Polytetra buyer guide
PTFE gland packing: sizing & installation
PTFE gland packing seals the stuffing box around a compatible pump shaft or valve stem. For a concentric shaft and bore, the nominal square packing section is half the difference between stuffing-box bore and shaft diameter. Confirm fit, ring count and the equipment manufacturer's installation procedure before ordering.
Measure the stuffing box
Measure shaft or stem diameter, stuffing-box bore and usable depth. For example, a 50 mm bore around a 30 mm shaft gives a nominal 10 mm square section: (50 − 30) ÷ 2. This calculation is a sizing starting point, not approval of the packing for the equipment.
Ring count and cut length
Provide usable box depth and the required ring arrangement. Follow the approved instructions for cut style, joint position, insertion and gland adjustment. Do not assume a universal ring count or tightening torque across pumps and valves.
Pump packing is not valve packing
Rotating shafts introduce frictional heat and may require controlled leakage, flushing or lubrication. Valve stems have different movement and pressure-cycle conditions. Tell the supplier whether the duty is rotary, reciprocating or static.
Choose the complete braid construction
Pure PTFE, soft PTFE, graphite-filled PTFE and aramid combinations have different constructions. Review the medium, concentration, pressure, temperature, speed and shaft surface. The separate packing-selection guide compares application choices across the five catalogue variants.
Confirm suitability before installation
Do not combine maximum temperature, pressure and speed from a data sheet as if they apply simultaneously. Confirm the selected product's operating envelope and follow the equipment-specific commissioning procedure. No emissions certification or zero-leak claim is implied.
Related products & specifications
PTFE Universal Soft Packing
Round and square sections; custom coil lengths
Graphite Filled Teflon Packing
Square sections and formed rings on request
Graphited PTFE & Aramid Combination Packing
Square sections and coil lengths to application