【国外标准】 Standard Specification for Niobium and Niobium Alloy Seamless and Welded Tubes

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.AbstractThis 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.1.1 This specification covers wrought niobium and niobium alloy seamless and welded tubes as follows:1.1.1 R04200-Type 1—Reactor grade unalloyed niobium,1.1.2 R04210-Type 2—Commercial grade unalloyed niobium,1.1.3 R04251-Type 3—Reactor grade niobium alloy containing 1 % zirconium, and1.1.4 R04261-Type 4—Commercial grade niobium alloy containing 1 % zirconium.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.3 The following precautionary caveat pertains only to the test methods portion of this specification. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.