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Compression Packing

Pre-formed braided or molded rings of sealing material that are stacked in a stuffing box (packing gland) around a rotating or reciprocating shaft to prevent leakage of the process fluid. The rings are compressed by a packing gland follower, which forces the packing material against the shaft and stuffing box bore to create a seal. Materials: graphite-impregnated (for high temperature -200 to +650°C in non-oxidizing media, excellent sealing and low friction), PTFE/Teflon (universal chemical resistance, -200 to +260°C, low friction), aramid/Kevlar (high pressure, abrasive fluids, pumps, valves), carbon fiber (high speed and temperature), PTFE/graphite combination (versatile, moderate temperature/pressure), and flax/cotton (economical, water service only). Cross-section sizes: 3×3 mm to 50×50 mm (square). Per API 622 (valve packing), ASME and EN standards. Packing requires controlled leakage (2-60 drops/min for pumps) to lubricate the shaft — zero-leakage overtightening causes shaft scoring and premature packing failure. Replacement: remove old packing, inspect shaft sleeve for wear, install rings with staggered joints, and adjust gland to achieve target leakage rate. Brands: John Crane, Chesterton, Garlock, Palmetto.

What you need to know

  • Pre-formed braided or molded rings of sealing material that are stacked in a stuffing box (packing gland) around a rotating or reciprocating shaft to prevent leakage of the process fluid.
  • The rings are compressed by a packing gland follower, which forces the packing material against the shaft and stuffing box bore to create a seal.
  • Materials: graphite-impregnated (for high temperature -200 to +650°C in non-oxidizing media, excellent sealing and low friction), PTFE/Teflon (universal chemical resistance, -200 to +260°C, low friction), aramid/Kevlar (high pressure, abrasive fluids, pumps, valves), carbon fiber (high speed and temperature), PTFE/graphite combination (versatile, moderate temperature/pressure), and flax/cotton (economical, water service only).
  • Cross-section sizes: 3×3 mm to 50×50 mm (square).
  • Per API 622 (valve packing), ASME and EN standards.

Full definition

Compression packing is a critical component in sealing applications, particularly in the context of rotating or reciprocating shafts within various industrial equipment. These pre-formed braided or molded rings of sealing material are strategically placed in a stuffing box, also known as a packing gland, to create an effective barrier against process fluid leakage. The packing material is compressed by a follower, which applies pressure to ensure a tight fit against the shaft and the bore of the stuffing box, thus forming a reliable seal. The effectiveness of compression packing is influenced by the material composition, design, and installation practices, making it essential for engineers and maintenance personnel to understand these factors to prevent leaks and maintain equipment performance.

The materials used for compression packing vary widely, each offering distinct advantages based on temperature, pressure, and fluid compatibility. For instance, graphite-impregnated packing is ideal for high-temperature applications, functioning effectively between -200°C to +650°C in non-oxidizing media, while PTFE (Teflon) packing exhibits universal chemical resistance and operates efficiently from -200°C to +260°C, making it suitable for a variety of fluids. Aramid (Kevlar) packing is designed for high-pressure applications and abrasive fluids, often found in pumps and valves, while carbon fiber packing excels in high-speed and high-temperature environments. A PTFE/graphite combination offers versatility for moderate temperature and pressure conditions, whereas flax and cotton packing serves as a cost-effective solution for water service only.

When it comes to installation, proper technique is crucial. The cross-section sizes of compression packing can range from 3×3 mm to 50×50 mm (square), and adherence to standards such as API 622 for valve packing, ASME, and EN standards is essential. It is important to maintain controlled leakage rates, typically between 2 to 60 drops per minute for pumps, to ensure adequate lubrication of the shaft and prevent damage. Over-tightening the packing can lead to shaft scoring and premature failure, negating the benefits of the seal. Regular inspection and replacement of packing materials, along with careful installation practices such as staggering joints, are vital for maintaining the integrity of the seal and the overall efficiency of the equipment.

What you need to know

  • What you need to know: Compression packing is designed to prevent fluid leakage in rotating or reciprocating shafts.
  • The materials used include graphite-impregnated, PTFE, aramid, carbon fiber, and flax/cotton, each suited for specific applications.
  • Cross-section sizes of compression packing range from 3×3 mm to 50×50 mm (square), allowing for versatility in various equipment.
  • Controlled leakage rates are crucial, with acceptable limits between 2 to 60 drops per minute to ensure lubrication and prevent damage.
  • Proper installation and maintenance practices are essential to prolong the life of the packing and prevent shaft scoring.

Industrial applications

  • 1Used in pumps to seal process fluids while allowing for controlled leakage for lubrication.
  • 2Applied in valves to prevent leakage of fluids in various industrial processes.
  • 3Utilized in rotating equipment such as mixers and agitators to maintain fluid containment.
  • 4Employed in compressors to seal the interface between moving and stationary components.
  • 5Implemented in hydraulic systems to prevent fluid loss and maintain system pressure.

Common mistakes

  • ✕Over-tightening the packing, which can lead to shaft damage and premature failure.
  • ✕Failing to stagger joint placements during installation, which compromises the seal integrity.
  • ✕Neglecting to inspect the shaft sleeve for wear before replacing packing, leading to recurring leaks.
  • ✕Using the wrong material for specific applications, resulting in inadequate sealing performance.
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Pro tip

Always inspect and clean the shaft surface before installing new packing to ensure a proper seal and extend the life of the packing material.

Technical standards

  • API 622 - Standard for Packing for Valves, focusing on leakage control.
  • ASME - American Society of Mechanical Engineers standards applicable to sealing systems.
  • EN - European Norms for sealing materials and packing applications.

Suppliers of seals & gaskets in Mexico

AguascalientesVer Hule Industrial
Ciudad JuárezVer Hule Industrial
Ciudad de MéxicoVer Hule Industrial
GuadalajaraVer Hule Industrial
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