1、BRITISH STANDARD BS 4508-4: 1977 Specification for Thermally insulated underground piping systems Part 4: Specific testing and inspection requirements for cased systems without air gap UDC 66.026 + 697.34:697.334:621.644.2:662.998BS4508-4:1977 This British Standard, having been prepared under the di
2、rectionof the Refrigeration, Heating and Air Conditioning Standards Committee, was published under the authority ofthe Executive Board on 30June1977 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference RHE/9 Draft for comment 75/70904 DC ISBN 0 580 09694
3、7 Cooperating organizations The Refrigeration, Heating and Air Conditioning Standards Committee, under whose direction this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Association of Consulting Engi
4、neers Association of Manufacturers of Domestic Electrical Appliances Boiler and Radiator Manufacturers Association Ltd British Combustion Equipment Manufacturers Association British Gas Corporation* British Mechanical Engineering Confederation British Refrigeration and Air Conditioning Association*
5、Building Services Research and Information Association Chartered Institution of Building Services Department of the Environment* Department of Health and Social Security* Electricity Supply Industry in England and Wales* Engineering Equipment Users Association* Heating and Ventilating Contractors As
6、sociation HEVAC Association Institute of Fuel Institute of Refrigeration Institution of Gas Engineers* Lloyds Register of Shipping Manufacturers Association of Radiators and Convectors Ministry of Defence* National Coal Board Society of British Gas Industries Water-tube Boilermakers Association The
7、organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: Asbestos Cement Manufacturers Association British Ceramics Research Association CBMPE Chemical Industries Associat
8、ion Combustion Engineering Association Department of Industry National Physical Laboratory Electrical Research Association EUROSOL-UK Association of Manufacturers of Mineral Fibre Insulation Fibre Building Board Development Organization Gypsum Products Development Association Process Plant Associati
9、on Spray Contracts Technical Committee Thermal Insulation Contractors Association Amendments issued since publication Amd. No. Date of issue CommentsBS4508-4:1977 BSI 11-1999 i Contents Page Cooperating organizations Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Definitions 1 4 General 1
10、 5 Type tests and inspections 1 6 Production inspections and tests 6 7 Test failure interpretation 6 8 System approvals 7 Appendix A Soil conductivity data 8 Figure 1 Joint testing apparatus to simulate actual operating conditions 8 Figure 2 Physical variations during a four-hour test cycle 9 Figure
11、 3 Test rig for the determination of system pressure-tightness 10 Publications referred to Inside back coverBS4508-4:1977 ii BSI 11-1999 Foreword This Part of BS 4508 has been prepared under the direction of the Refrigeration, Heating and Air Conditioning Standards Committee, and deals with requirem
12、ents for the independent certification of components and assemblies of components of cased, thermally insulated underground piping systems without air gap. Other Parts of the standard are as follows: Part 1: Steel cased systems with air gap; Part 2: Asbestos-cement cased systems with air gap; Part 3
13、: General requirements for cased systems without air gap. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from le
14、gal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 10, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment t
15、able on the inside front cover.BS4508-4:1977 BSI 11-1999 1 1 Scope This Part of BS 4508 specifies specific requirements for the testing, inspection and certification of pipe-in-pipe systems with an insulated service or product pipe enclosed in a pressure-tight casing; general requirements are specif
16、ied in Part 3. Data on soil conductivity are given in Appendix A. 2 References The titles of the publications referred to in this standard are listed on the inside back cover. 3 Definitions For the purposes of this Part of BS 4508 the definitions given in Part 3 apply. 4 General Testing and inspecti
17、on procedures are necessary to prove compliance with the performance specification, and include type testing and inspection in the laboratory and in the ground, together with production testing and inspection. Routine service inspections and tests are required to ensure continued compliance with the
18、 performance specification, and guidance on such tests is given in Appendix G of BS 4508-3:1977. 5 Type tests and inspections 5.1 Purpose and scope of the tests. Type test and inspection requirements that are common to all piping systems are specified in this Part of the standard. Type tests and ins
19、pections shall be carried out in the order given. 5.2 Type tests and inspections in the laboratory. The tests and inspections specified in5.2.1 to 5.2.6 shall be carried out on samples of the proposed service or product pipe. 5.2.1 Compatibility of pipes. The vendor shall be responsible for ensuring
20、, throughout the temperature range of the service pipe fluid, that the requirements specified in 5.2.1.1 and 5.2.1.2 are complied with. 5.2.1.1 Pipes protected against external corrosion. Where service or product pipes are protected by surface coatings against external corrosion, such coatings shall
21、 be chemically compatible with the insulating material. In such cases, a sample of pipe-in-pipe shall be prepared and after a 30-day period at the maximum temperature for which the system will be offered, the sample shall be examined for evidence of chemical reaction between the service pipe coating
22、 and the insulating material. Deterioration due to chemical reaction as judged by visual inspection shall constitute a failure of the system. NOTEDuring this test a certain amount of discoloration of the insulating material may be in evidence, even if the service pipe coating has not reacted chemica
23、lly with it; such discoloration is entirely an effect of temperature and the extent to which it shall be permitted to occur is stated in 5.2.3.2. 5.2.1.2 Pipes not protected against external corrosion. Where service or product pipes are not protected by surface coatings against external corrosion, t
24、he insulation proposed for the system shall provide such protection. In such cases, a sample of pipe-in-pipe shall be prepared and after a 30-day period at the maximum temperature for which the system will be offered, the sample shall be examined for evidence of corrosion on the service pipe. Any co
25、rrosion of this nature shall constitute a failure. 5.2.2 Pressure test on service or product pipe. The service or product pipe shall be subjected to a hydraulic pressure test of 1.5 times the maximum design pressure, at the system design temperature for which the system is offered, with a minimum ga
26、uge test pressure of 10 bar 1) . This pressure shall be maintained for a period of not less than 30 min. 5.2.3 Tests on insulating material. The tests and inspections specified in 5.2.3.1 to 5.2.3.4 shall be carried out on samples of the proposed insulating material. 5.2.3.1 Thermal conductivity or
27、thermal conductance. The thermal conductivity or thermal conductance of the proposed insulating material shall be tested in accordance with BS 874 and compared with the specification. For a typical size of pipe-in-pipe offered, calculations shall be made, using the calculation method shown in 7.4 e)
28、 of BS 4508-3:1977, to ensure that any casing material temperature limitation is not exceeded, and in no instance shall the casing temperature exceed 30 C. In no case shall the thermal conductivity or thermal conductance exceed that declared in the specification (see Appendix B of BS 4508-3:1977). T
29、he thermal conductivity or thermal conductance shall be obtained from the appropriate test method specified in BS 874. 1) 1 bar = 10 5N/m 2= 100 kPa.BS4508-4:1977 2 BSI 11-1999 5.2.3.2 Heat test. A sample length of pipe-in-pipe shall have heat applied to the service pipe to obtain a temperature 10 C
30、 in excess of the maximum fluid temperature specified. Discoloration of the insulating material shall stabilize at a radial distance of not greater than 5 mm from the service pipe after a period of 1 month. The insulation during this test shall in no way indicate thermal or mechanical deterioration.
31、 5.2.3.3 Physical properties. Samples of the proposed insulation shall be tested in accordance with BS2972 or BS 4370, as appropriate, to confirm the physical properties as declared in Appendix B of BS4508-3:1977. 5.2.3.4 Test for the action of fungi and bacteria. Samples of the proposed insulating
32、material shall be tested in accordance with ISO/R 846 in order to determine the behaviour of the material under the action of fungi and bacteria. (Levels of acceptance to be specified.) 5.2.4 Tests on pipe-in-pipe samples. The tests and inspections specified in 5.2.4.1 to 5.2.4.3 shall be made on sa
33、mples of the pipe-in-pipe including joints and fittings. 5.2.4.1 Preparation. Samples of the proposed casing and jointing materials shall be prepared and tested in accordance with 5.3.5. 5.2.4.2 Impact test. Samples of the proposed casing material shall be tested for impact strength in accordance wi
34、th method 306 of BS 2782:1970, as appropriate. 5.2.4.3 Resistance to ultra-violet light. The casing material, joints and fittings shall be protected against ultra-violet light degradation, this protection being sufficient for the period prior to backfilling. 5.2.5 Tests on field closure joints. The
35、test specified in 5.2.5.1 to 5.2.5.3 shall be carried out on at least one field closure joint by means of a test tank. Two samples shall be provided, one for the joint test (see5.2.5.2) and another for the bulkhead test (see5.2.5.3). The pipe-in-pipe shall pass through the tank walls, without restra
36、int on movement, by using a standard mechanical gland. A typical arrangement for the test tank is shown in Figure 1. 5.2.5.1 Test facilities 5.2.5.1.1 Dimensions of test pipe. The test pipe shall comprise a straight 2 m length of 50 mm service pipe with standard insulation and casing incorporating a
37、 field closure joint. 5.2.5.1.2 Tank water temperature. Provision shall be made for the tank water temperature to be varied between 10 C approximately and 30 C maximum, this variation being made in either direction at the rate of 20 C/h, and also for it to be controllable at either of the two above
38、mentioned limiting temperatures for a minimum period of 1 h. 5.2.5.1.3 Tank water pressure. The required tank pressure range shall be 0.1 bar (gauge) to 1.5 bar (gauge) and shall be capable of being varied from minimum to maximum in 10 min or less and be controllable at both of the above mentioned p
39、ressures. 5.2.5.1.4 Service pipe temperature. The temperature of the service pipe shall be capable of being varied between 10 C 2)and the maximum fluid temperature of the system (which shall be that specified in B.2.9 of BS 4508-3:1977), plus an excess of 10 C on the latter for the test purposes. It
40、 shall be controlled at either of these limits for a minimum period of 1 h. The pipe may be heated and cooled by a wet method of passing water through it or by a dry method of inducing an electric current into the pipe and cooling with air. 5.2.5.1.5 Service pipe longitudinal movements. Provision sh
41、all be made on the testing rig to move the service pipe in such a way that an oscillatory movement of 5 mm relative to the casing is achieved. This is done to simulate expansion and contraction on a larger system. 5.2.5.1.6 Indication of water ingress. Equipment giving an indication of the ingress o
42、f water into the joint shall be employed. When using the dry method, early ingress of water can be noted by the decrease in the electrical resistance between the service pipe and the water in the test tank, or by the increased length of time taken to reach the service pipe maximum temperature for th
43、e same current setting. The temperature should be measured with a thermocouple near the closure joint. Earlier indications may not be possible in the wet method. 5.2.5.1.7 Moisture content. Equipment for checking insulation moisture content shall be provided, for example, by weighing. 5.2.5.1.8 Vehi
44、cle loading simulation. Where the system is liable to be affected by vehicle loads and vibrations these effects should be simulated 3) . 2) The 10 C minimum figure is selected as being mains water temperature. 3) At present there is no established test requirement for vehicle loading, and a suitable
45、 test should be agreed between the purchaser and the vendor.BS4508-4:1977 BSI 11-1999 3 5.2.5.2 Test procedure (joints) 5.2.5.2.1 Water temperature (see Figure 2). The test shall commence with the tank water at 10 C approximately and cycling shall continue in the following manner: a) 1 h at 10 C app
46、roximately; b) 1 h heating period to 30 C maximum; c) 1 h at 30 C maximum; d) 1 h cool down to 10 C approximately. 5.2.5.2.2 Tank water pressure (see Figure 2). The test shall commence with the tank water pressure at0.1 bar (gauge) and cycling shall continue in the following manner: a) immediate app
47、licational pressure to 1.5 (gauge) (10 min maximum); b) 1 h at 1.5 bar (gauge); c) immediate drop in pressure to 0.1 bar (gauge); d) 2 h at 0.1 bar (gauge). 5.2.5.2.3 Service pipe temperature (see Figure 2). The test shall commence with the service pipe at10 C and cycling shall be synchronized with
48、the tank water temperature to vary in the following manner: a) 1 h at 10 C; b) 1 h heating period to the maximum fluid temperature specified plus 10 C; c) 1 h at the maximum fluid temperature specified plus 10 C; d) 1 h cool down to 10 C. 5.2.5.2.4 Service pipe longitudinal movement (seeFigure 2). T
49、he test shall commence with the service pipe in the normal or neutral position and cycling shall be synchronized with the changing service pipe temperature as follows: a) hold with zero movement for 1.5 h approximately; b) 10 mm/h longitudinal movement in one direction for 0.5 h (5 mm displacement); c) hold at a displacement of 5 mm for 1 h; d) return to normal or neutral position in 0.5 h. 5.2.5.2.5 Total test time. The successful completion of 108 cycles each of 4 h (based on tank temperature) will show that the joint
