Built around the drop, not around the fill weight
A 25 or 50 kilogram sack is thrown, dropped, stacked eight high, driven over bad roads and left in the sun on a dealer’s forecourt. It is handled by people who have no particular reason to be careful with it, several times over, long after it has left your control.
When one bursts, the loss is rarely the material. It is the mess on somebody’s floor, the short delivery, the claim, and a dealer who now tells his customers that your bags split.
Stacked six high and interlocked. The sack has to hold its shape for the pattern to hold.
Heavy duty sacks in 25 and 50 kilogram sizes, made in the material the product and the handling actually require rather than in whichever film the sack line already runs.
The two usual starting points are a heavy co-extruded polyethylene sack and a woven polypropylene sack, and they fail in different ways, so they suit different products. PE is welded shut, which gives a continuous moisture seal and no stitch holes anywhere in the bag. Woven PP has the tear strength that only a woven base gives, and takes a coated or BOPP-laminated outer where the sack has to look like a finished retail product on a shelf. Valve, open mouth, block bottom, side gusset and form-fill-seal formats are all made here.
We build the sack around the drop rather than around the fill weight. A sack of this size is normally proved by a drop test at 1.2 to 1.5 metres, which represents one careful person setting it down. That is not what happens to it in the field. Our heavy grade co-extruded film has been dropped from around 12 metres without bursting, and the reason for building that much margin in is that the handling downstream looks nothing like the handling in the test.
The other half of the work is the closure. A stitched sack has a line of needle holes across its top by design, so a product that has to stay dry is being asked to keep moisture out through a row of punctures. Where that matters we heat seal or ultrasonically seal instead, and the bag has no stitch line at all.
Every one of these can be changed for your application, and a sample is supplied for trial fitment before bulk production.
Questions
The film or fabric is specified against the drop rather than against the fill weight. A 25 or 50 kilogram sack is thrown, stacked, driven over bad roads and left in the sun long after it leaves the plant, and a bag built only to hold the weight fails at the third handling. GI PackTech builds them in heavy co-extruded PE or woven polypropylene, with UV stabilised and temperature-graded options where the storage demands it.
They fail differently, so the product decides. Co-extruded PE is welded shut, giving a continuous moisture seal and no stitch holes anywhere — the right answer for anything that must stay dry. Woven polypropylene gives tear strength a plain film cannot reach and takes coating or BOPP lamination where the sack has to look like a finished retail product. A woven bag with a fitted PE liner combines both where the product needs it.
A valve bag is filled through a small sleeve in one corner that closes itself under the pressure of the product, so the bag never needs a separate sewing or sealing step after filling. It suits high-speed automatic filling of cement, powders, granules and minerals. Valve size is made to your filling spout, usually in the 10 to 18 centimetre range, and block bottom formats are supplied where the sack has to stand square on a pallet.
A sack of this size is normally proved by a drop test at 1.2 to 1.5 metres, which represents one careful person setting it down rather than what happens in the field. GI PackTech’s heavy grade co-extruded film has been dropped from around 12 metres without bursting. The margin exists because downstream handling is nothing like the test, and because a burst sack costs the claim and the customer, not the material.
A PE sack made as a mono-material goes back into the recycling stream as a single polymer, which is what recyclers can actually process — a mixed-material sack usually cannot be separated and is lost. Our heavy duty PE bags are made from linear low-density polyethylene for exactly that reason, and the same construction can be UV stabilised and temperature graded without giving up the single-polymer structure.
GI PackTech manufactures heavy duty 25 kg and 50 kg sacks at Gundlav, Valsad, in Gujarat, as a manufacturer and exporter established in 2006 and certified to ISO 9001:2015. Valve, open mouth, block bottom, side gusset and form-fill-seal formats are made to order in co-extruded PE, woven PP, BOPP laminated woven and lined constructions, with the fill weight, valve and closure built to your filling equipment.
Commonly specified with
Turns a standard shipping container into a sealed bulk vessel
Faster filling without touching the filling machine
Makes the stack behave as one block
Send us the problem
Every product we make is built to order, so the conversation starts with your specification rather than with our price list. Sample liners and trial covers are supplied for fitment before bulk production begins.
