A Race Against the Hole: Keeping a VentureTech ST80 HPU Running During a Casing Job in Alexander, ND

That was the situation when a customer called Mondak Equipment and Hose about the hydraulic power unit (HPU) supplying a VentureTech ST80 Iron Roughneck in Alexander, North Dakota.

The Iron Roughneck itself wasn't the problem.

The problem was the HPU providing the hydraulic power for the ST80.

The rig was in the middle of a casing operation, and the hole was still open. They had to get the casing in the hole before the hole started collapsing.

The cement crew was waiting. A state official was on location to observe the operation. The rig needed to keep moving.

And then the HPU developed a hydraulic failure.

It became a race against the clock.

The Problem Wasn't Where We First Thought

Mondak responded to the location and started diagnosing the ST80 HPU.

The HPU uses a three-section Honor gear pump mounted on the back of the HPU. Each section of the pump serves a different purpose within the system.

One section operates the auxiliary functions, including the link cylinders and grabber.

The second section is the charge pump for the Sundstrand system.

The third section operates the hydraulic oil cooler.

Understanding what each section of the pump does was important because we needed to determine exactly where the hydraulic problem was occurring.

During our initial diagnosis, we found debris in the relief valve inside the valve body.

Our first suspicion was that the relief valve had failed.

But rather than simply replace a valve and hope for the best, we wanted to determine what the pump was actually doing.

The Pressure Test Changed the Diagnosis

Because the pump is a gear pump, it cannot simply be deadheaded against a closed valve.

We installed a pressure gauge and valve and carefully restricted the flow enough to determine whether the pump could build pressure.

It couldn't.

There was essentially no pressure.

That told us the relief valve wasn't the root cause.

The problem was with the pump itself.

The Gear Pump Had Shredded Itself

Further inspection showed that the gear pump had essentially shredded itself internally.

And all of that debris had gone through the hydraulic system.

This was no longer simply a matter of replacing a bad relief valve.

When a hydraulic pump comes apart internally, the resulting debris can travel through the hydraulic system and potentially affect valves, hoses, coolers and other components.

We also discovered that the pump had recently been installed by another company and was already a used pump when it was installed on the machine.

The customer needed a replacement pump.

The replacement pump was approximately three days away.

Normally, that might mean waiting.

This wasn't a normal situation.

The Hole Wasn't Going to Wait

The rig was working with an open hole.

The longer the casing operation was delayed, the greater the concern that the hole could begin to collapse before the casing could be set.

The cement crew was waiting.

The state official was waiting.

The customer was waiting.

And the hole wasn't going to wait for a parts shipment.

We needed to find a way to keep the auxiliary functions operating until the correct pump arrived.

Protect the Failed Pump. Find Another Hydraulic Power Source.

We disconnected the failed pump from the valve body and looped it back to tank.

This kept the failed pump out of the working hydraulic circuit and helped prevent it from being forced into a condition where it could seize while we worked on the temporary fix.

Then we looked at what the auxiliary system actually needed.

We only needed approximately 6-12 GPM at 1,800 PSI to operate the required auxiliary functions.

That opened the door to some unconventional solutions.

At one point, we were even looking at finding a log splitter that could provide the hydraulic flow and pressure we needed.

Because in field service, sometimes the question isn't:

"What was originally designed for this?"

The question is:

"What can safely accomplish the job right now?"

Then the rig owner mentioned that he had something called "Bob."

Could we use Bob?

Meet Bob

We figured out that Bob wasn't a person.

Bob was a Bobcat Toolcat with auxiliary hydraulics.

And the Toolcat had what we needed.

So the owner went and got Bob.

Our technicians built the hydraulic hoses needed to connect the Toolcat's auxiliary hydraulic system to the VentureTech ST80 HPU's auxiliary functions.

We essentially used the Toolcat as a temporary hydraulic power source.

It wasn't a permanent repair.

It wasn't intended to replace the ST80's HPU.

It simply had to do one job:

Keep the auxiliary functions working long enough to get the casing in the hole.

Sometimes You Have to Adapt

This is what field service looks like in the real world.

The solution isn't always sitting on a parts shelf.

Sometimes you have to diagnose the failure under pressure.

Sometimes you have to understand the entire hydraulic circuit.

Sometimes you have to build hoses on site.

Sometimes you have to protect a failed component while you wait for the replacement.

And sometimes you have to figure out how to make a Bobcat Toolcat named Bob keep an oilfield operation moving.

The replacement pump was on the way.

But the customer couldn't wait three days to get back to work.

So we found a way to keep the auxiliary hydraulic functions operating while they waited.

The goal wasn't to make Bob the permanent fix. The goal was to buy the customer enough time to get the casing in the hole.

And in this case, time was exactly what mattered.

When the Job Can't Wait

Oilfield equipment doesn't always break down when it's convenient.

It happens when the rig is working.

It happens when crews are already on location.

It happens when an open hole is waiting for casing.

And it happens when a three-day parts delay isn't an option.

That's why field service requires more than knowing how to replace parts.

It requires technicians who can diagnose the actual failure, understand the hydraulic system, build what is needed in the field and adapt when the original plan isn't going to work.

At Mondak Equipment and Hose, we provide mobile field service, hydraulic diagnostics, hydraulic repair and hose fabrication for oilfield equipment throughout the Williston Basin.

When a specialized HPU goes down, our technicians work to understand why it failed, protect the rest of the system and find a practical way to keep the customer's operation moving.

Because when you're working over an open hole, you don't always have three days.

Sometimes you have to figure it out now.

Alexander, ND | Williston Basin

Mondak Equipment and Hose
Hydraulic Repair • Field Service • Hose Fabrication • Oilfield Equipment Repair