ASTM B891/B891M-19 covers seamless and welded titanium and titanium alloy tubing on which the external or internal surface, or both, has been modified by a cold forming process to produce an integral enhanced surface for improved heat transfer.
ASTM B891/B891M-19,Standard Specification for Seamless and Welded Titanium and Titanium Alloy Condenser and Heat Exchanger Tubes with Enhanced Surface for Improved Heat Transfer.The size of this file is 3.08M.
Tubing purchased to this specification will typically be inserted through close-fitting holes in tubesheets, baffles, or support plates spaced along the tube length such as defined in the Tubular Exchanger Manufacturer’s Association (TEMA) Standard.2 The tube ends will also be expanded, and may then be welded. Tube may also be bent to form U-tubes or be coiled or otherwise formed, although tight radii may require unenhanced length for the bends.
The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the order. Combining values from the two systems may result in non-conformance. Within the text, the SI units are shown in brackets. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order.
4. Ordering Information
4.1 Purchase orders for tubes described in this specification should include the following to describe the tubes adequately.
4.1.1 ASTM Specification B891 designation and year of ISsue.
4.1.2 ASTM Specification B338 grade number.
4.1.3 If either welded or seamless is required for base tub.
4. 1.4 Quantity (number of pieces )and the total tube length to be suppled under the purchase order.
4.1.5 Base tube dimensions: diameter, wall thickness (average or minimum wall thickness must be specified), tube length(s)
4.1.6 Enhancement: configuration of finned surfaces (fins per unit length, fin height, wall thickness under fin, etc -refer to Fig. 1)， configuration of ribbed surfaces (pitch, height. thickness of rib- refer to Fig. 2). length of plain ends, location and length of lands(refer to Figs. 3 and 4)
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