Page images
PDF
EPUB

per roll

per 100

(IV) STANDARD WEIGHT, DIMENSIONS AND VARIATIONS Weights, Dimensions and Yardage 13. The tape shall conform to the following requirements: Nominal Minimum

Minimum weight net weight

length Width Thickness

per pound in. in.

lb.

rolls lb. (a) yd. (a) 1⁄2 0.015 14 25

82 34 0.015 1/2 50

55 1 0.015 12 50

41 11/2 0.015

1 or 1/4 100 or 125 2 0.015 192 150

20 (a) Exclusive of core, wrapping and box. Measurement of Thickness

14. The thickness shall be measured with a micrometer graduated to 0.001 inches, having a circular foot, 0.24 to 0.26 inches in diameter and with a pressure on the specimen of not less than 8 ounces nor more than 10 ounces. Four measurements shall be taken at random in a length of not less than 3 feet and no result shall be outside the limits prescribed. Permissible Variations

15. The width shall not vary from the specified value by more than 3-inch. The thickness shall not vary from the specified value by more than 0.002 inch.

(V) PACKING AND MARKING Packing

16. Each roll shall be wrapped in paraffined paper or inetal foil and enclosed in a suitable box. The wrapping shall be secure and shall thoroughly protect the contents. Marking

17. Each box shall be marked with the name of the manufacturer or a trade mark together with the nominal width and weight of the tape.

(VI) INSPECTION AND REJECTION Time of Inspection

18. The tape shall be inspected and tested within four weeks from the date of delivery. Retests and Rejections

19. If the tape fails in any one test of those prescribed in these specifications, two additional specimens shall be taken and submitted to that test. If either of these two additional specimens fails, the lot of tape represented by that sample shall be rejected.

RAILROAD SPECIFICATIONS FOR RUBBER INSULATING

TAPE Material Covered

1. These specifications cover rubber insulating tape to be used for insulating joints in electric wires and cables.

(1) MANUFACTURE Compound

2. The tape shall be a rubber compound which shall be well, evenly and smoothly calendered in sheets, then wound tightly on a mandrel with a separator interposed between adjacent layers and cut into rolls of uniform width. Separator

3. The separator shall be of glazed cotton or linen cloth or parchment paper and shall be attached to and cover the outer side of the tape. When unwound from the original roll it shall show no undue tendency to stick to the rubber.

a

(II) CHEMICAL PROPERTIES AND TESTS Composition

4. The tape shall be a rubber compound containing not less than 30 per cent. of the best quality Hevea rubber, not more than one per cent. of free sulphur and not more than 4 per cent. of waxy hydrocarbons.

The remainder shall consist only of suitable dry inorganic mineral fillers. The compound shall contain no reclaimed rubber, substitutes or organic matter other than herein above specified. All percentages shall be based on the weight of the original compound. Chemical Analysis

5. If an analysis of the compound is made, it shall be carried out in accordance with the Joint Rubber Insulation Committee's procedure.

(III) PHYSICAL PROPERTIES AND Tests Tensile Strength

6. (a) The tensile strength of the tape shall be not less than 300 1b. per sq. in.

(b) The tests shall be made with a power driven, pendulum-type tension testing machine; the initial distance between the jaws shall be 3 in. and the rate of separation of the jaws shall be 20 in. per minute. The width of the test specimen shall be 0.5 in.

(c) Three specimens of each sample free from visible flaws shall be tested. The average result shall be taken as the tensile strength.

(d) The temperature of the room shall be not lower than 18 deg. Centigrade (65 deg. Fahr.) nor higher than 32 deg. Centigrade (90 deg. Fahr.) and the samples shall have been kept within these temperature limits for at least 30 minutes previous to the time of testing. Dielectric Strength

7. Two brass ball sphere electrodes two cm. in diameter shall be brought so close together that the sample of tape can be just moved between them. The tape shall withstand without puncture for 5 minutes the application of an alternating potential of 10,000 volts (r.m.s. value) at a frequency not exceeding 65 cycles per second, applied to the spherical electrodes.

Fusion

8. The tape when wrapped to a thickness of 14-in. and heated to a temperature of 65.5 deg. Centigrade (150 deg. Fahr.) for 20 minutes shall fuse into a homogeneous mass. Test Samples

9. One roll for each 250 rolls shall be taken at random for test. At least 2 ft. of the outer layers shall be removed and discarded before taking specimens for test.

(IV) STANDARD WEIGHTS, DIMENSIONS AND VARIATIONS Thickness, Weight and Yardage 10. The tape shall conform to the following requirements: Nominal Minimum

Minimum weight net weight

length Width Thickness

per pound in. in.

Ib.

rolls Ib. (a) yd. (b) 12 0.035 12 50

2272 34 0.035 12 50

15 1 035 1 100

1174 (a) Exclusive of core, wrapping and box. (b) Exclusive of core, wrapping, box and separator.

per roll

per 100

Permissible Variations

11. The width shall not vary from the specified value by more than 3z-in. The thickness shall not vary from the specified value by more than 0.003 in.

Measurement Thickness

12. The thickness shall be measured with a micrometer graduated to 0.001 in. having a circular foot, 0.24 to 0.26-in, in diameter and with a pressure on the specimen of not less than 8 oz. or more than 10 oz. Four measurements shall be made at random in a length of not less than 3 ft. and no measurement shall be outside the limits prescribed in Sections 10 and 11.

(V) PACKING AND MARKING Packing

13. Each roll shall be wrapped in paraffined paper or metal foil and enclosed in a suitable box. The wrapping shall be secure and shall thoroughly protect the contents. Marking

14. Each box shall be marked with the name of the manufacturer or trade mark and the noninal width and weight of the tape.

(VI) INSPECTION AND REJECTION Time of Inspection

15. The tape shall be tested and inspected within four weeks of the date of delivery. Retest and Rejection

16. If the tape fails in any one test of those prescribed in these specifications, two additional specimens shall be taken and submitted to that test. If either of these two additional specimens fails, the lot of tape represented by that sample roll shall be rejected.

« PreviousContinue »