ICS  77.140.75  
 
Reference number  
DRS 263 -3: 2020  
© RSB 2020  
  
 RWANDA 
STANDARD  DRS  
263-3 
Second edition  
2020 -06-dd 
 
Steel tubes for non -pressure purposes — 
Specification  
Part 3: Steel tubes for rolls for conveyor 
belt idles  
   
DRS 263 -3: 2020  
©RSB 2020 - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in i ndustries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB 2020  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
Requests for permission to reproduce this document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 263 -3: 2020  
iii                ©RSB 2020 - All rights reserve d 
 Cont ents Page 
Foreword  ................................ ................................ ................................ ................................ .............................  v 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Requirements  ................................ ................................ ................................ ................................ .........  1 
4.1 Grade and type  ................................ ................................ ................................ ................................ ...... 1 
4.1.1  Type  ................................ ................................ ................................ ................................ ........................  1 
4.1.2  Grade  ................................ ................................ ................................ ................................ ......................  2 
4.2 Material  ................................ ................................ ................................ ................................ ...................  2 
4.3 Physical properties  ................................ ................................ ................................ ...............................  2 
4.4 Dimensions  ................................ ................................ ................................ ................................ ............  2 
4.4.1  Outside diameter and wall thickness  ................................ ................................ ................................ .. 2 
4.4.2  Length  ................................ ................................ ................................ ................................ .....................  3 
4.4.3  Straightness  ................................ ................................ ................................ ................................ ...........  3 
4.4.4  Ovality  ................................ ................................ ................................ ................................ .....................  3 
4.5 Scarfing  ................................ ................................ ................................ ................................ ..................  3 
4.6 Freedom from defects  ................................ ................................ ............... Error! Bookmark not defined.  
4.7 Cross -welds  ................................ ................................ ................................ ................................ ...........  4 
4.8 Coating  ................................ ................................ ................................ ................................ ...................  4 
5 Packing and marking  ................................ ................................ ................................ ............................  4 
5.1 Packing  ................................ ................................ ................................ ................................ ...................  4 
5.2 Marking  ................................ ................................ ................................ ................................ ...................  4 
6 Inspection and methods of test  ................................ ................................ ................................ ...........  5 
6.1 Inspection  ................................ ................................ ................................ ................................ ...............  5 
6.2 Tensile test  ................................ ................................ ................................ ................................ .............  5 
6.3 Ovality test  ................................ ................................ ................................ ................................ .............  5 
6.3.1  Apparatus  ................................ ................................ ................................ ................................ ...............  5 
6.3.2  Test pieces  ................................ ................................ ................................ ................................ .............  5 
6.3.3  Procedure  ................................ ................................ ................................ ................................ ...............  5 
6.4 Visual test for scarfing  ................................ ................................ ................................ ..........................  6 
6.4.1  Apparatus  ................................ ................................ ................................ ................................ ...............  6 
6.4.2  Test pieces  ................................ ................................ ................................ ................................ .............  6 
6.4.3  Procedure  ................................ ................................ ................................ ................................ ...............  6 
6.5 Visual test for chatter  ................................ ................................ ................................ ............................  7 
6.5.1  Apparatus  ................................ ................................ ................................ ................................ ...............  7 
6.5.2  Test pieces  ................................ ................................ ................................ ................................ .............  7 
6.5.3  Procedure  ................................ ................................ ................................ ................................ ...............  7 
6.6 Flattening test  ................................ ................................ ................................ ................................ ........  7 
6.6.1  Apparatus  ................................ ................................ ................................ ................................ ...............  7 
6.6.2  Test pieces  ................................ ................................ ................................ ................................ .............  7 
6.6.3  Proce dure  ................................ ................................ ................................ ................................ ...............  7 
6.7 Flare test  ................................ ................................ ................................ ................................ .................  9 
6.7.1  Apparatus  ................................ ................................ ................................ ................................ ...............  9 
6.7.2  Test piece  ................................ ................................ ................................ ................................ ...............  9 
6.7.3  Procedure  ................................ ................................ ................................ ................................ ...............  9 
Annex  A (informative)  Sampling and compliance  ................................ ................................ .......................  11 
A.1 Sampling  ................................ ................................ ................................ ................................ ..............  11 DRS 263 -3: 2020  
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 A.2 Compliance  ................................ ................................ ................................  Error! Bookmark not defined.  
 DRS 263 -3: 2020  
v                ©RSB 2020 - All rights reserve d 
 Foreword   
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Techn ical committ ees are ratified  by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS  263-3 was prepared by Technical Committee RSB/TC 47, Steel aluminium and related products . 
In the preparation of this standard, refere nce was made to the following standard:  
1) SANS 657 -3 Steel tubes for non -pressure purposes — Specification — Part 3 : Steel tubes for rolls for 
conveyor belt idles  
The assistance de rived from the above source is hereby acknowledged with thanks.  
This second  edition cancels and replaces the first  edition (RS  263-3: 2015 ) which has been technically 
revised.  
RS 263 consists of the following parts, under the general title Steel tubes for non -pressure purposes — 
Specification:  
 Part 1: Sections for scaffolding gener al engineering and structural applications   
 Part 2: Steel tubes for cycles  
 Part 3: Steel tu bes for rolls for conveyor belt idles  
 Part 4: Steel tubes for rolls for round, oval, square and rectangular section for furniture . 
Committee membership  
The followi ng organizations were represented on the Technical Committee on  Steel aluminium and related 
products  (RSB/TC 47) in the preparation of this standard.  
MANUMETAL  
Rwanda Transport Development Agency (RTDA)  
HEROCEAN Ltd  DRS 263 -3: 2020  
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 AFRIFOAM  
IPRC Ngoma  
Mota Engil  
Ministry of infrastructure (MININFRA)  
National quality testing laboratory (NQTLD)  
Rwanda  Standards Board  (RSB) – Secretariat  DRS 263 -3: 2020  
1                ©RSB 2020 - All rights reserve d 
 Steel tubes for non -pressure purposes — Specification — Part 3: Steel 
tubes for rolls for conveyor belt idles  
1 Scope   
This Draft Rwanda Standard covers the requirements , sampling and test methods  of welded steel tubes for 
use in the manufacture of rolls for conveyor belt idlers.  
2 Normative references   
The following documents are referred to in the text in such a way that some or all of  their c ontent constitutes 
requirements 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.  
RS ISO 6892 -1, Metallic materials – Tensile te sting – Part 1: Method of test at room temperature  
3 Terms and definitions   
For the purposes of this standard , the follow ing terms and definitions apply  
3.1  
acceptable  
acceptable to the authority administering this standard, or to the parties concluding th e purchase contract, as 
relevant  
3.2  
defective  
steel tube that fails in one or more respects to comply with the relevant requirements of this standard  
3.3  
lot  
not less than 25 and not more than 3 200 tubes of the same nominal outside diameter, nominal wall thickness 
and length, made by one manufacturer, and submitted at any one time for inspection and testing.  
4 Requirements  
4.1 Grade and type  
4.1.1  Type  
Tubes for rolls shall be of electrically (induction/resistance) welded mild steel.   
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 4.1.2  Grade  
The grade of the tube s hall comply with the properties given in table 1.  
Table 1 —Tensile properties of tubes  
Yield stress  
MPA, min  Tensile strength  
 MPa, min  Elongation  
%, min  
230 320 10 
 
4.2 Material  
Tubes shall be of steel whose ladle chemical composition complies with the foll owing:  
a) carbon content: 0.25 %, max, (by mass); and  
b) sulfur and phosphorus content: each 0.06 %, max, (by mass).  
4.3 Mechanical properties  
4.3.1  The tensile strength, yield stress and elongation of a tube shall be determined in accordance with 6.3, 
and shall b e at least the appropriate values given in table 1.  
4.3.2  When tested in accordance with 6.7 and 6.8 a tube shall show no sign of cracking.  
4.4 Dimensions  
4.4.1  Outside diameter and wall thickness  
4.4.1.1  The nominal outside diameter , actual outside diameter and  of a tube shall be one of the values 
given in Table 2.  
4.4.1.2  The wall thickness shall be at least equal to the appropriate nominal value given in Table 2.  
Table 4 — Dimensions of tubes  
S/N Nominal outside 
diameter  Outside diameter  Ovality 
Max.  Nominal 
preferred 
wall 
thickness  Nominal 
alternative 
wall 
thickness  Max.  Min  
1 101 101.8  101 0.4 3 3.5 
2    108 108.2  108 0.4 3.8 4.5 
3    127 127.2  127 0.4 3.8 4.5 or 6  
4  133 133.3  133 0.4 4 6 DRS 263 -3: 2020  
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 5   152 152.6  152 0.4 4 6 
6    159 159.1  159 0.5 4 6 
7   165 165.3  165 0.5 4.5 6 
8  178 178.1  178 0.6 4.5 6 
9    219 219.4  219 0.6 6 6 
 
4.4.2  Length  
Except when tubes of specified “mill cut” length are specified by the purchaser, tubes shall be supplied in 
random lengths of 5.5 m - 8 m. 
4.4.3  Straightness  
In any lengt h of tube, any deviation from straightness shall not exceed 1 in 1 000, measured at the midpoint of 
the tube.  
4.4.4  Ovality  
4.4.4.1  Ovality of a tube ( A) is given by:  
𝐴=𝑎−𝑏 
where ;  
a is the greater diameter; and  
b is the lesser diameter.  
4.4.4.2  The maximum  ovality is specified in Table 2.  
4.5 Scarfing  
4.5.1  The inner and outer weld protrusion shall be removed by scarfing.  
4.5.2  The outer scarfing shall blend smoothly with the outer diameter of the tube and shall not protrude 
above the tube by more than 0.1 mm o r indent within the wall of the tube by more than 0.1 mm.   
4.5.3  The inner scarfing shall not stand protrude of the tube wall by more than 0.1 mm or indent within the 
wall of the tube by more than 0.35 mm.  
4.5.4  When tested in accordance with 6.5, the de pth or height of the scarfed section over an area of 15 
mm either side of the centre line of the scarfed section shall not exceed 0.1 mm.   
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 4.5.5  The longitudinal variation of the scarfing shall not exceed the values indicated in Table 3.  
Table 3 — Longitud inal weld variation  (Dimensions in millimetres ) 
S/N Outside diameter (OD) of tube  Tolerance  
1  OD ˂ 127  ± 0.15  
2  127 ≤ OD ≤ 152.4  ± 0.175  
3  OD ˃ 152.4  ± 0.2  
4.5.6  When tested in accordance with 6.6, the protrusion or indent of chatter shall not exceed 0.1 mm.  
4.6 Workmanship  
4.6.1  Tubes shall have an acceptable finish and shall be free from defects  that affect their serviceability.  
4.6.2  The presence of superficial “powder” rusting on the surface of uncoated tubes shall not be regarded 
as prejudicial to the serviceability of the tubes.  
4.6.3  Tubes shall be supplied with “mill cut” ends and any def ormation shall not extend more than 100 mm 
from the cut.  
4.7 Cross -welds  
Tubes for rolls shall have no cross -welds  
4.8 Coating  
Unless otherwise specified by the purchaser tubes shall be supplied uncoated.  
5 Packing and marking  
5.1 Packing  
Tubes shall be supplied loose  or bundled as required. When supplied in bundles, only tubes of the same 
nominal outside diameter and wall thickness shall be packed together.  
5.2 Marking  
5.2.1  The following information shall appear in legible and indelible marking on a label or labels atta ched to 
at least one bundle, carton or pallet, as relevant, per siz e of the tube in a consignment. The following 
information shall be legibly and indelibly marked on each tube in one of the official languages used in 
Rwanda:  
a) manufacturer’s name or trade m ark; and  
b) batch code (if required).  DRS 263 -3: 2020  
5                ©RSB 2020 - All rights reserve d 
 5.2.2  The following information in one of official languages used in Rwanda shall appear in legible and 
indelible marking on a label securely attached to each bundle:  
a) manufacturer’s name or trade mark;  
b) batch code or o rder number;  
c) grade and type; and  
d) nominal outside diameter and wall thickness.  
6 Inspection and methods of test  
6.1 Inspection  
Visually examine and measure each tube in the sample for compliance with the requirements of 4.4 - 4.8. If 
required, sampling shall be  done in accordance with annex A.   
6.2 Tensile test  
Carry out the test in accordance with the relevant test method given in RS ISO 6892 -1 and check for 
compliance with the requirements of 4.3.1. For the determination of elongation, use a gauge length of 5.65√𝑆𝑜 
(where  So is the original cross -sectional area).  
6.3 Ovality test  
6.3.1  Apparatus  
6.3.1.1 V -rollers.  
6.3.1.2 Dial gauge with probe.  
6.3.2  Test pieces  
From the pipe(s) selected for testing, cut a piece of 1 m in length and Deburr the test piece.  
6.3.3  Procedure  
6.3.3 .1 Place a test piece on the v -rollers and position the dial gauge probe in such a way that it touches the 
outside of the tube at a point diametrically opposite a support roller (see figure 1).  
6.3.3.2 Rotate the tube about its longitudinal axis (centreli ne) and complete a full revolution of the tube.  
6.3.3.3 Set the zero point of the dial indicator at the lowest point on the tube circumference and then read the 
ovality as the maximum deflection of the dial indicator needle.    
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 6.3.3.4 The ovality shall not  exceed the values given in table 2.  
 
Figure 1 — Test for ovality  
 
6.4 Visual test for scarfing  
6.4.1  Apparatus  
6.4.1.1 V -rollers.  
6.4.1.2 Dial gauge with probe for measuring ovality  
6.4.2  Test pieces  
From the pipe(s) selected for testing; cut a piece of 1 m in leng th and Deburr the test piece.  
6.4.3  Procedure  
6.4.3.1 Place a test piece on the v -rollers and position the dial gauge probe in such a way that it touches the 
outside of the tube initially away from the scarfed section.  
6.4.3.2 Rotate and slide the tube along i ts longitudinal and horizontal axis as appropriate.   
DRS 263 -3: 2020  
7                ©RSB 2020 - All rights reserve d 
 6.4.3.3 Measure the depth or height of the external scarf over the length of the tube covering an area 15 mm 
either side of the scarfed section of the tube.   
6.4.3.4 The depth or height of the scarfed section over this area shall not exceed the values indicated in 4.5.2.  
6.5 Visual test for chatter  
6.5.1  Apparatus  
6.5.1.1 V -rollers.  
6.5.1.2 Dial gauge with probe.  
6.5.2  Test pieces  
From the pipe(s) selected for testing; cut a piece of 1 m in length and Deburr the test piece.  
6.5.3  Procedure  
6.5.3.1 Place a test piece on the v -rollers and position the dial gauge probe as appropriate.  
6.5.3.2 Whilst moving the tube along its longitudinal axis (along the weld seam); measure the height by which 
the scarfing protrudes abov e the outer diameter of the tube and the depth of indentation which the scarfing 
presents beneath the diameter of the tube outer wall.   
6.5.3.3 The readings obtained shall not exceed the values indicated in 4.5.4.  
6.6 Flattening test ( iso standards)  
6.6.1  Apparatu s  
Compressive testing machine with parallel platens of width at least equal to 1.5 times the diameter of the pipe 
under test.  
6.6.2  Test pieces  
From the pipe selected for testing; cut two pieces of pipe (at least 40 mm each in length) and Deburr the test 
pieces.  
6.6.3  Procedure  
6.6.3.1 Place one test piece in the testing machine with the weld positioned as shown in figure 2(a).  
6.6.3.2 Apply a steadily increasing force until the distance between the two platens is 60 % ± 1 % of the actual 
outside diameter of the pipe (see figure 2(b)).   
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 6.6.3.3 Remove the test piece and examine it for signs of cracking. Check for compliance with 4.3.2.  
 
6.6.3.4 Place one test piece in the testing machine with the weld positioned as shown in figure 2(c).  
6.6.3.5 Apply a steadily i ncreasing force until the distance between the two platens is 15 % ± 1 % of the actual 
outside diameter of the pipe (see figure 2(d)).  
6.6.3.6 Remove the test piece and examine it for signs of cracking. Check for compliance with 4.3.2.  
 
 
 
 
 
DRS 263 -3: 2020  
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 Figure 2 — Flattening test  
 
 
6.7 Flare test  
6.7.1  Apparatus  
6.7.1.1 Compressive testing machine;   
6.7.1.2 Steel cone of included angle 60° and of base diameter at least 1.1 times the outside diameter of the 
pipe 
6.7.2  Test piece  
Cut a piece of suitable length but of length equal  to at least the outside diameter of the pipe and Deburr the 
ends of the test piece.  
6.7.3  Procedure  
6.7.3.1 Place the cone and the test piece in the testing machine as shown in figure 3.  
6.7.3.2 Apply a steadily increasing force until the end of the test pie ce flares to a diameter 10 % ± 1 % larger 
than the outside diameter of the pipe.  
6.7.3.3 Examine the flared end of the test piece and check for compliance with 4.3.2.  
 
 
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 Figure 3 ― Flare test  
 
 DRS 263 -3: 2020  
11                ©RSB 2020 - All rights reserve d 
 Annex  A 
(informative)  
 
Sampling and compliance  
A.1 Sampling  
A.1.1  The fol lowing sampling procedure shall be applied in determining whether a lot complies with the 
relevant requirements of this part of the standard.   
Table A.1 ― Sampling  
Lot size. number of tubes  Sample size. number of 
tubes  Number of defectives allowed  
Inspection  Testing  
25 – 90  13 0 0 
91 - 150  20 1 1 
151 - 280  32 2 1 
281 - 500  50 3 1 
501 – 1 200  80 4 2 
1 201 – 3 200  125 5 2 
 
 DRS 263 -3: 2020  
 
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