Section from two diameters
The packing fills the gap between shaft and bore: (65 - 45) / 2 = 10 mm. Packing sold in inch sizes is close to it: 3/8 in is 9.53 mm.
Reference tool — not a repair procedure
Work out the packing before it goes in an RFQ.
Gland packing
Section, rings, length.
Enter the shaft diameter and the bore and depth of the stuffing box. The drawing and the RFQ line update with every change.
Examples:
All 130 engineering tools
Gland packing is ordered by its section, material and length. The stuffing box gives the section: half the difference between the bore and the shaft. Its depth gives the number of rings, and the ring centreline how much packing a set takes. Enter three measurements, and the calculator works them out and writes the RFQ line.
The ring length here is on the centreline, a guide for ordering. Packing makers advise cutting each ring on a mandrel of the shaft diameter, checking it on the shaft and staggering the joints of successive rings at least 90°.
How packing is worked out
Section, rings, length.
Rings from the depth
Depth over section gives the ring count: 50 mm takes five 10 mm rings, four if a 10 mm lantern ring sits in the box.
Length on the centreline
pi × (45 + 10) = 173 mm per ring; five rings take about 0.86 m. Cut each ring on a mandrel and stagger the joints at least 90°.
| Shaft, mm | Section 6 | 8 | 10 | 12 | 14 | 16 |
|---|---|---|---|---|---|---|
| 20 | 82 | 88 | 94 | 101 | 107 | 113 |
| 25 | 97 | 104 | 110 | 116 | 123 | 129 |
| 30 | 113 | 119 | 126 | 132 | 138 | 145 |
| 35 | 129 | 135 | 141 | 148 | 154 | 160 |
| 40 | 145 | 151 | 157 | 163 | 170 | 176 |
| 45 | 160 | 167 | 173 | 179 | 185 | 192 |
| 50 | 176 | 182 | 188 | 195 | 201 | 207 |
| 60 | 207 | 214 | 220 | 226 | 232 | 239 |
| 70 | 239 | 245 | 251 | 258 | 264 | 270 |
| 80 | 270 | 276 | 283 | 289 | 295 | 302 |
| 90 | 302 | 308 | 314 | 320 | 327 | 333 |
| 100 | 333 | 339 | 346 | 352 | 358 | 364 |
Length on the ring centreline, pi × (shaft + section), rounded to the millimetre. A guide for ordering a length, not a cutting dimension: cut the ring on a mandrel and check it on the shaft.
Sources
Section = (bore - shaft) / 2 from the measured shaft, bore and depth per Chesterton’s packing instructions (1830-SSP, GRAPHMAX, 1400R) and the pump and valve packing installation chart ("calculate packing cross section and number of rings needed from recorded measurements"). Cutting on a mandrel of the shaft diameter, butt or skive, with the joints of successive rings staggered at least 90°, per Chesterton, the same chart and the RS PRO packing guide. The centreline length is circle geometry.
Before you send the packing
Questions about gland packing in an RFQ
How is the packing size worked out?
From the stuffing box bore and the shaft or sleeve diameter: section = (bore - shaft) / 2. A 45 mm shaft in a 65 mm bore takes 10 mm packing. Measure the shaft or sleeve where the packing runs.
How many rings does a stuffing box take?
About the depth divided by the section, less a lantern ring where the box has one: 50 mm of depth with 10 mm packing takes five rings, four with a 10 mm lantern ring. Where the pump or valve maker specifies a ring set, use that.
How long is one ring?
On its centreline, pi × (shaft + section): about 173 mm for 10 mm packing on a 45 mm shaft. That is a guide for ordering a length; packing makers advise cutting each ring on a mandrel of the shaft diameter and checking it on the shaft.
Braided packing or die-formed rings?
Braided packing is cut into rings on board from a length; die-formed rings come pressed to the shaft and bore sizes, given as shaft × bore × section. State which you need and the material of the old packing.
What should the request include?
The shaft and bore diameters, the depth, the packing material, the medium, pressure, temperature and shaft speed, and photographs of the old rings and the gland. The service conditions decide the material.
Packing worked out?
Send the line with the photographs.
A calculation is a cross-check on the measurements, not proof. Attach photographs of the old rings and the gland, give the medium, pressure and temperature, and Vessel Core checks them against each other before an offer goes back.
Buyer tools
