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6. Heat Treatment |
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6.1 Hot finished pipe need not be heat treated. Cold-drawn pipe shall be heat treated after the final cold draw pass at a temperature of 12000 F (650°C) or higher. |
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7. Chemical Requirement |
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7.1 The steel shall conform to the requirements as to chemical composition prescribed in Table 1 |
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8. Heat Analysis |
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8.1 An analysis of each heat of steel shall be made by the steel manufacturer to determine the percentages of the elements specified in section 7. If the secondary melting processes of 4.1 are employed, the heat analysis shall be obtained from one remelted ingot or the product of one remelted ingot of each primary melt. The chemical composition thus determined, or that determined from a product analysis made by the manufacturer, if the latter has not manufactured the steel, shall be reported to the purchaser or his representative, and shall conform to the requirements specified in section 7. |
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9. Product Analysis |
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9.1 At the request of the purchaser, analyses of two pipes from each lot (Note2) of 400 lengths or fraction thereof, of each size up to, but not including, NPS 6, and from each lot of 200 lengths or fraction thereof of each size NPS 6 and over, shall be made by the manufacturer from the finished pipe. The results of these analyses shall be reported to the purchaser or his representative and shall conform to the requirements specified in section 7.
9.2 If the analysis of one of the tests specified in 9.1 does not conform to the requirements specified in section 7 analyses shall be made on additional pipes of double the original number from the same lot, each of which shall conform to requirements specified. |
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Note 2 - A lot shall consist of the number of lengths specified in sections 9 and 15 of the same size and wall thickness from any one heat of steel. |
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10. Tensile Requirements |
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10.1 The material shall conform to the requirements as to tensile properties prescribed in table 2 |
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11. Bending Requirements |
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11.1 For pipe NPS 2 and under a sufficient length of pipe shall stand being bent cold through 900 around a cylindrical mandrel, the diameter of which is 12 times the nominal diameter of the pipe, without developing cracks. When ordered for close coiling (Explanatory note2 ), the pipe shall stand being bent cold through 1800 around a cylindrical mandrel. The diameter of which is eight times the nominal diameter of the pipe, without failure. |
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11.2 For pipe whose diameter equals or exceeds 10 in. (254 mm) a bend test may be conducted instead of the flattening test. The bend test specimens shall be bent at room temperature through 1800 without cracking on the outside of the bent portion. The inside diameter of the bend shall be 1 in. (25.4 mm). substitution of the bend test for the flattening test shall be subject to the approval of the purchaser. |
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11.3 For pipe whose diameter exceeds 25 in. (635 mm) and whose diameter to wall thickness ration is 7.0 or less, the bend test described in 11.2 shall be conducted instead of the flattening test. |
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Note 3 - Diameter to wall thickness ration = specified outside diameter / nominal wall thickness.
Example : For 28 in . diameter 5.000 in. thick pipe the diameter to wall thickness ration = 28/5 = 5.6. |
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