ASTM B428-93 pdf free.Standard Test Method for Angle of Twist in Rectangular and Square Copper and Copper Alloy Tube.
1.1 This test method establishes the requirements for thedetermination of the angle of twist in rectangular and squarecopper and copper alloy tube.
1.2 This standard does not purport to address all of thesafety concerns，if any,associated with its use. It is theresponsibility of the user of this standard to establish appropriate safety and health practices and determine the applica-bility of regulatory limitations prior to use.
2.1 The rectangular or square copper alloy tube covered bythis test method may be used in applications in which controlof twist is important to proper fit in final assembly and tominimize rework to bring the tube into compliance. It isrecognized that the amount of twist, in degrees, per incrementof length can change as a result of the weight of the productand its length during measurement.
2.2 This test method provides a procedure for measuring thetwist in square and rectangular copper and copper alloy tubesas a measure of the deviation from straightness.
2.3 This test method allows the purchaser and supplier ormanufacturer to inspect square and rectangular copper andcopper alloy tube with a standard technique that providesacceptable twist in delivered tubes.
3.1 Horizontal Reference Plane (see Fig. 1 and Fig. 2) ofsufficient length to support the tube specimen and a clampingdevice to hold one end of the specimen against the referenceplane.
3.2 Transparent Plastic Protractor Segment engraved withangle lines as shown in Fig.3.
4.1 Place the tube specimen lengthwise on the reference plane. Whenever the specimen has noticeable edgewise curvature, place the specimen so that a side having convex curvature is in contact with the reference plane. Further placement requirements are as follows:
4.1.1 For rectangular tube, place a major outer dimension side (width side) against the reference plane, as shown in Fig.1.
4.2 For square tube, having curvature along all edges, place the specimen so that the side with the least convex curvature is against the reference plane.
4.3 Position the protractor segment flush against the freenend of the specimen, as shown in Fig. 2, and measure the total angle of twist by reading the degrees for that angle line which most nearly coincide with the lower outside edge of the tube end. In making this reading， keep the lower edge of the protractor segment in contact with the reference plane or hold it parallel to this plane by use of the parallel face blocks.
4.4 The angle of twist per unit length is the total angle of twist for the specimen divided by its length and shall be calculated according to the units specified in the material
5.1 This test method is unffected by edgewise curvature of the specimen, and the precision for measurement of total angle of twist is 0.5°.
5.2 This test method has no bias because the values of twist are a direct measurement based on the accuracy of the protractor and the observation of the operator.ASTM B428 pdf download.