SEAL CONNECTQuick answer: Install packing one ring at a time, seating each ring fully before adding the next, with joints staggered 90° between rings. Set the gland finger-tight only. Then start the equipment with the gland loose enough to leak freely and tighten in small increments over the first hour, stopping at a steady drip. Never adjust the leakage to zero. Most packing failures are caused by over-tightening during break-in, not by the packing itself.
Installing braided compression packing correctly takes about an hour, and most of that hour is spent waiting. The steps themselves are simple. What separates a set that lasts a year from one that fails in a week is whether anyone respected the break-in period and whether the gland was left alone afterward.
SEPCO braids more packing than anyone in the world, all of it in Alabama. That means we also see more failed packing than most, and the pattern is consistent: the packing rarely fails on its own. It gets installed in a hurry and then tightened until it stops leaking, which is the one thing you must not do.
Why does packing need to leak?
This is the part that gets argued about, so it’s worth settling first.
Braided compression packing is a dynamic seal running against a moving shaft. That contact generates friction heat. The small amount of fluid passing through the packing does two jobs: it carries that heat away, and it lubricates the interface between the packing and the shaft or sleeve.
Take the leakage to zero and both jobs stop. The packing runs dry, the temperature climbs, the braid hardens and glazes, and the shaft or sleeve gets scored. At that point you’re not running a seal anymore — you’re running a dry bearing made of braided fiber against a rotating shaft.
The visible consequence is that the next set fails faster than the last one, because it’s now sealing against a damaged surface. That’s the death spiral most plants are in with packed pumps, and it almost always started with someone cranking down a gland to stop a drip.
There are zero-leakage packing designs. They work differently and depend on a flush or lubrication arrangement to handle the heat. If that’s what you have, follow its specific instructions. For conventional braided packing in a standard stuffing box, leakage is a design requirement.
What do you measure before installing packing?
Lock out and tag out. De-energize, verify zero energy state, confirm the line is depressurized and drained.
Measure the stuffing box. You need three numbers:
- Shaft or sleeve outside diameter at the packing location
- Stuffing box bore inside diameter
- Stuffing box depth
Packing cross-section is half the difference between the bore and the shaft: (bore ID − shaft OD) ÷ 2. Depth divided by cross-section tells you roughly how many rings the box holds, which you then adjust for the gland follower and the lantern ring.
Don’t assume the packing that came out was the right size. It frequently wasn’t.
Inspect the shaft or sleeve. Run your fingernail along it. Scoring, grooving, or a worn band at the packing location means the new set is sealing against a damaged surface, and it will leak no matter how well you install it. A grooved sleeve is a replacement, not a judgment call.
Measure runout at the packing location. Packing tolerates more shaft movement than a mechanical seal does, but not an unlimited amount. Excessive runout works the packing on every revolution and shortens the set’s life.
Note the flush port location. You’ll need it when you place the lantern ring.
How do you remove old packing?
Pull every ring. All of them.
Use a flexible packing extractor and work each ring out individually. Leaving one hardened ring at the bottom of the box is one of the most common installation errors we see — the new set never seats properly against it, and the first thing anyone does when it leaks is tighten the gland.
Check the bottom of the box for a ring you missed before you go further. If the old packing came out in pieces, count what you removed against what should have been in there.
Clean the bore. Residue, scale, and compacted fiber all have to come out.
How do you cut packing rings?
Cut each ring individually on a mandrel the same diameter as your shaft or sleeve, or wrap the packing directly around the shaft itself.
Don’t cut a stack from a tightly wound coil. The rings on the inside of the coil will be undersized and the ones on the outside oversized.
Butt cuts, square, for most braided packing. Some applications call for a skived or mitered joint — check the installation instructions for your specific packing. A properly cut ring closes with the two ends meeting cleanly, no gap and no overlap forcing it open.
Cut to length, not to feel. A ring cut slightly long will buckle when you seat it, creating a high spot that wears unevenly from the first revolution.
How do you install packing rings?
This is the step most often rushed, and rushing it is the second most common cause of early failure after over-tightening.
One ring at a time. Install a ring, then seat it fully against the one below using a split bushing or tamping tool before you install the next. Do not drop four rings into the box and compress them all with the gland.
Here’s why it matters: packing compresses along its length, and the gland’s force dissipates as it travels down the stack. If you seat the whole stack at once, the top ring takes most of the load and the bottom ring takes almost none. You end up with one over-compressed ring doing all the sealing and the rest contributing nothing — which is also why that top ring burns first.
Stagger the joints. Rotate each successive ring so its joint sits 90° from the one below. Joints lined up create a leak path straight through the set.
Work each ring in squarely. A ring that goes in cocked stays cocked.
Where does the lantern ring go?
If the box has a lantern ring, its position has to line up with the flush port after the packing is compressed, not before.
The stack shortens as you seat rings and again when the gland is set. A lantern ring placed level with the port during installation will sit below it by the time you’re running, and the flush never reaches it. That’s a dry-running set with a flush line connected to nothing.
Count your rings carefully and position the lantern ring high enough to account for compression. If you’re unsure how much travel to allow for your packing, that’s worth a call rather than a guess.
How tight should the gland be?
Finger-tight, and that’s all.
Bring the gland nuts down evenly, alternating sides, until they’re snug by hand. The gland follower should enter the stuffing box slightly — if it’s bottoming out before it contacts the packing, you’ve got the wrong ring count.
Leave take-up available. You’ll need room to adjust during break-in and over the life of the set. A gland that’s already run out of travel on day one has nowhere to go.
Rotate the shaft by hand. It should turn with some drag but without binding.
How do you break in new packing?
Everything before this point is preparation. This is where the set’s life gets determined.
Start with it leaking freely. When you first start the equipment, the packing should leak substantially — a stream, not a drip. This looks wrong and it alarms people. It is correct. You are going to bring that stream down to a slow drip over the next hour, and the gap between where you start and where you finish is supposed to be large.
Tighten in small increments. Bring the gland nuts down a fraction of a turn at a time — a flat or so — alternating sides to keep the gland square.
Wait between adjustments. Ten to fifteen minutes. The packing needs time to consolidate and the temperature needs time to stabilize. If you tighten continuously you’ll be chasing a reading that hasn’t settled, and you’ll overshoot.
Watch temperature, not just leakage. Check the stuffing box with the back of your hand. Cool to warm is right. Hot means too tight, regardless of what the drip rate looks like.
Stop at a steady drip. Not a stream, not a stop. A consistent, countable drip.
Break-in typically takes thirty minutes to a couple of hours. It cannot be done in five minutes, and a set rushed through break-in will not recover later.
How much should pump packing leak?
SEPCO guidance is roughly 10 to 12 drops per minute for a typical pump, but the right figure varies with shaft size, speed, and pressure.
A more reliable field test than counting drops: the leakage should be cool enough to hold your hand in, and the stuffing box should not be hot. If the drip rate looks correct but the box is hot, it’s too tight.
Expect to make a small adjustment in the first day or two as the set settles, then far fewer after that. Packing that needs constant adjustment is telling you something — usually about the shaft surface or the ring count.
Why does packing fail?
In rough order of how often we see them:
- Over-tightened during break-in or after. The dominant cause by a wide margin.
- Old rings left in the box. The new set never seats correctly.
- Installed as a stack rather than ring by ring. Uneven loading, top ring burns.
- Wrong cross-section. Nobody measured.
- Lantern ring misaligned with the flush port. Flush goes nowhere.
- Joints not staggered. Straight-through leak path.
- Worn or grooved shaft not addressed. No packing seals against a damaged surface.
- Wrong packing for the service. Chemistry, temperature, or speed outside the material’s range.
Seven of those eight are installation and maintenance decisions, not product problems. That’s consistent with what the wider reliability literature says about human factors in seal failure.
Choosing the right material for the service handles the eighth. Our compression packing line covers the common industrial services, and if you tell us the chemistry, temperature and speed we’ll tell you which style fits.
Frequently asked questions
How much should pump packing leak?
SEPCO guidance is roughly 10 to 12 drops per minute for a typical pump, though the right figure varies with shaft size, speed, and pressure. A good field check: the leakage should be cool and the stuffing box should not be hot to the touch.
How many rings of packing do I need?
Divide the stuffing box depth by the packing cross-section, then adjust for the gland follower and any lantern ring. Most pump stuffing boxes take four to six rings. Measure rather than copy what came out.
Should I stagger packing ring joints?
Yes. Rotate each ring 90° from the one below it. Aligned joints create a continuous leak path through the set.
Can I add one ring instead of replacing the whole set?
It’s a common shortcut and a poor one. The old rings are already compressed and hardened, so the new ring takes all the gland load and does all the work. Replace the set.
Why does my packing keep burning up?
Almost always because it’s too tight. If it’s correctly adjusted and still burning, check the shaft surface for scoring and verify the flush is actually reaching the lantern ring.
Should I use packing or a mechanical seal?
It depends on the service. Packing tolerates shaft movement, abrasives, and imperfect equipment better than a mechanical seal does, and it’s cheaper to maintain with in-house labor. A mechanical seal is the answer when the leakage itself is unacceptable — hazardous product, emissions limits, or a process that can’t tolerate dilution. We’ll tell you honestly which fits your application, including when the answer is a seal.
What is the break-in period for new packing?
Typically thirty minutes to a couple of hours, starting with free leakage and tightening in small increments with a wait between each. The set cannot be brought to its final adjustment in one pass.
Find Your Sealing Solution