When Every Hydraulic Fitting in the Building Is Apparently Machined Wrong

"No amount of evidence will ever persuade an idiot."

Today at the Mondak Equipment hydraulic counter, we got a pretty impressive demonstration of exactly how that works.

A guy came in with a brass adapter and one of our -6 FJ hydraulic crimp fittings.

His complaint was simple:

Our fitting had been machined wrong because it wouldn't screw onto his adapter.

Fair enough. If there's a problem with something we sell, we want to know about it.

So we looked at his adapter.

Brass.

Flare connection.

Not the same thread.

Not the same seat.

Not the same fitting.

In fact, what he had was a brass 45-degree flare-style fitting used in plumbing and similar applications, and the hydraulic fitting he was trying to put onto it was a 37-degree JIC connection.

There wasn't anything wrong with the hydraulic fitting.

It was simply the wrong mating connection.

That should have been the end of the story.

It wasn't.

"I Got It in the Hydraulic Section"

He explained that his brass adapter had come from the hydraulic section at the local hardware store.

Interesting.

Mostly because the local hardware store doesn't have a hydraulic section.

They do have a plumbing section.

And somehow, sitting right in front of us, was a brass plumbing-style flare adapter.

You could almost see the mystery solving itself.

Except he wasn't convinced.

The problem, according to him, was still our fitting.

So We Grabbed Another One

Maybe there was somehow a manufacturing problem.

No problem.

We went to the shelf and grabbed another -6 female JIC hydraulic crimp fitting.

Same result.

It wouldn't screw onto his adapter.

So we grabbed another.

Same thing.

Then we showed him more of our -6 FJ fittings.

Same threads.

Same 37-degree JIC seat.

Same properly manufactured hydraulic connection.

At this point we had multiple hydraulic fittings sitting on the counter, all matching one another perfectly.

His brass adapter matched none of them.

The conclusion seemed fairly obvious.

His conclusion?

Apparently every -6 FJ hydraulic fitting we had in stock had been machined wrong.

All of them.

Not the one brass adapter from the nonexistent hydraulic aisle.

The entire inventory of actual hydraulic fittings.

That was the problem.

There Comes a Point Where the Evidence Gets Pretty One-Sided

Let's review.

The adapter was brass.

It was a different style of flare connection.

Our hydraulic fitting wouldn't even start onto it.

Multiple identical -6 FJ hydraulic crimp fittings wouldn't start onto it either.

All of our hydraulic fittings matched each other.

We could measure the threads.

We could compare the seats.

We could physically show the difference.

And the hardware store where it came from doesn't even have the hydraulic section he remembered buying it from.

It does have plumbing.

But somehow the only reasonable explanation left was that an entire batch of hydraulic fittings had all been manufactured incorrectly in exactly the same way.

At that point you're not really troubleshooting a fitting anymore.

The Part That Actually Isn't Funny

This particular mismatch was obvious because the fittings wouldn't screw together at all.

That's a good thing.

The situation gets considerably more dangerous when somebody finds two mismatched fitting standards that are just close enough to get a few threads started.

That's when we hear:

"But it screws on."

That doesn't prove anything.

Different fitting standards can have similar-looking threads while using completely different sealing surfaces, thread forms or seat angles.

A common JIC hydraulic connection uses a 37-degree flare.

Many brass flare connections use a 45-degree flare.

If the wrong components are forced together, you can deform the sealing surfaces and create a connection that was never designed to hold hydraulic pressure.

And we're not talking about household water pressure.

Hydraulic systems commonly operate at thousands of PSI.

A failed connection can spray high-pressure oil, separate unexpectedly or create a fine leak capable of causing a hydraulic injection injury.

So if two hydraulic components don't belong together, making them fit isn't fixing the problem.

It's creating another one.

This Is Why Hydraulic Fittings Are Identified, Not Guessed At

At Mondak Equipment, we don't identify a connection based on what aisle someone remembers buying it from.

We look at the fitting.

Thread diameter.

Thread pitch.

Seat angle.

Sealing surface.

Male versus female.

Straight versus tapered thread.

O-ring location.

Metric versus imperial.

Material.

Application.

Those differences become even more important when you're dealing with JIC, ORFS, NPT, BSPP, BSPT, DIN, JIS, VOSS, metric, Komatsu-style connections and the many other fitting styles in use today.

Some of them look incredibly similar.

That doesn't make them interchangeable.

A thread gauge doesn't care about your opinion.

A caliper doesn't care where you think you bought the adapter.

And a 37-degree seat doesn't magically become 45 degrees because you're really confident about it.

Sometimes the Fitting Really Is Wrong

We're not above being wrong.

If we supply the wrong fitting, we'll correct it.

If a fitting has a manufacturing defect, we'll replace it.

If something doesn't look right, we'll measure it and figure out why.

That's part of doing the job correctly.

But when every -6 FJ hydraulic fitting on the shelf matches every other -6 FJ fitting on the shelf, and none of them will screw onto the one brass adapter somebody brought in from the "hydraulic section" of a store that doesn't have a hydraulic section...

There might be another possibility worth considering.

Maybe every hydraulic fitting in the building isn't machined wrong.

Maybe you brought us a plumbing fitting.

Get the Right Fitting the First Time

At Mondak Equipment, we stock hydraulic hose, crimp fittings and adapters for common and hard-to-find connections, and we take the time to identify what you actually have before building a hose or handing you an adapter.

Whether it's JIC, ORFS, NPT, DIN, BSPP, JIS, VOSS, Komatsu-style or something less common, our job is to match the connection correctly, not make something "close enough" fit.

If you're unsure what fitting is on your equipment, bring it in or bring us the hose and mating connection.

We'll measure it, identify it and get you the correct hydraulic connection for the application.

Because when hydraulic pressure is involved, the right fitting isn't a matter of opinion.

It's a matter of safety.