FINAL DRAFT UGANDA 
STANDARD  
  FDUS 928-3
First Edition
2012-mm-dd
 
 
 Reference numbe r
FDUS 928-3: 2012
© UNBS 2012 
  
Threaded unplasticized polyvinyl chloride (PVC-U) water well 
filter pipes and casings — Part 3: DN 250 to DN 400 pipes with 
trapezoidal  
 FDUS 928-3: 2012 
ii © UNBS 2012 – All rights reserved
 Compliance with this standard does not, of itself confer immunity from legal obligations 
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible for its correct application  
© UNBS 2012  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, in cluding photocopying and microfilm, without prior written 
permission from UNBS. 
Requests for permission to reproduce this document should be addressed to 
The Executive Director 
Uganda National Bureau of Standards 
P.O. Box 6329 
Kampala  
Uganda 
Tel: 256 414 505 995 
Fax: 256 414 286 123 
E-mail: unbs@infocom.co.ug  FDUS 928-3:2012 
© UNBS 2012 – All rights reserved  iii
 Contents Page 
Foreword  .............................................................................................................................. .............................. iv  
1 Scope  .............................................................................................................................. ........................ 1  
2 Normative references  ............................................................................................................................ 1  
3 Dimensions, designation, mass and pattern of perforations  ..................................................................... 1  
4 Materials  ............................................................................................................... Error! Bookmark not defined.  
5 Requirements  .............................................................................................................................. ..................... 4  
5.1 General  .............................................................................................................................. ............................ 4  
5.2 Physiological safety  .............................................................................................................................. ....... 4  
6 Screw thread  .............................................................................................................................. ...................... 4  
7 Ring seals  .............................................................................................................................. ........................... 6  
Other relevant standards  ....................................................................................... Error! Bookmark not defined.  
 
 FDUS 928-3: 2012 
iv © UNBS 2012 – All rights reserved
 Foreword 
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry  of Tourism, Trade and 
Industry established by the Act of Parliament of 198 3, of the Laws of Uganda.  UNBS is mandated to co-
ordinate the elaboration of standards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex A limentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT/SPS Agr eements of the World Trade Organisation (WTO). 
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a gi ven field or area and consists of representatives of 
consumers, traders, academician s, manufacturers, governme nt and other stakeholders. 
Draft Uganda Standards adopted by the Technical Committ ee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Standards by the National Standards Council.  
Committee membership 
The following organizations were represented on t he Building and civil engineering standards Technical 
Committee (UNBS/TC 3), during the development of this standard: 
• Kyambogo University 
• Makerere University 
• Ministry of Works and Transport 
• Metro Plastics 
• Multiple Industries Ltd 
• Uganda National Bureau of Standards 
 
 FINAL DRAFT UGANDA STANDARD FDUS 928-3: 2012
 
© UNBS 2012– All rights reserved  1
 Threaded unplasticized polyvinyl chloride (PVC-U) water well 
filter pipes and casings — Part 3: DN 250 to DN 400 pipes with 
trapezoidal thread  
1 Scope 
This Final Draft Uganda Standard specifies dimensions and requirements for DN 250 to DN 400 unplasticized 
polyvinyl chloride 
(PVC-U) filter pipes and casings with tra pezoidal thread for use in well construction  
2 Normative references 
The following referenced documents are indispensable for the application of this document. For dated 
references, only the edition cited applies. For undated references, the latest edition of the referenced 
document (including any amendments) applies. 
ISO 261 ISO metric trapezoidal screw threads – Thread profiles  
ISO 178, Determination of the flexural properties of plastics  
ISO 179, Plastics – Determination of Charpy impact strength  
ISO 527-2, Determination of tensile properties of plastics – Part 2: Test conditions for moulding and extrusion 
plastics  
ISO 11664-1, Colour chart – System based on the 2° standard colorimetric observer 
3 Dimensions, designation, mass and pattern of perforations 
l2 is the effective pipe length after assembly, l1 being equal to l2 plus the thread length l3 
  
 
  FDUS 928-3: 2012 
2 © UNBS 2012 – All rights reserved
 
 
 
Designation of a DN 300 PVC-U filter pipe with trapezoidal thread (F), with a wall thickness, s, of 14.5 mm, an 
effective length, l 2, of 3 000 mm and a perforation width, w, of 2 mm: 
Pipe FDUS 928-3 – F 300 × 14.5 × 3 000/2 
Designation of a DN 300 PVC-U casing with trap ezoidal thread (V), with a wall thickness, s, of 14.5 mm and 
an effective length, l2, of 2 000 mm: 
Pipe FDUS 928-3 – V 300 × 14.5 × 2 000 
 
 
 FDUS 928-3: 2012 
© UNBS 2012 – All rights reserved  3
 
 
 
 FDUS 928-3: 2012 
4 © UNBS 2012 – All rights reserved
 Table 3 — Material requirements 
Property Unit Required value Testing as in 
Impact strength - 10 % max. **) *) 
Notched impact strength kJ/ m2 Over 5 ISO 179 
Yield point N/ mm2 45 to 55 ISO 527-2 
Elastic modulus N/mm2 2500 to 3000 ISO 178 
*) The method used shall be based on ISO 179. 
**) Not more than 10 % of the specimens shall fracture. 
 
4 Requirements 
4.1 General 
The internal and external surfaces of pipes and casings shall be smooth, free from blistering, sink marks, and 
any inhomogeneities likely to impair their performance. Slight irregularities such  as shallow grooves are 
permitted provided the nominal wall thickness is not  less than the specified value at any point. 
Pipes and casings should be dyed blue throughout (for example, colour ISO 11664-1 – 17,3 : 5,1 : 2,5, 
corresponding to colour RAL 5015 as in Farbregister RAL 840 HR [1]), slight deviations from this colour being 
permitted.  
Subject to agreement, filter pipes may be given a gravel jacket which shall overlap the perforated section by at 
least 20 mm at either end. 
4.2 Materials 
Filter pipes and casings shall be made of PVC-U as sp ecified in Table 3, without fillers. The type and 
quantities of vinyl chloride polymers, stabilizers, lubricants and other additives (for example, pigments) to be 
added to the moulding compound shall be at the manufac turer’s discretion. Moulding compounds of unknown 
composition shall not be used. 
The manufacturer shall, on request, provide a type 2.1 inspection document. 
4.3 Physiological safety 
Pipes, casings, fittings and jointing materials shall not release harmful substances into the drinking water in 
such amounts as are likely to affect the taste, odour or colour of the water. Algal or microbial growth in the 
water shall not be stimulated. 
5 Screw thread 
The thread used shall have a profile (except for thread height and flank clearance) as specified in ISO 724 
and ISO 261.  
Other design details are left unspecified FDUS 928-3 : 2012 
© UNBS 2012 – All rights reserved  5
 
 
 
 
 
Designation of a flat metric trapezoidal thread (TR) for filter pipes and casings with an outside diameter of 280 
mm, with flank clearance and a 12 mm pitch: 
Thread FDUS 928-3 – TR 280 × 12 
1) A 0,5  × 45° chamfer may be substituted for radius R 0,5.  
 
 FDUS 928-3: 2012 
6 © UNBS 2012 – All rights reserved
 6 Ring seals 
Ring seals shall be continuous and made of acrylonitr ile butadiene rubber (NBR) of (70 ± 5)° Shore A 
hardness complying with the requirements specified in  the relevant KTW-Empfehlungen [2]. Fitting of seals 
shall be in accordance with the manufacturer’s instructions.  
 
Designation of a ring seal for a DN 300 screwed pipe: 
Seal FDUS 928-3 – 300  
 FDUS 928-3: 2012 
© UNBS 2012 – All rights reserved  7
 Bibliography 
1) DIN 2000 Central drinking water supply syst ems – Basic water quality requirements – Design, 
construction and operation of systems 
2) DIN 4922-1 Water well steel filter pipes with  slotted perforations for connection by straps 
3) DIN 4922-2 DN 100 to DN 500 water well threaded steel filter pipes 
4) DIN 4922-3 DN 500 to DN 1000 water well flanged steel filter pipes 
5) DIN 4925-1 Threaded unplasticized polyvinyl chloride (PVC-U) water well filter pipes and casings 
– DN 35 to DN 100 pipes with Whitworth pipe thread 
6) DIN 4925-2 Threaded unplasticized polyvinyl chloride (PVC-U) water well filter pipes and casings 
– DN 100 to DN 200 pipes with trapezoidal thread  
 
 
  
 
 
 
 
  
 
 
  
 
 
 
 
 
 FDUS 928-3: 2012 
8 © UNBS 2012 – All rights reserved
  
 
 FDUS 928-2: 2012 
© UNBS 2012– All rights reserved  9
 Certification marking 
Products that conform to Uganda standards may be  marked with Uganda National Bureau of Standards 
(UNBS) Certification Mark shown in the figure below.  
The use of the UNBS Certification Mark is gove rned by the Standards Act, and the Regulations made 
thereunder. This mark can be used only by those licens ed under the certification mark scheme operated by 
the Uganda National Bureau of Standards and in co njunction with the relevant Uganda Standard. The 
presence of this mark on a product or in relation to a product is an assurance that the goods comply with the 
requirements of that standard under a system of supervision, control and  testing in accordance with the 
certification mark scheme of the Uganda National  Bureau of Standards. UNBS marked products are 
continually checked by UNBS for conformity to that standard.  
Further particulars of the terms and conditions of  licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
 FDUS 928-2: 2012
 
ICS 23.040.20  
Price based on es 
© UNBS 2012 – All rights reserved  
  nn pag