TDC3 (6197 )P3 
    First Edition  
 
 
 
 
 
 
Textiles – High Density Polyethylene (HDPE)/ Polypropylene (PP) 
Woven Sacks for packaging of  flour (milled product)  – Specifications.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
 
 
 
 
 
 
 
 
 
  
i 
 Foreword  
 
This First Edition of this D raft Tanzania Standard has been prepared to specify requirements to be complied 
with   manufacturers producing High Density Polyethylene (HDPE )/Polypropylene (PP)  Woven Sacks for 
packing  sugar . 
 
This Draft Tanzania Standard describes the construction of the sacks, their dimensions and test methods 
suitable for ensuring long term storage a nd transportation of foodstuffs.  
In preparation of This Draft Tanzania Standard Assistance was derived from  
IS 12100: 2014 Specification for High Density Polyethylene ( HDPE ) Woven Sacks for packing 
flour.  
ISO 23560: 2015 Woven Polypropylene Sacks for bulk packaging of foodstuffs.  
 
 
 
  
1 
 1Scope  
This Draft Tanzania Standard prescribes the requirements of two types of HDPE /PP woven sacks suitable 
for packing flour.  
 Type 1     Suitable for 25 and 50kg  
 Type 2     Suitable for 5 and 10kg.  
2 Normative references  
The following referenced documents are indispensable for the application of this Draft Tanzanian Standard.  
For dated references, only the edition cited applies. For undated references, the latest edition of the 
referenced document (including any amendment) applies.  
i) TZS 4, rounding off numerical values  
ii) TZS 20, Textiles – Woven fabrics – Determination  of number of threads per unit length and per 
unit width.  
iii) TZS 21, Textiles – Woven or knitted fabrics – Determination of  mass per unit length and per 
unit area.  
iv) TZS 22, Textiles - Woven fabrics - Determination of breaking load and extension  
v) TZS 44, Textiles – Woven or knitted fabrics - determination of width and length.  
vi) TZS 834: 2005,  Textiles – Determination of commercial mass consignments of textiles fibres 
and yarns . 
vii) ISO 13953, Polyethylene (PE) pipes and fittings -- Determination of the tensile strength and 
failure mode of test pieces from a butt -fused joint.  
3 Terms and definitions  
For the purposes of this Draft Tanzania Standard, the following terms and definitions shall apply.  
3.1 HDPE /PP Sacks  
Container made of woven HDPE /PP fabric closed at one end,  
3.2 Liner bag,  
Inner bag which is fitted in a sack to provide additional protective properties against air, water vapour 
migration and effect of light.  
3.3 Laminated sacks  
Sacks made of superimposed  layers of paper, wood or fabric bonded or impregnated with resin and 
compressed under heat.  
3.4 Ends  
Yarns running along the length of and parallel to the sacking selvedge.  
  
2 
 3.5 Picks  
Yarns running across the width of the fabric and “perpendicular” to the sacking selvedge.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
3.6 Sacking  
coarse fabric used for making sacks or bags . 
3.7 Bale  
rectangular pressed rigid package containing woven bags covered with protective wrappings that are 
stitched and/or securely bound.  
3.8 Contr act – mass (bale)  
mass as obtained by multiplying the nominal mass of a bag by specified number of bags in that bale.  
3.9 Lot 
All bale s containing similar woven bags.  
4   Manufacture  
4.1Fabric  – The fabric used in the manufactur ing of HDPE woven bags shall be woven from HDPE /PP 
tapes . The minimum width of tapes used for making fabric shall not be more than 3 mm  and the line ar 
density of the tape shall be minimum of 600 deniers.  
4.2 Sack  
The sack may be produced from fabric woven as a tube and cut to the required length or converted from 
woven fabric produced on a flatbed loom. Such converted material may be laminated prior to conversion 
into sacks.  
4.2.2 Tubular woven fabric  
The sack tube is produced conveniently on a circular loom. The sack tube may also be woven on a flatbed 
loom which effectively weaves two layers of fabric. The weft is passed via the shuttle through each layer in 
turn in such a way that it forms tube in which the weft is continuous around the tube so formed. When this 
method is used, the weft direction tape lies in the transverse direction of the finished sack.  
4.2.3 The construction of fabric found suitable is given in Appendix A.  
4.3 Lamination of the sack  
If so agreed to between the buyer and the seller, the sac k shall be made out of woven fabric laminated with 
low density polyethylene film of uniform thickness not less than 25 microns  (or mass 23g/m2) 
4.3.1  Liner  
Alternatively, the sack may be supplied with loose liner of plastic materials such as LDPE, LLDPE, 
HMHDPE, HDPE  or propylene as required by the buyer. The liner should be at least 10% more in length 
and width of the sack dimensions. In case of LDPE liner, the mass shall not be less than 27  g/m2 and for 
other plastic material, the mass shall not be less t han 24  g/m2.  
4.3.2  The lamination or the loose liner shall be free from pin holes, patches, tears, blisters and any other 
visible defects. The plastics used for lamination or liner shall be made from virgin material.  
4.4 Seam  
If the sack is to be fabricated out of a flat fabric (as distinct from fabrication of a sack from a tubular woven 
fabric), the side and bottom of fabric shall be sewn and in case of tubular woven sack the stitching shall be 
only at the bottom. The stitching shall be done in tw o rows of chain or lock stitches. The two row stitches 
should be separated from each other by about 5mm and the outer row of stitching should be done with fold 
over seam (to a depth of about 25  mm) so that the stitches pass through a minimum of 4 layers of  the fabric. 
The number of stitches per decimetre shall be between 10 and 20.   
3 
 4.4.1  The material used for stitching shall be HDPE tape or any other suitable thread having a minimum 
breaking strength of 50N. it shall have at least 20% higher denier than th at used for making the sack.  The 
stitch shall be uniform and without any loose thread s or knots. 
4.5 Mouth of the Sack  
The mouth of the sack should be selvedge d, hemmed or heat cut, so that the tapes do not f ray. The mouth  
of the sack should be completely  open . 
4.6 Capacity  
The type 1 sack shall have a nominal capacity of 25  kg or 50  kg as ordered and type 2 sacks shall have 
nominal capacity of 5  kg or 10  kg as ordered.  
Note: The capacity of the sack can also base on an agreeme nt between the buyer and seller  but it should not exceed 
the maximum capacity of 100 kg.  
Table 1 – Requirement of the sacks.  
Note 1: Requirement number 8 and number 7 is subjected to the agreement between manufacturer and buyer.  
 
 
 SN characteristics  Requirements  Tolerance  Test 
Methods  50kg  25kg  10kg  5kg 
1. Breaking strength of fabric, N, min  
a) Width wise  
b) Length wise   
500 
500 
  
500 
500 
  
500 
500  
500 
500 
 - TZS 22  
2 Seam Breaking strength, N, min  
i) Side seam  
ii) Bottom seam   
250 
250  
250 
250  
250 
250  
250 
250  
-  
ISO 
13953 - 1 
3 Dimensions(mm), min  
i) length  
ii) width   
900 
540  
630 
480  
550 
400  
450 
300  
-  
TZS 44  
4 Elongation at break of fabric (%)  
i) Lengthwise, (min)  
ii) Width wise, (min)   
20 
20  
20 
20  
20 
20  
20 
20  
-  
TZS 22  
5 Mass per unit area (g/m2), min  65 65 65 65 - TZS 21  
6 Number of yarns per Decimetre  
i) Ends/dm  
ii) Picks/dm   
40 
40  
40 
40  
40 
40  
40 
40  
± 2%  
± 2%   
TZS 20  
7 Ash content (for UV stabilized fabrics), 
Max, Percent  2.2 2.2 2.2 2.2 - ISO 3451 - 
1: 2008, 
Method A.  
8 Average  Breaking strength and 
elongation at break of UV stabilized 
HDPR/PP fabric after been exposed to 
UV radiation and weathering, min (kgf).  Not less than 50%  of original strength  Annex A.   
4 
 5 Marking and Pa ckaging . 
5.1 Marking on Sacks  
The Identification mark of the manufacturer, along with any information required by the buyer, shall be 
printed on the sacks, using ink or another suitable method that will ensure legibility during use.  
5.2 Packaging  
The sacks shall be packed to form a circular bale, using a layer of woven PP fabric for wrapping, and 
suitably secured. Each bale shall contain 500 sacks or a multiple thereof.  
5.3 Marking on bales  
The bales shall be marked with the following information:  
a) The name of the manufacturer;  
b) The type and size of sack;  
c) The gross mass of the bale;  
d) The net mass of the bale;  
e) The month and year of manufacture;  
f) Any other information required by the buyer.  
6 Sampling  and criteria for conformity . 
6.1 In any consignment, all the sacks of the same construction shall be grouped together to constitute a lot.  
6.2 The conformity of the lot to the requirements of this Draft Tanzania Standard shall be determined on 
the basis of the tests carried out on the samples selected from it.  
6.3 Unless otherwise agreed to between the buyer and the seller, the number of bales to be selected at 
random  from a lot shall be according to T able 2.  
Table 2 - Sample size   
  
Number of Bales in the 
Lot Number of Bales to be 
selected  Number of sacks to be 
selected  Permissible 
number of 
defective sacks  
1 1 5 0 
2 2 8 0 
3 to 6  3 12 0 
7 to 20  5 20 1 
21 to 70  8 32 2 
71 and  above  13 52 3 
 
  
5 
 6.4 Number of Tests – The number of sacks to be selected for testing dimensions and mass of sacks shall 
be according to col umn 3 of Table 2.  
6.4.1  The number of sacks to be selected for testing breaking strength and seam brea king strength shall 
be two pe r bale selected according to col umn 2 of Table 2 subject to a maximum of 10 bags.  
6.5 Criteria for conformity  
6.5.1  The lot shall be considered conforming  to the requirements given in Table 1  (parameter number 3 
and 5) , if the number of sacks not meeting the requirements for any one or more of the  characteristics is 
less than or  equal to the corresponding acceptance number  given in column 4 of T able 2.  
6.5.1  The lot shall be considered conforming  to the requirements given in Tab le 1 (parameter number 1) if 
all sacks selected according to 6.4.1 meet the relevant requirements.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
6 
 ANNEX A  
(Normative)  
UV RESISTANCE TEST  
A – 1 To determine the effect of UV radiation and weathering on the breaking strength, the HDPE/PP 
Woven fabrics shall be exposed as given in A - 2 and A – 3. 
A – 2 TEST PROCEDURE  
The test shall be carried out with fluorescent UV – Lamp type B (313 nm or its equivalent).  
The duration of the test shall be 192h (that is eight days) in continuous mode.  
The test cycle shall be: 8h at 60± 3˚C with UV – radiation alternating with 4h at 50 ± 3˚C condensation. 
Irradiance level throughout the test shall be maintained a t 0.63 (+0.04/ -0) W/m2. 
A – 3 TEST PROCEDURE  
A – 3.1 Determine the original average breaking strength of fabric as per test method specified in IS 1969 
(part 1)  
A – 3.2 Expose the specimens alternately to ultraviolet light and condensation in respective test cycle in 
continuous mode for total 192h.  
The type of fluorescent UV lamp, the timing of the UV and condensation exposure and the temperature  of 
the UV exposure and c ondensation shall be specified in A - 2. 
A – 3.3 Determine the average breaking strength of the fabric separately after UV exposure as mentioned 
above.  
A – 3.4 Determine the p ercent retention of original strength as follows:  
Percentage retention of origina l breaking strength = 𝑎
𝑏  𝑥 100 
Where  
a) a= average breaking strength before UV exposure as obtained in A – 3.1 
b) b= average breaking strength after UV exposure as obtained in A – 3.3 
NOTES  
1. The UV source is an array of fluorescent lamps (with lamp emission concentrated in the UV range).  
2. Condensation is produced by exposing the test surface to a heated, saturated mixture of air and water vapour, 
while the reverse side of the test specimen is exposed to the cooling influence of ambient room air.