Study of Product Quality Control Practices in Polypropylene Woven Sack Manufacturing in Onitsha, Anambra State

Polypropylene woven sacks are the dominant packaging material for agricultural commodities, cement, fertiliser, and chemicals in Nigeria, with a significant concentration of manufacturers operating in Onitsha, Anambra State. Despite their widespread use, systematic documentation of product quality control practices in this sub-sector is lacking. This study examines the quality control systems, inspection methods, and process management practices employed by polypropylene woven sack manufacturers in Onitsha, assessing the relationship between quality control intensity and product defect outcomes. A survey instrument covering quality planning, in-process inspection procedures, finished goods testing protocols, and non-conformance management was administered to production managers across 22 manufacturing facilities. Product samples were independently tested for tensile strength, elongation, seam strength, mass per unit area, and ultraviolet stabilisation adequacy following TAPPI and ISO standard methods. Results show that only 31 percent of manufacturers conducted statistical process control on tape extrusion parameters, while 65 percent relied exclusively on visual end-product inspection. Laboratory tensile testing of finished sacks was practised by 28 percent, predominantly the larger-scale manufacturers. Independently tested samples from 9 of 22 manufacturers failed tensile strength requirements for 50 kg agricultural sack applications. Ultraviolet stabilisation was inadequate in 45 percent of tested samples. The study recommends the adoption of in-process statistical quality control, mandatory finished product testing against national standards, and engagement of the Standards Organisation of Nigeria in market surveillance to protect agricultural commodity packers from substandard sack failures. Keywords: polypropylene woven sack, quality control, Onitsha, Anambra State, tensile strength