What is the difference between Mechanical Seal and Gland Packing?

Seal and packing are integral and essential elements in a pump system, shaft, and several other mechanical engineering applications. Mechanical seals and gland packing are the top-rated and most-preferred sealing mechanisms. There are differences between features and work mechanism, though. Hence, the selection has to be made with care. Incorrect selection may lead to higher maintenance costs and lower operational efficiency. The article gives a quick comparison between the two.

Gland packing is a conventional shaft seal which is preferred by mechanical engineers. In certain applications, gland packing is preferred over mechanical seals, e.g., dealing with aggressive fluids. If there is any leakage, then it can be adjusted while the pump is in service. In the other scenario (when mechanical seal is used), it is not possible. The gland packing is not suitable for every situation. For example, it is not an ideal solution for applications where abrasive liquids are used. In Gland Packing, rope-like braided material is packed around the shaft. Thus, the gap between the pump and shaft gets filled with the packing material. The packing also requires frequent adjustment and lubrication.

Leakage increases with use because the packing wears away gradually which needs to be repacked. Also, the groove needs replacement time and again. To keep the gland packing cool; a constant flow of water is required. As the packing material generates friction against the shaft, more drive power is needed to turn the shaft. It causes wastage of energy. Both gland packing and mechanical seals are effective and useful. It depends on economic viability, personal preference and requirement specification.