Asia Pacific Fibers

PTA Powder - Bulk Bag Filling Systems

Big Bag Filling Icon


Asia Pacific Fibres PTA (APF), is a global polyester player and a leading manufacturer of PTA (purified terephthalic acid). Over the past 30 years, APF has evolved into Indonesia’s most progressive, flexible and fully integrated polyester producer ranking amongst one of the best in the world.

Reducing workplace risks and ensuring a and safe working environment has always been a priority for APF and they are accredited with ISO 45001-2018 certification by SGS. PTA (Purified Terephthalic Acid) is produced at the Karawang facility, it is the raw material for the production of polyester chips, staple fibers and filament yarns and bottle grade applications.

You can find out more about APF here:




To achieve a high-speed packing line of PTA (white crystalate powder) into bulk bags weighing 1100kg.

PTA-Bridge, Block – or flush ?

PTA  has very unpredictable flow characteristics - making this powder challenging to weigh accurately and fill into jumbo bags.

Owing to the angular shape of PTA crystals they have a tendency to interlock - resulting in a powder which settles ‘solid’ , but flows like water and ‘flushes’ uncontrollably when moving. PTA bridges, then ‘rat holes‘ when discharging from rectangular or circular hoppers or silos of a conventional design.


Webster Griffin engineered and supplied a complete solution with two hi-speed in-line FIBC Bag filling lines.

  • To overcome PTA's unpredictable flow characteristics Webster Griffin designed an anti bridging settling hopper with multiply side angles and large ratio cross-sectional area at discharge point. The design of the hopper ensures controlled powder discharge -essential for accurate high-speed bag filling.
  • The hopper combined with the special design of archimedean evacuation screws allows deaeration of the powder, while preventing rat holes.
  • Pressure balance control - for clean accurate packing of dusty, hazardous powders
  • Each filling line is a self-contained module – including Big Bag, FIBC (Flexible Intermediate Bulk Containers) weigh-fill machine, anti-bridging hopper, powder dosing device, empty pallet magazine/de-stacker, full bag outfeed & accumulating conveyors, Full IS/ATEX  control system.
  • Safety is paramount – PTA flows within a controlled nitrogen environment.
  • All machinery within hazardous Zone Ex II D &  IS intrinsically safe EX ( ATEX ) certified.
Video not specified. Please select one to display.


Webster Griffin successfully designed and installed two high-speed bagging lines for accurate, safe packing of PTA powder into 1.1 ton FIBC’s, Bulk Bags & Jumbo Bags. The total system providing the following benefits:


  • Two hi-speed bulk bag filling lines means that Asia Pacific Fibers can always keep bagging even when carrying out maintenance on one machine.
  • Patented ‘semi-suspension’ filling technique – provides stable full bag and avoids the need for any hydraulic circuits, valves and pumps.
  • Combined throughput of the Big Bag Fillers enables the APF to achieve production targets and clients orders.
  • Clean safe operator environment is provided because during the filling process the bag neck is sealed by the dust-tight inflatable collar while nitrogen in the bag is safely vented back into the circuit by automatically modulated valves.
  • Internal plenum chamber funnels nuisance dust to the dust extraction filter.
  • Consistent weighing accuracy by gross/net weighing system and the automatic 'on spout' top-up which minimised product 'give away'.
  • Precise electronic load cell weighing with data logging and production reporting.

Case Images

Our Experience in Plastics & Resins