1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. SABS 0120 : Part 5 Section L-1983 edium-pressure pipelines PART 5 : CONTRACT ADMINISTRATION SECTION L CONTENTS Page Number START OF CONSTRUCTION 1 Genera
4、l 1 1MMEDIATELY AFTER THE HANDING OVER OF THE SITE . 1 General 1 DURING CONSTRUCTION 1 Methods of Construction 1 General 1 Materials 1 . Insertion pieces for flanges 1 Steel pipes of nominal bore over 150 m 1 Trenches and trench bottoms 1 Pipelaying in general 1 . AC pipes with C1 detachable joints
5、2 . Concrete mix for ancillary works 2 Filling of trenches 2 Mortar mixing 2 Hydraulic test on individual joints . 2 Administration . 2 Shop welding of steel pipes 2 Verifying protection . 2 Corrosive soils . 2 . Filing of AC pipe ends 2 Concrete casing . 2 Tolerances 2 Bleeding of AC pipeline joint
6、s . 2 Dye-penetrant teat on welded steel pipe . 2 Leakage rates 3 . QUALITY CONTROL AND OTHER CONSIDERATIONS 3 General . 3 Disputes . 3 DRAWINGS Drawing L.5.1 . Example of Data Required at Start of Contract . 4 Drawing L-5.2 . Maximum Permissible Leakage Rates for 100 urn Diameter AC Pipeline under
7、Hydraulic . . Test at 0. 4 2. 3 MPa 5 Drawing L-5.3 . Maximum Permissible Leakage Rates for 100 . 1200 m AC Pipelines under Hydraulic Test at Pressures up to 3 MPa 6 First Revision March 1983 This section of the code supersedes SABS 0120 : Part S : Section L-1980 Approved by the COUNCIL OF THE SOUTH
8、 AFRICAN BUREAU OF STANDARDS SABS 0120 : E1art 5 Section L-1983 Medium-pressure pipelines SABS 1200 L : MEDIUM-PRESSURE PIPELINES NOTE: The clause number(s) given at the beginning or after the heading of a clause is/a.re, unless otherwise stated, the number(s) of the relevant clause(s) of SABS 1200
9、L. START OF CONSTRUCTION GENERAL. For the purposes of this part of the code contract administration starts with instructions to the contractor to comnence work as set out in Subclause 4.1 of Section 0. IMEDIATELY AFTER THE HANDING OVER OF THE SITE GENERAL. The engineer should provide the contractor
10、with adequate information about where pipelines are to be laid. He should state positively the distances from boundaries, fences, kerb lines, etc., and also the depths to which the contractor is to excavate. The information should be extensive enough (as indicated on Drawing L-5.1) to enable the con
11、tractor to program the contract t completion. Information sufficient only to enable him to commence excavation is not acceptable. DURING CONSTRUCTION METHODS OF CONSTRUCTION General. Pipes of the finest quality and complying with a standard specification can be ruined by improper handling and by imp
12、roper bedding and backfilling. tn calculating the strength of a pipeline, certain assumptions are made in the design criteria regarding trench width, type of bedding, and backfilling. Observance of the recommendations of 3.1.2 - 3.1.10 below will assist in the achievement of optimum conditions in pr
13、actice. iidance on methods of-construction generally shotd also be obtained from the Code of practice for the construction of fibre-reinforced cement pipelinesL. Materials (Subclause 3.1). All pipes used must comply with the relevant requirements of the appropriate standard swcification, must be pro
14、tected durinq transportation and handlinq from damaqe caused by impact, drbpping, etc and must-be inspected for defects immediately before laying. aulty pipes or pipes that have suffered such damage that their serviceability is affected must not be used in the work. Insertion Pieces for Flanges (Sub
15、clause 3.8.3). Insertion pieces for flanges should be made of a) rubber, in the case of small pipes (of diameter under 450 mm) that are subject to a maximum test pressure not exceeding 2,s MPa; and b) compressed asbestos or similar approved material in the case of medium size pipes (of diameter 450
16、- 750 m), large pipes (of diameter over 750 mm), and small pipes that are subject to a maxnmum test pressure exceeding 2,s HPa. Steel Pipes of Nominal Bore over 150 nun (Subclause 3.9.2.2). The Sa 21 finish specified is equnvalent to a surface profile of 30-60 Mm. Trenches and Trench Bottoms (Subcla
17、use 5.1.1). Where the pipe is to be bedded on a natural earth bed, the mechanical excavation of trenches should be stopped high enough above the final elevation on the bottom of the pipe to enable the pipe barrel to be laid on a fim undisturbed earth bed. If overdigqing occurs, all loosened earth sh
18、ould be remved and the trench bottom brought back to grade with well-compacted material. In rock or water-bearing earth or where a concrete or granular base is to be provided, excavation should be done to the depth below the pipe bottom required for the class and thickness of bedding that is to be u
19、sed. Particular care should be taken with earth which, though fim when trenched, may be rendered unstable by rain or by seepage from drainage lines or leaking water mains. Until the pipeline has been laid and backfilled, it is essential that the bottom of the trench should be kept sufficiently free
20、from water to enable the bedding to be prepared and the pipeline laid. In the case of Class B and Class C bedding this means the trench must be kept quite dry. The following precautions should be taken: a) Surface water should be controlled by the disposition of excavated material and the constructi
21、on of drainage channels in such a manner that they prevent surface water or stormwater from entering the trench. b) When ground water is present, an adequate side channel should be made in the trench bottom adjacent to one side of the trench, and provision should be made to drain the water away fxom
22、 this channel at a low point or to remove it by pumping. Backfilling should be properly compacted in layers the thickness of which depends on local conditions. Care should be taken to prevent water from entering backfilled trenches. Road surfaces should be reinstated promptly. C) Where the trench bo
23、ttom is in a saturated silt and well-pointing is too difficult or expensive, a crushed stone working floor covered with a geofabric (porous drainage membrane) should te provided under the bedding layer for the pipe. Pipelaying in General (Subclauses 5.1.1, 5.1.2, and 5.1.4.2). The contractor is resp
24、orsible for laying the pipeline in such a manner that, when completed, it complies with the specification and drawings and performs its designed function. To achieve this he should ensure that his pipelayers axe qualified and experienced. In particular a) the onus for detecting damaged pipes (Subcla
25、use 5.1.2 of SABS 1200 L) before they ares laid rests on the contractor, and b) deflection of joints at changes of grade (Subclause 5.1.4.2 of SABS 1200 L) should vary with the type of joint in use. See also Subclause 3.2.6 of Section L of Part 2 and Subclause 2.3 of Section L of Part 3 of the code
26、in regard to depth of excavation and cover. L) Published by the SA Fibre-Reinforced Cement Manufacturers Association, Braamfontein, September 1982. SABS 0120 : Part 5 Section L-1983 Mediumpressure pipelines AC Pipes with C1 Detachable Joints (Subclause 5.2). Special tapered wooden plugs provided by
27、the manufacturer should be used to roll the rubber rings on to the pipes when AC pipes with C1 detachable joints are jointed. Care should be taken that the rubber rings are not twisted. A gap of at least 10 mm should be left between the pipe ends when the joint is assembled. Pipes should be laid as
28、near as possible to line and grade before they are coupled together so that the gap will not be altered by excessive movement of the pipe during assembly. Care should be taken to maintain the minimum gap of 10 mm between the closest pints of the pipe ends on curves and not to exceed the maximum perm
29、issible deflection of 4 at any joint between pipes. Concrete Mix for Ancillary Works (Subclauses 5.4 and 5.5). The 15 MPa strength concrete specified can generally be obtained from a nominal 1:21:5 mix provided that the water/cement ratio is correct. Filling of Trenches (Subclause 5.1). Except when
30、Class A bedding is used (see SABS 1200 LB), trenches should be backfilled as soon as passible after the pipe has been laid. Selected fill should be placed carefully and without voids around and on top of the pipe in strict conformity with the requirements given for the class of bedding used and back
31、fill material should also be carefully placed. Compacting should be done uniformly so as not to displace the pipeline laterally or in a vertical direction. Where machines are used for backfilling and compaction, care should be taken not to subject the pipeline to loads greater than those for which i
32、t was designed. Where excess material does not have to be removed, it should be spread uniformly over the top of the trench fill, and provision should be made for cross drainage. Mortar Mixing (Subclause 5.8). Stale mortar should be removed from the mixing platform and the platform should be cleaned
33、 before each batch of mortar is prepared for mixing. Small quantities of the dry materials should be thoroughly mixed on the mixing platform before the water is added through a fine rose and the mixture should be turned over until the ingredients are thoroughly incorporated. Hydraulic Test on Indivi
34、dual Joints (Subclause 7.3). Reference should be made to Testing : Type 2 method given in the Code of practice for the construction of fibre-reinforced cement pipelinesa, for details of the equipment to be used and the procedures to be adopted for carrying out field hydraulic tests on pipelines bf l
35、arge diameter as pipelaying proceeds (see also 3.2.9 below, and Subclause 3.3.3 of Section L of Part 2 of the code). ADMINISTRATION Shop Welding of Steel Pipes (Subclause 3.4.4). Where so required by the contractor and allowed in terms of the project specification, the contractor should submit his p
36、roposal for an agreement on an approval test other than that given in API 1104. Such a proposal should be submitted in good tiw to enable an agreerwnt to be reached before any welding work is started. (See Subclause 2.l(b) of Section L of Part 2 of the code.) Verifying Protection (Subclause 3.9). Al
37、though corrosion protection adds to the cost of a pipeline, the protection specified has been selected in view of the particular liquid that is expected to flow through the pipeline. The contractor should ensure that the pipes are fully treated as specified and the engineer should satisfy himself th
38、at this has been done. Corrosive Soils (Subclause 3.9.6). Where the soil is highly corrosive, the following system, consisting of three basic components and reconrscnded for the protection of buried sections of a long (e.g. 10 km) steel pipeline of medium e.g. 450 mm) diameter, has been found from e
39、xperience to be satisfactory: a) An inhibitive petroleum jelly primer; b) a petroleum jelly inner wrap of average thickness 1.15 mm; and C) a PVC outer wrap of thickness 0,25 m. In addition to the wrapping of the pipeline itself, all components, mechanical joints, etc. should be protected by the use
40、 of an asbestos-filled petroleum jelly mastic (for packing out all irregular contours) and a PVC outer wrap. Filing of AC Pipe Ends (Subclause 5.3). Although many local authorities permit the filing of pipe-ends by their staff during routine maintenance, Subclause 5.3 of SABS 1200 L specifies that t
41、he contractor must use a fieldturning machine on cut ends of AC pipea. This is done to ensure the most efficient coupling, with the minimum of supervision, in a relatively high speed pipelaying operation by a third party whose responsibility for maintenance is generally limited to 12 months. From th
42、e point of view of both the contractor and the engineer this requirement is reasonable because its cost is negligible when compared to the cost of locating and rectifying a leak should any pipe ends have been so carelessly filed that leaks develop during testing or during the contractual maintenance
43、 period. In the case of the local authoritys own work, their staff, who may not be equipped with turning machines, are more interested in ensuring freedom from maintenance problems over the long term than in speed of repair, and can afford to spend time in perfecting each hand filed cut end. Concret
44、e Casinq (Subclause 5.4). Concrete casing is warranted, for example, when pipes are laid in unstable ground or at shallow depths. Tolerances (Clause 6). Both contractor and engineer must be conscientious in observing the tolerances specified for clearances inside structures. (See Subclauses 1.3.5, 1
45、.3.6, and 2.6.1 of Section L of Part 3 of the code.) Bleeding of AC Pipeline Joints (Subclause 7.3.1). It is difficult to prevent an occasional grain of sand from so lodging between the rubber ring and the wall of the pipe that leakage occurs. Leakage from this source may be rectified very easily by
46、 the sliding of a thin blunt steel blade between the rubber and the pipe. Dye-Penetrant Test on Welded Steel Pipe (Subclause 7.2.1). Should further details be required in regard to a) acceptable groups of penetrants and developers; b) compatibility of dye-penetrants and developers; C) testing method
47、s, reference may be made to Section V, Article 6, of the ASME boiler and pressure vessel code, 1977 edition3). 1) see p.1. 2) Bedding (pipes) 3) published by the merican Society of Mechanical Engineers. SABS 0120 z Part 5 Section 11983 Medium-pressure pipelines 3.2.9 Leakage Rates (Subclause 7.3.3).
48、 The maximum permissible leakage rates specified in Subclause 7.3.3 of SABS 1200 L have been derived from the results of research work and published papers4t dealing with permissible leakage of AC pipes under test. A raph and formula for the determination of the maximum permissible leakage rates are
49、 given in 1.50 4483) and the Code of practice for the construction of fibre-reinforced pipelines1). A copy of the graph is reproduced in Drawing L-5.2 and a graph showing the maximum permissible leakage rates for AC pipelines of nominal sizes 100-1200 mm is given in Drawing L-5.3. It should be noted chat saturation of concrete and AC pipelines should lead to lower rates of leakage during repeat tests. 4. QUALITY CONTROL AND OTHER CONSIDERATIONS 4.1 GENERAL. Apply the relevant recommendations of SABS 0157) to the construction of medium-pressure pipelines. 4.2 DISPUTES. See Sub
