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1、INTERNATIONAL STANDARD IS0 3821 Third edition 1998-l l-01 Gas welding equipment - Rubber hoses for welding, cutting and allied processes Mat - arc welding under the protection of an inert or active gas; - processes allied to welding and cutting. This International Standard does not apply to hoses us
2、ed for high pressure acetylene more than 0,15 MPa (1,5 bar). 2 Normative References The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All Standards are
3、 subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 37: 1994
4、, Rubber, vulcanized or thermoplastic - Determination of tensile stress-strain properties. IS0 188: 1998, Rubber, vulcanized or thermoplastic - Accelerated ageing and heat-resistance tests. IS0 471: 1995, Rubber - Temperatures, humidities and times for conditioning and testing. IS0 1307:1992, Rubber
5、 and plastics hoses for general-purpose industrial applications - Bore diameters and tolerances, and tolerances on length. 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 20:19
6、:50 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 3821:1998(E) 0 IS0 IS0 1402:1994, Rubber and plastics hoses and hose assemblies - Hydrostatic testing. IS0 1746:-l ), Rubber or plastics hoses and tubing - Bending tests. IS0 181 7:-2), Rubber, vulcanized - Determinati
7、on of the effect of liquids. IS0 4080:1991, Rubber and plastic hoses and hose assemblies - Determination of permeability to gas. IS0 4671 :-3), Rubber and plastics hose and hose assemblies - Methods of measurement of dimensions. IS0 4672:1997, Rubber and plastics hoses - Sub-ambient temperature flex
8、ibility tests. IS0 7326:1991, Rubber and plastics hoses - Assessment of ozone resistance under static conditions. IS0 8033:1991, Rubber and plastics hose - Determination of adhesion between components. IS0 11114-3:1997, Transportable gas cylinders - Compatibility of cylinder and valve materials with
9、 gas contents - Part 3: Autogenous ignition test in oxygen atmosphere. 3 Materials 3.1 Construction The hose shall consist of: - a rubber lining of a minimum thickness of 1,5 mm; - reinforcement applied by any suitable technique; - a rubber cover of a minimum thickness of 1 mm. 3.2 Manufacture The l
10、ining and cover shall be of uniform thickness and free from holes, porosity and other defects. 4 Dimensions and tolerances 4.1 Internal diameter The internal diameter of the hoses shall be in accordance with the dimensions shown in table 1. 4.2 Concentricity (total indicated reading) The concentrici
11、ty of the hose, measured in accordance with IS0 4671, shall be in accordance with the values given in table 1. 4.3 Cut lengths and tolerances The tolerances for cut lengths shall be in accordance with IS0 1307. 1) To be published. (Revision of IS0 1746:1983) 2) To be published. (Revision of IS0 1817
12、:1985) 3) To be published. (Revision of IS0 4671:1984) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 20:19:50 MDTNo reproduction or networking permitted without license from IH
13、S -,-,- 0 IS0 IS0 3821 :1998(E) Table 1 - Nominal bores, internal diameters, tolerances and concentricity Nominal bore Internal diameter Tolerance Concentricity max. (mm) (mm) (mm) 4 4 5 5 f 0,55 1 673 6,3 a a + 0,65 10 10 1,25 12,5 12,5 + 0,7 16 16 20 20 f 0,75 25 25 32 32 *l 1,5 40 40 +z 1,25 50 5
14、0 NOTES 1 The tolerances and internal diameters (excluding nominal bore of 20) do not comply with table 1 of IS0 1307:1992. 2 For intermediate dimensions, numbers should be chosen from the R20 series of preferred numbers with tolerances as for the next larger internal diameter shown in table 1. Copy
15、right International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 20:19:50 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 3821:1998(E) 0 IS0 5 Physical properties of lin
16、ing and cover 5.1 Tensile strength and elongation at break The rubber used in the lining and cover shall, when tested in accordance with IS0 37, have a tensile strength and elongation at rupture not less than the values given in table 2. Table 2 -Tensile strength and elongation at rupture Rating lin
17、ing Tensile strength MPa 5 Elongation at break % 200 cover 7 250 5.2 Accelerated ageing After ageing for 7 days at a temperature of 70 “C as described in IS0 188 (air oven), the tensile strength and elongation at rupture of the lining and cover shall not decrease from the values given in table 2 by
18、more than 25 % for the tensile strength and 50 % for elongation at rupture. 5.3 Non-ignition requirement for oxygen hoses Non-ignition test shall be carried out either according to IS0 11114-3 or annex A. When tested according to IS0 11114-3 the initial conditions should be set at 2 MPa (20 bar) (am
19、bient temperature) and the autogenous ignition temperature should be higher than 150 “C. When tested by the method described in annex A, three samples of the lining shall remain in the apparatus at a constant temperature of 360 “C to 365 “C for 2 min without ignition. If more than one of the samples
20、 show evidence of ignition in less than 2 min, the hose shall be considered not to comply. If only one sample shows evidence of ignition in less than 2 min, three further samples shall be prepared and tested. If any of the three samples in this second series shows evidence of ignition in less than 2
21、 min, the hose shall be deemed not to comply. 5.4 Resistance to liquids 5.4.1 Resistance to acetone and dimethylformamide (DMF) for acetylene hoses and all fuel gas hoses A sample of the lining, when immersed in the test solvent at standard laboratory temperature as defined in IS0 471 for 70 h, shal
22、l not increase in mass by more than 8 % when calculated in accordance with the method in IS0 1817. 5.4.2 Resistance to n-pentane for LPG4) hoses, MPS5) hoses and all fuel gas hoses A sample of the hose lining, when tested as described in annex B, shall show n-pentane absorbed not exceeding 15 % and
23、n-pentane extractable matter not exceeding 10 %. 4) LPG: Liquefied petroleum gases 5) MPS: Methylacetylene-propadiene-mixtures 4 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 2
24、0:19:50 MDTNo reproduction or networking permitted without license from IHS -,-,- 0 IS0 IS0 3821 :1998(E) 6 Requirements 6.1 Hydrostatic requirements The hose, when tested in accordance with IS0 1402, shall meet the requirements of table 3. Rating nominal bore maximum design working pressure Table 3
25、 - Hydrostatic requirements Light duty Normal duty s 6,3 all sizes 1 MPa (10 bar) 2 MPa (20 bar) proof pressure I 2 MPa (20 bar) I 4 MPa (40 bar) minimum burst pressure 3 MPa (30 bar) 6 MPa (60 bar) change in length at maximum design working pressure -c 5 % change in diameter at maximum design worki
26、ng pressure + 10% 6.2 Adhesion When tested in accordance with IS0 8033 using the type 2 or type 4 test piece, the minimum adhesion between adjacent components shall be 1,5 kN/m. 6.3 Flexibility When tested in accordance with IS0 1746 at standard laboratory temperature as defined in IS0 471 using a d
27、iameter of curvature, C, of ten times the internal diameter (with a minimum of 60 mm), and a coefficient of deformation, K, of not less than 06, there shall be no kink in the curved portion of the hose. 6.4 Low-temperature flexibility When tested in accordance with IS0 4672:1997, method B, at (- 25
28、+ 2) “C, using a diameter of curvature of ten times the internal diameter (with a minimum of 80 mm), the hose shall show no signs of leaks when subjected to the proof pressure (carried out at ambient temperature) stated in table 3. 6.5 Resistance to incandescent particles and hot surfaces The cover
29、of the hose shall have sufficient resistance to contact with incandescent particles and hot surfaces. To meet this requirement, the test piece shall resist for 60 s the test conditions given in annex C, without leaking. 6.6 Ozone resistance When tested in accordance with IS0 7326:1991, method 1, the
30、 cover, under two times magnification, shall show no evidence of cracking. 6.7 Permeability to gas for LPG hoses, MPS hoses and all fuel gas hoses When tested in accordance with IS0 4060 using a test gas of 95 % propylene at cylinder pressure approximately 0,6 MPa (6 bar) and standard laboratory tem
31、perature of 23 “C as defined in IS0 471 the gas permeance shall not exceed 25 cm3/m/h, irrespective of internal diameter. 5 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 20:19:
32、50 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 3821:1998(E) 0 IS0 6.8 Requirements for twin hoses When using twin hoses, each, or both, of the hoses shall, after separation, conform to this International Standard. The separation of the hoses shall be commenced by me
33、ans of a knife. The hoses shall be manually dissociated (with a force between 5 daN and 10 daN) over a length of about 1 000 mm. The starting zone shall be discarded and then each of the hoses thus obtained, shall be submitted to the relevant tests in accordance with this International Standard and
34、shall meet its requirements. 7 Colour identification and marking 7.1 General The hose cover material shall be coloured throughout and marked as follows. 7.2 Colour identification In order to identify the gas for which the hose is to be used the hose cover shall be coloured as given in table 4. Hoses
35、 which comply with the requirements given in 5.4.1, 5.4.2 and 6.7 shall be coloured half red and half orange (one side red and one side orange) and can be used with all fuel gases given in table 4. In the case of twin hoses, each of the individual hoses shall be coloured and marked in accordance wit
36、h this International Standard. Table 4 - Colour coding and marking Gas I Colour of cover I acetylene and other combustible gases a (except LPG, MPS, natural gas, red methane) oxygen air, nitrogen, argon, CO, blue black LPG, MPS, natural gas, methane orange all fuel gases (included in this table) red
37、-orange a The manufacturer shall be consulted on the suitability of the hose for use with hydrogen. 7.3 Marking The hose cover shall be continuously and durably marked at least every 1 000 mm with the following information: - the number of this International Standard, i.e. IS0 3621; - the maximum de
38、sign working pressure in MPa and between parentheses in bar; - the nominal bore; - the manufacturers or suppliers mark (in the example given as XYZ); - the year of manufacture. EXAMPLE: IS0 3821 - 2 MPa (20 bar) - 10 - XYZ - 96 Copyright International Organization for Standardization Provided by IHS
39、 under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 20:19:50 MDTNo reproduction or networking permitted without license from IHS -,-,- 0 IS0 Annex A (normative) IS0 3821:1998(E) Method of test for non-ignition A.1 Apparatus The apparatus shown in figure
40、A.1 is required together with the following. A.1 .I heating furnace: 350 W, internal dimensions: 150 mm deep by 50 mm diameter. A.l.2 tubular sliding resistance: 190 Q to 200 R , with screw movement or an auto-transformer with continuously variable output voltage. A.l.3 calibrated flowmeter for oxyg
41、en: 0 to 5 Vmin at atmospheric pressure and 15 “C. A.l.4 nitrogen-filled mercury-in-glass thermometer: suitable for use at 150 mm immersion, graduated from approximately 300 “C to 400 “C in intervals of not more than 5 “C, the graduations to start not less than 200 mm above the bulb. A.2 Procedure I
42、nsert the ignition test apparatus, in its aluminium foil wrapping, into the electric furnace (A.1 .l). The purpose of the aluminium foil is to minimize radiant heat and to obtain a more uniform temperature distribution. Adjust the energy supply to the electric furnace with the variable resistance (A
43、.l.2) or auto-transformer so that a constant temperature of 300 “C to 365 “C is maintained with the oxygen flowing at (2 f 0,l) I/min. After cleaning by buffing, cut the sample of rubber lining for test into blocks of 8 mm3 to 10 mm3 of which no side shall be less than 1,3 mm nor greater than 2,5 mm
44、. When the furnace is at constant temperature, remove the sample holder, impale a sample block of the rubber lining under test on the tungsten point and replace the sample holder in the apparatus. It is necessary for this operation to be carried out quickly, so that cooling is reduced to a minimum.
45、The tungsten point should be kept clean and sharp. Retain the sample in the apparatus for at least 2 min and observe it carefully during this period, for evidence of ignition. Fumes may be observed but this shall not constitute evidence of ignition, which is normally accompanied by a flash and somet
46、imes by a small explosion. When ignition of a sample occurs, the temperature of the apparatus can rise and it is then essential that time be allowed in oreder to permit the temperature to return to the appropriate testing temperature. Test three samples consecutively. 7 Copyright International Organ
47、ization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 20:19:50 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 3821 :1998(E) 0 IS0 Dimensions in millimetres Constructed from borosilic
48、ate glass tubing of wall thickness: - 0,751 mm to 1,25 mm for a diameter of 6 mm to 9 mm; -1 mmto2mm for a diameter of 36 mm to 46 mm ,- 046kO.S -1 1 Oxygen outlet 2 Heat-resistant packing 3 Thermometer 4 Orifice 5 14/23 joints 6 Oxygen inlet 7 Aiuminium foil 8 Tungsten wire with a diameter of 0,7 mm tapered to a fine point and (20 + 0,5) mm long Figure A.1 -Apparatus for ignition tests on lining samples 8 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 20:19:50