Here's the results, the recieved e-mail inquirey. They are from a well-known Ti supplier:
I will attempt to answer your questions. However I must stress that we do not produce seamless or welded tubing.The bicycle frame manufacturers use mostly Grade 9 tube. Grade 9 is 3Al-2.5V. They use both seamless and welded tube. Welded tube in general usually has a more uniform wall thickness as it is produced from cold rolled Grade 9 coil. It does have a weld seam. That may or may not be a deterrent to performance. Seamless is cold drawn around a mandrel and may have slight wall variation. Tube specifications have a wall thickness tolerance of +/- 10% regardless of manufacturing method .
I will embed my comments into your e-mail
I WOULD HIGLY RECOMMEND YOU REVIEW AMS 4943 which is for annealed Grade 9, AMS 4944 -cold worked and stress relieved and ASTM B 338 Grade 9 which is for non aero applications as either seamless or welded tube. These 3 material specifications will add credibility to your findings. As an added bit of information AERO tube is usually smaller diameter tube and is for higher pressure hydraulic usage.
1. Ti tubing used for bicycles is NOT Aerospace-Grade, it's Sports-Grade. SEAMLESS TUBE IS ALSO USED FOR AERO APPLICATIONS AND THE DIFFERENCE MAY BE IN THE FINAL PRODUCT TESTING. THERE ARE VARIOUS METHODS OF ANNEALING THIS TUBE THAT WOULD CHANGE THE FINAL PRODUCT TENSILE AND YEILD STRENGTHS. AERO TUBE IS PRODUCED TO AMS SPECIFICATION AS WELL AS POSSIBLE ADDITIONAL REQUIREMENTS FROM THE PURCHASER. NON- AERO TUBE IS USUALLY PRODUCED TO ASTM B 338 SPECIFICATIONS. ASTM has two separate property requirements listed.
2. Ti tubing used in the bicycle industry comes from three sources: U.S. made, China made, Russian made. TRUE, BUT THERE ARE OTHER COUNTRIES THAT MAKE TUBE FOR THIS APPLICATION.
3. U.S. tubing is made on the same machines that make Aerospace-Grade Tubing, but is still considered Sports Grade, regardless. YES AND THE DIFFERENCE IS TESTING CRITERIA NOT MANUFACTURING TECHNIQUE for seamless. WELDED TUBE IS GENERALLY NOT USED FOR AERO APPLICATIONS
4. China Tubing is almost as consistent as U.S. made tubing. Inconsistent means that the tubing's wall thickness is not uniform. NO COMMENT OTHER THAN TO SAY INCONSISTENCIES COULD EXIST IN DIAMETER, OVALITY AND OR CHEMISTRY AND PHYSICAL RESULTS.
5. Russian tubing is very inconsistent and should be avoided. NO EXPERIENCE WITH RUSSIAN PRODUCED TUBE OF ANY GRADE OR ENDUSE.
6. Ti tubes must be properly prepped prior to welding, the edges must be burr-free in order to prevent cracking. VERY TRUE AND TO EXPOUND: EDGE PREP IS IMPORTANT ALONG WITH THE PROPER SHIELDING OF THE WELD AREA WITH AN INERT GAS, SUCH AS ARGON. TITANIUM ALONG WITH OTHER REACTIVE METALS MUST BE WELDED CORRECTLY TO AVOID A CONTAMINATED WELD. ANY TIME THE ATMOSPHERE MIXES WITH ELEVATED TEMPERATURES IN A REACTIVE METAL WELD AREA AND HEAT EFFECTED ZONE THE WELD CAN PICK UP HYDROGEN AND CONTAMINATE THE WELD. PROPER SHIELDING AND SOUND WELD PRACTICES ARE A MUST REGARDLESS OF THE GRADE OF TITANIUM BEING WELDED ALONG WITH THE PROPER WELD WIRE FOR THE GRADE SELECTED.