How to Select Compression Packing Seals

Compression packing seals or gland seals are used to seal a variety of fluids under a range of conditions. They are used to help contain water, acids, solvents, gases, oil, and other chemicals that are subjected to various temperatures and pressures.

Compression packing is a common sealing process where a gland along the top ring is tightened, and the packing compressed onto the surface to be sealed. Applications also include packing for valves, pumps, and rotating equipment.

Most compression seals feature a braided, twisted, plaited, or laminated construction. In addition to packing construction, the use of a wet or dry lubricant should be considered when selecting products. Some lubricants are approved for use with food processing applications by the U.S. Food and Drug administration.

Types of Compression Packing Seal Designs

The GlobalSpec SpecSearch Database contains information on various types of compression packing seal designs.

• Braid-over-braid is also called jacket-over-jacket. This design is fabricated by braiding one or more covers over a center core of braided, twisted, or homogeneous materials. Products can be braided round, then calendared square. The weave is soft and dense because of the individual jacket-over-jacket construction, and can carry a high amount of lubricant.
• Braid-over-core designs are produced by round-braiding one or more jackets of yarn, rovings, ribbons, or other forms of materials over a core that may be extruded, twisted, wrapped, or knitted.
• Multi-braid or lattice designs consist of strands that are diagonally-braided for greater strength and longer life. Each strand passes diagonally through the body of the packing at an angle of approximately 45°. This design is resistant to permeation leakage and will not be damaged entirely even if the surface becomes worn.
• Laminated compression packing seals consist of either asbestos and rubber or duck and rubber laminated into slab form and then fabricated into spirals, coils, or rings.
• Plaited packing is constructed from interwoven yarns with pockets formed between each plait to retain lubricant.
• Twisted products have yarns or metallic strands that are twisted around each other to obtain the desired size. One packing size can be used for various size stuffing boxes.