TDC3 (6199 )P3 
    First Edition  
 
 
 
 
 
 
 
Textiles – High Density Polyethylene (HDPE)/ Polypropylen e (PP) 
Woven Sacks for packing f ood grains – 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 S acks for 
Packaging food grains.  
 
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 14887 : 2014 Textiles – High Density Polyethylene (HDPE)/ Polypropylene (PP) Woven Sacks 
for Packaging of 50kg Food Grains – Specifications.  
ISO 23560: 2015 Woven Polypropylene Sacks for bulk packaging of foodstuffs.  
 
 
 
  
1 
 1  Scope  
This Draft Tanzania Standard prescribes the requirements of two types of HDPE /PP woven sacks suitable 
for packaging of all types of food grains (wheat, paddy, rice, pulses, millet, etc.).  
2 Normative references  
The following referenced documents are indispensable for the app lication of this Draft Tanzania  Standard.  
For dated references, only the edition cited applies. For undated references, the latest edition of the 
referenced document (including any amendment s) 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.  
viii) IS 1969 : Textiles - Tensile Properties of Fabrics - Determination of Maximum Force and 
Elongation at Maximum Force: Part 1 Strip Method . 
ix) ISO 3451 -1, Plastics -- Determination of ash -- Part 1: General method s. 
3 Terms and definitions  
For the purposes of this Draft Tanzania Standard, the following terms and definitions shall apply.  
3.1 HDPE /PP Sacks  
Cont ainer 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.  
  
2 
 3.4 Ends  
Yarns running along the length of and parallel to the sacking selvedge.  
3.5 Picks  
Yarns running across the width of the fabric and “perpendicular” to the sacking selvedge.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         
3.6 Sacking  
A coarse fabric used for making sacks or bags . 
3.7 Bale  
 
A rectangular pressed rigid package containing woven bags cov ered with protective wrappings that are 
stitched and/or securely bound.  
3.8 Contract – mass (bale)  
 
The mass as obtained by multiplying the nominal mass of a bag by specified number of bags in that bale.  
3.9 Lot 
 
All bale containing similar woven bags.  
4   Manufacture  
4.1 Raw material  
The HDPE or PP used for manufacture of tape shall be of the acceptable quality. The  raw material 
composition to be used for manufacturing of the HDPE/PP woven sacks shall be as agreed to between the 
buyer and seller.  
4.2 Fabric  – The fabric used in the manufactur ing of HDPE /PP woven bags shall be woven on a circular 
loom  from HDPE/PP tapes having not more than 3mm  (tolerance of ± 10%) and linear density (600 denier).  
The denier of HDPE /PP tape used in the manufacturing  of woven fabric/sacks shall be subjected to the 
following tolerances:  
 a) ± 10% on individual value, and  
 b) ± 5 % on average.  
The construction particulars specified are expected to ensure aeration of food grains. The fabric shall be 
woven with anti – slip pa ttern (as given in Fig. 1) to avoid oozing of grains out of the sacks and for better 
stack ability.  
4.3 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. Also  sacks shall be produced from tubular fabric woven on a circular loom and cut to the required 
length.  
  
3 
 Fig 1 – Anti – Slip Weaving Pattern (with 4 shuttle machine)  
1 x x x  x  x x x  x  x x x  x  Nose down  
2  x  x x x  x  x x x  x  x x x Nose down  
3    x  x    x  x    x  x Nose Up  
4 x  x    x  x    x  x    Nose Up  
5 x x x  x  x x x  x  x x x  x  Nose down  
6  x  x x x  x  x x x  x  x x x Nose Up  
7    x  x    x  x    x  x Nose down  
8 x  x    x  x    x  x    Nose down  
9 x x x  x  x x x  x  x x x  x  Nose Up  
10  x  x x x  x  x x x  x  x x x Nose Up  
11    x  x    x  x    x  x Nose down  
12 x  x    x  x    x  x    Nose Up  
13 x x x  x  x x x  x  x x x  x  Nose down  
14  x  x x x  x  x x x  x  x x x Nose down  
15    x  x    x  x    x  x Nose Up  
16 x  x    x  x    x  x    Nose Up  
17 x x x  x  x x x  x  x x x  x  Nose down  
18  x  x x x  x  x x x  x  x x x Nose Up  
19    x  x    x  x    x  x Nose down  
20 x  x    x  x    x  x    Nose down  
21 x x x  x  x x x  x  x x x  x  Nose Up  
22  x  x x x  x  x x x  x  x x x Nose Up  
23    x  x    x  x    x  x Nose down  
24 x  x    x  x    x  x    Nose Up  
Fig 2 – Anti Slip weaving pattern (with 6 shuttle machine)  
1 x x x  x  x x x  x  x x x  x  Nose down  
2  x  x x x  x  x x x  x  x x x Nose down  
3 x  x    x  x    x  x    Nose Up  
4    x  x    x  x    x  x Nose Up  
5 x x x  x  x x x  x  x x x  x  Nose down  
6    x  x    x  x    x  x Nose Up  
7 x x x  x  x x x  x  x x x  x  Nose down  
8  x  x x x  x  x x x  x  x x x Nose down  
9 x  x    x  x    x  x    Nose Up  
10    x  x    x  x    x  x Nose Up  
11 x x x  x  x x x  x  x x x  x  Nose down  
12    x  x    x  x    x  x Nose Up  
13 x x x  x  x x x  x  x x x  x  Nose down  
14  x  x x x  x  x x x  x  x x x Nose down  
15 x  x    x  x    x  x    Nose Up  
16    x  x    x  x    x  x Nose Up  
17 x x x  x  x x x  x  x x x  x  Nose down  
18    x  x    x  x    x  x Nose Up  
19 x x x  x  x x x  x  x x x  x  Nose down  
20  x  x x x  x  x x x  x  x x x Nose down  
21 x  x  x  x  x  x  x  x  x  Nose Up  
22    x  x    x  x    x  x Nose Up  
23 x x x  x  x x x  x  x x x  x  Nose down  
24    x  x    x  x    x  x Nose Up  
X stands for Warp up, blank cells stand for Warp down   
4 
 4.3.1 Bottom Seam  
The stitching of bottom seam shall be done with two rows of chain stitch. The two rows of stitches shall be 
separated from each other by minimum 5mm and the outer stitch shall be minimum 8  mm from the outer 
edge of the sacks. The stitching shall be done with double fold over seam to a  depth of minimum 25  mm, 
so that the stitches pass through a minimum of six layers of the fabric. The number of stitches/dm shall be 
14 ± 2.  
The thread used for stitching shall b e UV stabilized HDPE/PP tape or any other UV thread suitable for the 
purpose. The stitching shall be uniform without any loose thread s or knot s. 
4.3.2 Mouth of the Sack  
The completely open mouth of the sack shall be hemmed with a fold of minimum 5  mm and tapes shall not 
fray. 
4.4 Capacity  
The sack shall have the Maximum capacity of  100 kg. 
5 Requirements  
5.1 Mass of bale  
The mass of bale of sacks (excluding pac kaging materials) shall be with in ± 3% of the mass calculated by 
multiplying the number of sacks with  the mass of sack specified in T able 1.  
5.2 The sacks shall conform to  the requirements specified in T able 1.  
Table 1 – Requirement of the woven HDPE/PP woven sacks  
SN Characteristics  
 Requirements  Tolerance  Test 
Methods  
1 Average Breaking strength of fabric, N, min 
(ravelled strip method, (200mm x 50mm)  
a) Width wise  
b) Length wise   
 
 
500 
500  
 
- 
-  
 
 
ISO 13934: 1  
2 Minimum brea king strength of bottom 
seam (ra velled strip method), Min, N (kgf)  
250  
-  
IS 9030  
3 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 Elongation at break of fabric (%)  
i) Lengthwise, (min)  
ii) Width wise,  (min)   
20 
20  
-  
IS 1969  (Part 
1)  
5 
 NOTE 1: R equirement no. 3 and 7  are is subjected to the agreement between manufacturer and buyer.  
NOTE 2: Depending on the type of grain and weight to be packed, the dimensions will be agreed between manufacturer 
and buyer. Some dimensions are available with manufacturers.  
6 Printing Marking and Pa ckaging . 
6.1 Printing on Sacks  
The sacks shall be printed with food grade printing inks with identification mark of sack manufacture along 
with the information as required by the buyer.  
6.2 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 in formation required by the buyer;  
g) Identification Mark;  
h) Number of sack.  
Note - Each sack shall be compulsorily marked with visible recycling logo as given below at a space on bottom of 
the bag compactible with the art work of the buyer for printing the sack and the bale.  
 
6.3 Pa ckaging  
The sacks shall be packed to form a bale using a layer of HDPE/PP woven fabric and suitably secured. 
The bale shall contain 500 sacks or multiple thereof.  
5 Mass per unit area of the fabric (g/m2), 
min  65  TZS 21  
6 Number of yarns per Decimetre  
i) Ends/dm  
ii) Picks/dm   
40 
40  
± 2%  
± 2%   
TZS 20  
 
7 Ash content (for UV stabilized fabrics), 
Max, Percent   
2.2 - ISO 3451 - 1: 
2008, 
Method A.   
6 
 7 Sampling and Criteria for Conformity.  
7.1 In and consignment, all the sacks of the same construction shall be grouped together to constitute a 
lot. 
7.2 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.  
7.3 The number of samples to be selected depend on the size of the lot and the number of bales to be 
sampl ed shall be in accordance with col umn 2 and col umn 3 of Table 2.  
The number of sacks to be selected from the bales sampled sh all be in accordance with 4 of T able 2 for  
visual inspection, dimensions, ends, picks and mass requirements and shall be in accordance with column 
5 of T able 2 for breaking strength of bottom seam and percent elongation at break requirements.  
 The samples should be selected in accordance with col umn 6 of T able 2 for determination of ash content 
and also breaking of fabric after UV radiation exposure . 
Table 2  - Sample size and criteria for conformity  
No. of HDPE/PP 
sacks in a lot  Number of 
Bales to be 
sampled  Sample size for visual 
Inspection, 
Dimensions, Ends, 
Picks and Mass 
Requirements  Sample size for Breaking 
Strength of HDPE/PP Fabric 
before Exposing to UV 
Radiation, Breaking 
Strength of seam and 
Elongation at Breaking 
Requirements.  Sample Size for 
Breaking Strength  of 
HDPE/PP Fabric after 
Exposing to UV 
Radiation 
Requirement and Ash 
Content.  
Up to 25, 000  3 12 8 1 
25,001 to 50,000  5 20 10 2 
50,001 to 100,000  8 32 13 3 
100,001 and above  12 48 18 4 
 
7.4 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.  
7.4.1 The number of sacks to be selected for testing breaking strength and seam breaking strength shall 
be two per bale selected according to col umn 2 of Table 2 subject to a maximum of 10 bags.  
 
 
 
  
7 
 7.5 Criteria for conformity  
The lot shall be considered as conforming to the requirements of the standard, if the following conditions 
are satisfied:  
a) The number of defective sacks in case of visual inspections, ends, picks and dimensions is up to 
10 percent of the sample size subject to rounding off the fraction to next higher integer.  
b) Note of the sack or bale of 500 sacks weighs after allowing tolerance of ±6 % on individual sack 
and ± 3% on a bale of 500 sacks, higher weight can be accepted.  
c) The average breaking strength of fabric in both lengthwise and width wise is not less than the value 
specified and none of the individual bag value is more than 10 % below the specified value. The 
samples selected for breaking strength tests shall be free from defects in visual inspection, 
dimensions, ends, picks and mass requirements.  
d) The average breaking strength of fabric at bottom seam is not less than the value specified and 
none of the individua l bag value is more than 10 % below the specified value. The samples selected 
for bottom seam breaking strength tests shall be free from defects in visual inspection, dimensions, 
ends, picks and mass requirements and test carried on the centre portion.  
e) None  of the HDPE/PP sack samples after exposing to UV – radiation and weathering shall have a 
breaking strength less than 50 % of the original value.  
f) None  of the sample sacks shall have percentage elongation and ash content outside the specified 
range.  
 
 
 
 
 
 
 
 
 
 
 
 
  
8 
  
 
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. 
Irradian ce level throughout the test shall be maintained at 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 conde nsation exposure and the tempera ture of 
the UV exposure and condensation 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 original 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. Cond ensation 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.