Liner bags for IBC containers, drums and bulk bags are essential packaging components across South Africa's chemical, agricultural, food ingredient, pharmaceutical and mining sectors. Getting the specification right directly affects product protection, filling and discharge efficiency, and compliance with transport and storage regulations. This guide covers everything industrial buyers in South Africa need to know.
What is a liner bag?
A liner bag is a flexible inner container — typically made from polyethylene film — designed to sit inside a rigid or semi-rigid outer container (an IBC, drum, pail, or bulk bag). The liner provides the primary containment and product-contact surface, while the outer container provides structural support.
Liner bags serve several critical functions:
- Product protection — preventing contamination from the container wall (which may carry residues from previous products)
- Container protection — preventing corrosive or reactive products from damaging the outer container
- Efficient discharge — smooth film surface facilitates complete product emptying with less waste
- Hygiene — single-use liners eliminate the risk of cross-contamination between product batches
IBC liner bags — types and specifications
Intermediate Bulk Container (IBC) liners are the most common type of liner bag in South African industrial use. Standard IBCs have a 1,000 litre capacity and come in two primary configurations:
Cage IBC (most common in SA): A rigid plastic blow-moulded inner bottle within a galvanised steel cage on a pallet. Liner bags for cage IBCs typically fit either:
- Inside the bottle — for products where the bottle can be reused and the liner provides the clean product contact surface
- Over the cage — for products that require filling directly into the flexible liner without the bottle
Stainless steel IBC: Used in pharmaceutical, food and high-value chemical applications. Liners for stainless IBCs must meet food-grade or GMP requirements.
IBC liner bag specifications
When specifying an IBC liner bag, the key parameters are:
Material grade:
- LDPE food-grade — for food ingredients, flavourants, pharmaceutical excipients
- LDPE industrial grade — for non-food chemicals, detergents, lubricants
- LLDPE — for heavier, more abrasive products requiring improved puncture resistance
- HDPE — for corrosive chemicals requiring a stiffer, more chemical-resistant film
- Anti-static (FIBC Type C or D) — mandatory for flammable, combustible dusts and powders in Zone 20/21/22 areas
Film thickness:
- Light duty: 80–100 micron (suitable for free-flowing liquids and light powders)
- Standard duty: 120–150 micron (most common specification for general industrial use)
- Heavy duty: 180–250 micron (viscous liquids, abrasive products, products with sharp particles)
Fitments:
- Plain open top — filled from the top, sealed by tying or heat-sealing
- Spout top — for controlled filling from filling equipment
- Bottom discharge spout — fitted through the IBC's base valve, allowing gravity or pump discharge without removing the liner
- Top fill / bottom discharge combo — maximum efficiency for filling and emptying cycles
Common specification error: Under-specifying film thickness for viscous or heavy products. A 100-micron liner that leaks under the weight of a full 1,000L fill of a dense liquid creates a costly and potentially hazardous situation. When in doubt, go heavier.
Drum liner bags
Drum liners are flexible bags designed to fit inside standard steel or plastic drums (210 litre, 120 litre, 60 litre or 25 litre). They follow the same material and specification logic as IBC liners but at smaller scale.
Key drum liner specifications:
- Round-bottom vs. flat-bottom — round-bottom liners conform better to drum geometry; flat-bottom liners are simpler to manufacture and lower cost
- Heat-sealed vs. welded seams — welded seams provide higher strength for heavy products
- Tie handles — allow the liner to be secured to the drum rim before filling
For drums used in food ingredient, pharmaceutical or high-purity chemical applications, specify food-grade LDPE produced in a HACCP-controlled facility with batch documentation. Flexweb's liner bags are produced in our BRC and HACCP-certified Germiston facility with full batch traceability.
Chemical compatibility — critical for selection
The most important factor in liner bag selection is chemical compatibility between the product and the liner material. Polyethylene is broadly chemically resistant but has limitations:
Compatible with most standard PE grades:
- Water-based products (cleaners, coatings, food ingredients)
- Alcohols and glycols
- Dilute acids and alkalis
- Food-grade oils and fats
- Agricultural chemicals (check specific product SDS)
Requires specialist material selection:
- Concentrated acids (HCl, H₂SO₄, HNO₃) — may require HDPE or HDPE/liner combination
- Solvents (ketones, esters, aromatics) — PE not compatible; specialist materials required
- Oxidising agents — consult with your liner supplier before specifying
Always check the product Safety Data Sheet (SDS) Section 7 (Handling and Storage) for packaging compatibility guidance. Flexweb's technical team can assist with compatibility assessment for your specific product.
UN-rated liners for hazardous goods
Products classified as dangerous goods under the ADR/SANS 10228 transport regulations may require UN-rated packaging. UN-rated liners are tested and certified to specific performance standards (drop, stacking, vibration, hydraulic pressure) and carry a UN marking.
If you are transporting products classified as Class 3 (flammable liquids), Class 6 (toxic substances), Class 8 (corrosives) or other dangerous goods, consult with your logistics provider and liner supplier to determine whether UN-rated liners are required for your specific product and transport configuration.
Selecting a liner bag supplier in South Africa
When evaluating liner bag suppliers, the key criteria are:
- Certification — for food ingredient, pharmaceutical and retail-supply applications, require BRC and/or HACCP-certified production
- Batch traceability — the ability to trace any delivered batch back to raw material inputs and production date
- Film quality consistency — liner bags from inconsistent film extrusion show variable thickness, seal quality and dimensional accuracy
- Local manufacture — local supply means shorter lead times and the ability to adjust specifications quickly when product requirements change
- Technical support — a supplier who will advise on compatibility, specification and fitment options rather than just selling standard product
Flexweb manufactures IBC liner bags, drum liners and bulk bag liners from our Germiston facility. Contact our team to discuss your specific requirements and receive a detailed specification and quotation.