Grundfos Flange Kit 3/4 and 99313067: An Emergency Repair Field Guide

Quick note: if you got here looking for a 2024 Bentley GT, a woolly bear caterpillar, or the answer to 'what is skiing?', this isn't that page. It's about a small part that has rescued me from more weekend disasters than almost anything else: the Grundfos flange kit 3/4, sold under part number 99313067.

I'm the person who gets the phone call when a pump quits at 4:45 on a Friday. I've spent years coordinating emergency pump parts, and in my experience, the flange kit is the part people forget to order until the old one starts leaking. Here are the questions I keep answering.

What is the Grundfos 99313067 flange kit?

The short answer is that it's a factory replacement flange kit for 3/4-inch connections on selected Grundfos pumps. It should include the two flanges, a new gasket or o-ring, and the hardware needed to mount the pump flanges to your pipe system. I say 'should' because I've seen packaging vary over the years—some kits reuse the original bolts, and newer kits can look different.

Why does this matter? A tiny coolant hose can stop a powerful engine, and a 2024 Bentley GT doesn't get far with a loose radiator connection. The same principle applies to a pump: the flange kit is not the flashy part, but it's the part that keeps water where it belongs.

How do I know if a 3/4-inch flange kit fits my pump?

Start with the pump nameplate. You need the model number and serial number. A 3/4-inch flange kit refers to the pipe connection size, not the horsepower, not the motor frame, and not the distance between the bolts. I learned that lesson the hard way: my first year in emergency parts, I matched a flange by eye. It looked perfect. It was a 1-inch flange with a 3/4-inch adapter that a previous contractor had installed. Cost me a reorder and 48 hours of downtime.

Use the Grundfos Product Center at grundfos.com to verify the part number. If you have the old flange kit in your hand, the part number is stamped on the metal flange itself. That's the most reliable confirmation. But don't assume the number on the old flange is still current—check before you order.

Can I use a generic flange kit instead of the Grundfos one?

Sometimes. But 'sometimes' is not really the answer you want in an emergency. I've seen generic flange kits work fine on low-pressure systems. I've also seen them fail within a year on a hot water loop, and by the time someone calls me, the floor is wet and the loop is down. With a Grundfos pump, I'd rather get the Grundfos kit, part 99313067 if that's what your model needs. It costs a little more, but that difference is usually smaller than one service call (and that's counting the time you lose when the leak shows up).

There are also 'will-fit' kits that claim to match Grundfos part numbers. Some are fine. The trouble is, you can't always tell which ones. If you're under deadline pressure, is that a gamble you want to take?

Is paying for rush delivery ever worth it?

In one word: yes, when you're on the clock. In March 2024, a client called about a 99313067 flange kit for a heating pump in an office building. Standard ground shipping showed three days. Overnight air was $54 more. They paid the $54, and the part was on site at 9 the next morning. The alternative was an office building without heat for two extra days, and that costs a lot more than $54 in one morning of lost rent or tenant complaints.

I don't believe in paying rush fees for everything. If the pump is offline and there's no pressure in the line, standard delivery is fine. But when a system needs to be back online by a hard date, you're not paying for speed—you're paying for certainty.

Can I reuse the old gasket if it looks fine?

I don't recommend it. I've done it. It leaked at about 68 psi. The whole system was down while we took it apart again, and the 'saved' gasket ended up costing six hours of labor and a lot of bad words.

A flange kit is a service item. The gaskets compress after installation, and old bolts can rust. If you're replacing the flange anyway, use the new gasket and hardware that comes in the kit. Clean the sealing faces, tighten the bolts in a star pattern, and check for leaks when you bring pressure back up. If the torque values are listed in the Grundfos manual, use those. Don't guess.

Should I stock this part before I need it?

Yes, if you have a pump that uses it. The 99313067 is not expensive compared to the cost of an emergency service call (and I'm not just talking about the invoice—I mean your Saturday evening). A couple of years ago, the same client ordered the wrong flange kit three times in a month because they didn't have the part number on hand. After that, they put one on the shelf and never thought about it again.

People used to look at the woolly bear caterpillar to predict how bad the winter would be. I say: if you run a ski lodge, you don't need me to explain what skiing is. You need to know if your heating pump has a fresh flange kit before the first freeze. That's not a prediction—it's a checklist.

What if the 99313067 part number is backordered?

First, breathe. Then call a local Grundfos distributor instead of relying on an online stock status. Distributor inventory doesn't always show up on a website, and especially for a common 3/4 flange kit, they often have one sitting on a shelf. If the 99313067 has been superseded, they can give you the new part number.

This part number was accurate as of early 2024, but things change. Verify current availability and pricing before you budget around a fixed number.

How quickly can I get one if I'm really stuck?

If you call early enough in the day, a local distributor can sometimes have the part waiting for you the same afternoon. If they need to ship it, overnight freight is the most reliable option. In Q3 2024, we expedited a 99313067 to Pennsylvania with a 30-minute closing-time warning. The freight charge was $38, maybe $40, I'd have to check the exact cost. But the client's production line was estimated at $12,000 per day of downtime. That $38 paid for itself within the first hour.

When you're in a bind, the process is simple: check the pump model, call a distributor, confirm the part number and shipping option, and have the packaging ready. That's it.