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ASTM A688-2018 pdf free download

ASTM A688-2018 pdf free download.Standard Speci fication for Seamless and Welded Austenitic Stainless Steel Feedwater Heater Tubes
1. Scope
1.1 This specification covers seamless and welded auste- nitic stainless steel feedwater heater tubes including those bent, if specified, into the form of U-tubes for application in tubular feed- water heaters. 1.2 The tubing sizes covered shall be ⁄ 8 to 1 in. [15.9 to 25.4 mm] inclusive outside diameter, and average or minimum wall thicknesses of 0.028 in. [0.7 mm] and heavier. 1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
6. Materials and Manufacture
6.1 The tube shall be manufactured by either the seamless or welded and cold worked process. 6.2 Seamless Tubing: 6.2.1 Seamless tubing shall be supplied from a cold finish- ing process. Hot finishing as the final sizing process is not allowed. 6.3 Welded Tubing: 6.3.1 The tube shall be made from flat-rolled steel by an automatic welding process with no addition of filler metal. 6.3.2 Subsequent to welding and prior to final heat treatment, the tubes shall be cold worked either in both the weld and base metal, or in the weld metal only. The method of cold work may be specified by the purchaser. When cold drawn, the purchaser may specify the minimum amount of reduction in cross-sectional area or wall thickness, or both. 6.4 Many surface contaminants may have detrimental ef- fects on high temperature properties or corrosion resistance of tubing. Contamination by copper, lead, mercury, zinc, chlorides, or sulfur may be detrimental to stainless steels. The manufacturer shall employ techniques that minimize surface contamination by these elements.
7. Cleaning Before Annealing
7.1 All lubricants of coatings used in the manufacture of straight-length tube or in the bending shall be removed from all surfaces prior to any annealing treatments. U-bends on which a lubricant had been applied to the inside surface during bending shall have the cleanness of their inside surface confirmed by blowing close fitting acetone-soaked felt plugs through 10 % of the tubes of each bend radius. Dry, oil-free, air or inert gas shall be used to blow the plugs through the tubes. If the plugs blown through any tube shows more than a light gray discoloration, all tubes that have had a lubricant applied to the inside surface during bending shall be recleaned. After recleaning 10 % of the tubes of each bend radius whose inside surface had been subjected to bending lubricants shall be retested.
8. Heat Treatment
8.1 All finished straight tubing or straight tubing ready for U- bending shall be furnished in the solution-annealed condi- tion. The annealing procedure, except for N08367, S31254, S32654, N08810, N08811, and N08926, shall consist of heating the material to a minimum temperature of 1900 °F [1040 °C] followed by a rapid cooling to below 700 °F [370 °C]. The cooling rate shall be sufficiently rapid to prevent harmful carbide precipitation as determined in Section 13. 8.2 UNS N08367 shall be solution annealed at 2025 °F [1107 °C] minimum followed by rapid quenching. 8.3 N08926 shall be heat-treated at a minimum temperature of 2010 °F [1100 °C] followed by quenching in water or rapidly cooling by other means. 8.4 S31254, S32654, and N08811 shall be solution annealed at 2100 °F [1150 °C] minimum followed by rapid quenching. 8.5 N08810 shall be heat-treated to a minimum temperature of 2050 °F [1120 °C] minimum followed by rapid quenching. 8.6 If heat treatment of U-bends is specified, it shall satisfy the annealing procedure described above, and shall be done as follows: 8.6.1 The heat treatment shall be applied to the U-bend area plus approximately 6 in. [150 mm] of each leg beyond the tangent point of the U-bend. 8.6.2 If the heat treatment specified in 8.6 is accomplished by resistance-heating methods wherein electrodes are clamped to the tubes, the clamped areas shall be visually examined for arc burns. Burn indications shall be cause for rejection unless they can be removed by local polishing without encroaching upon minimum wall thickness.

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