13.1 For the purposes of determining compliance with the specified limits for requirements of the properties listed in this specification, an observed value or a calculated value shall be rounded as indicated in accordance with the rounding method of Practice E29.

This specification covers wrought niobium and niobium alloy seamless and welded tubes. Material covered by this specification shall be made from ingots that are produced by vacuum or plasma arc melting, vacuum electron-beam melting, or a combination of these three methods. Seamless tubes may be made by any seamless method that will yield a product meeting the requirements of this specification. Welded tubing shall be made from flat-rolled products by an automatic or semiautomatic welding process with no addition of filler metal in the welding operation. The niobium and niobium alloy ingots and billets for conversion to finished products covered by this specification shall conform to the requirements for chemical composition of the following elements: carbon, nitrogen, oxygen, hydrogen, zirconium, tantalum, iron, silicon, tungsten, nickel, molybdenum, hafnium, titanium. When specified, the following elements shall be included in the chemical composition of the specimen: boron, aluminum, beryllium, chromium, and cobalt. The materials supplied under these specifications shall be in the fully annealed condition. Finished niobium and niobium alloy tubes shall be free of injurious internal and external imperfections of a nature that will interfere with the purpose for which it was intended. Hydrostatic and pneumatic tests are optional when the purchaser requires. A hydrostatic test shall be performed on each tube and shall withstand without showing bulges, leaks, or other defects.