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17. Nipples |
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17.1 Nipples shall be cut from pipe of the same dimensions and quality described in this specification. | |
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18. Permissible Variations in Weight and Dimensions |
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18.1 Weight - The weight of any length of pipe shall not vary more than 10 % over and 3.5 % under that specified. Unless otherwise agreed upon between the manufacturer and the purchaser, pipe in NPS 4 and smaller may be weighed in convenient lots; pipe larger than NPS 4 shall be weighed separately. |
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18.2 Diameter - variations in outside diameter shall not exceed those specified in table 3. |
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18.3 Thickness - The minimum wall thickness at any point shall not be more than 12.5 % under the nominal wall thickness specified. |
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Note 5 - The minimum wall thicknesses on in section of some of the available sizes are shown in Table X2. |
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19. Lengths |
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19.1 Pipe lengths shall be in accordance with the following regular practice:
19.1.1 The lengths required shall be specified in the order, and
19.1.2 No jointers are permitted unless otherwise specified.
19.1.3 If definite lengths are not required pipe may be ordered in single random lengths of 16 to 55ft (4.8 to 6.7 m) with 5% 12 to 16ft (3.7 to 4.8m), or in double random lengths with a minimum average of 35 ft (10.7m) and a minimum length of 22ft with 5% 16 to 22ft. |
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20. Finish |
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20.1 The pipe manufacturer shall explore sufficient number of visual surface imperfections to provide reasonable assurance that they have been properly evaluated with respect to depth. Exploration of all surface imperfections is not required but may be necessary to assure compliance with 20.2 |
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20.2 Surface imperfections that penetrate more than 12 ½ % of the nominal wall thickness or encroach on the minimum wall thickness shall be considered defects. Pipe with such defects shall be given one of the following dispositions:
20.2.1 The defect may be removed by grinding proving that the remaining wall thickness is withing specified limits.
20.2.2 Repaired in accordance with the pair wielding provisions of 20.6
20.2.3 The section of pipe containing the defect may be cut off within the limits of requirements on length
20.2.4 Rejected. |
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20.3 To provide a workman link finish any basis for evaluation conformance with 20.2 the pipe manufacturer shall remove by grinding the following non injurious imperfections :
20.3.1 Mechanical marks, abrasions (Note 6) and pits, any of which imperfections are deeper than 1/16 in. (1.58mm)
20.3.2 Visual imperfections commonly referred to as scabs, seams, laps, tears, or silvers found by exploration in accordance with 20.1 to be deeper than 5% of the nominal wall thickness. |
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20.4 At the purchaser’s discretion, pipe shall be subjected to rejection if surface imperfections acceptable under 20.2 are not scattered, but appear over a large area in excess of what is considered a work manlink finish. Disposition of such pipe shall be a matter of agreement between the manufacturer and the purchaser. |
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20.5 When imperfections or defects are removed by grinding, a smooth curved surface shall be maintained, and the wall thickness shall not be decreased below that permitted by this specification. The outside diameter at the point of grinding may be reduced by the amount so removed.
20.5.1 Wall thickness measurements shall be made with a mechanical caliper or with a properly calibrated nondestructive testing device of appropriate accuracy. In case of dispute, the measurement determined by use of the mechanical caliper shall govern. |
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20.6 Weld repair shall be permitted only subject to the approval of the purchaser and in accordance with specification A 530. |
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20.7 The finished pipe shall be reasonably straight. |
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Note 6 - Marks and abrasions are defined as cable marks, dings, guide marks, roll marks, ball scratches, scores, die marks, etc. |
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