52 - Alpha Titanium alloys (e.g. Ti-0,2 Pd; Ti-2,5 Cu; T-5Al-2,5Sn)
W 53 - Alpha Beta Titanium alloys (e.g. Ti-3Al-2,5V; Ti-6Al-4V; Ti-6Al-6V-2Sn)
W 54 - Beta Titanium alloys (e.g. Ti-10V-2Fe-3Al; Ti-13V-11Cr-3Al)
The validity in regard to the material thickness range is as follows:
Test coupon thickness: t <= 3mm --> validity thickness: t <= 2.5 t (mm)
Test coupon thickness: t > 3mm --> validity thickness: t >= 3mm
I have prepared an additional table showing the methods for Titanium welding test results according to EN ISO 9606 - 5, which I would like to attach for your kind information, see the attached pdf.
Hope this helps additionally to what has come from Jon and Henry.
Best regards,
Stephan