FPSI logo

Fluid Power Safety Alerts

(Ref. No. SA-031)

The LETHAL STRIKE DVD is now available!


"Home-made" hydraulic test connectors could kill you! -
by Rory S. McLaren

There is nothing like a good old home-cooked meal, or a home-baked apple pie. However, when it comes to hydraulic test equipment “home-made” simply belongs in the kitchen – especially if you value your life, or that of your colleagues!

I recently had the opportunity to visit the equipment service and repair workshop at a very large open-pit mine. The responsibility of the workshop personnel was to keep the mine’s very large fleet of mobile machinery operating safely and efficiently. The extensive fleet consisted of, blast-hole drill rigs, front-end loaders, bulldozers, and, very large haul trucks.

While touring the shop I noticed a number of what appeared to be “home-made” hydraulic pressure-test connectors laying on a workbench.

These extremely crude “test” devices were made out of Code 61 and 62 connectors, which had been cut off a hose-end crimp fitting, a piece of 3” diameter steel tube, a 3/8”-NPT pipe fitting, and a piece of round plate, which had been drilled and tapped to accept the 3/8”-NPT hydraulic fitting.

The components were crudely welded together to form, what I learned, was a brake-pressure test device to test vehicle brake pressures – up to 3000-PSI (207 bar).

The supervisor (tour guide) explained to me that the devices were made by a mechanic who was neither a qualified welder or a machinist. To add insult to injury, the mechanic also had no formal training in hydraulics – he was obviously completely naïve to the hazards he had inadvertently created for he and his colleagues.

I wasn’t surprised at the all too familiar answer when I asked the supervisor why the pressure test apparatus was “home-made” rather than being properly engineered and manufactured. His answer was one I had heard many times before - the "maintenance manager" wasn’t interested in purchasing hydraulic test equipment of any sort because “nobody knew how to use it anyway,” and, because it was generally too expensive! This coming from a mine that had an investment in mobile equipment exceeding fifty million dollars!

This is not the first time I have seen “home-made” connectors. There are literally tens of thousands of them being used daily in plants across the country – most are hopelessly under-designed for the task – they are veritable accidents looking for a place to happen!

One of the most common home-made connectors is the inline JIC pressure-test connector (Figure 1). It consists of a standard JIC “T” with a modified cap screwed onto the rise. To facilitate a pressure gauge, the cap is drilled and tapped to accept a 1/4” NPT male connector.

Unfortunately, the cap is so thin that it leaves space for no more than 1.5 threads to secure the test gauge or adapter.

Maintenance personnel are using these types of connectors daily to perform pressure checks in hydraulic systems operating at pressures up to 5000-PSI (345 bar).

Figure 1

People are getting hurt! -
A millwright was struck in the face and suffered a severe laceration when a fitting “blew-out” while he was performing tests on a hydraulic system.

An investigation into the cause of the failure determined that the "defective fitting" failed because it was subjected to pressures exceeding 3000-PSI (207 bar). After all, it was nothing more than a black–pipe fitting with a maximum pressure rating of 250-PSI (17.2 bar).

Not only do hydraulic fittings have maximum operating pressure ratings, but they also have safety factors, which are usually no less than 4:1. This simply means that if the maximum pressure rating (working) is 3000-PSI (207 bar), then the minimum burst pressure is 3000-PSI (207 bar) (maximum working pressure) times 4 (safety-factor), which equals 12,000-PSI (827.6 bar) – the minimum burst pressure.

The seriousness of the problem is masked by ignorance -
The problem doesn’t appear, at the surface, to be serious because the fluid power industry escapes the watchful eye of corporate safety personnel – including OSHA (because hydraulics is yet to be recognized by any institution as an occupational hazard). This simply means that you will be hard-pressed to find a company in America that includes hydraulics in its near-miss reporting program.

If corporate safety personnel were trained in all facets of occupational safety they would NEVER allow untrained personnel to work on their respective company’s hydraulic systems without making sure that they were properly trained. Also, they would be able to recognize these, and other, hazards associated with hydraulics.

This logic extends to maintenance technicians who, through proper training, will also be empowered to recognize these, and other hazards associated with hydraulics.

Why does this problem exist? -
It’s very simple! Any living, breathing soul can work on and around hydraulic systems without any formal training whatsoever – there are absolutely no rules!

Also, "systemic safety", that beyond pressure ratings of components, is never considered when designing hydraulic systems. Unfortunately, life-saving devices for checking pressures are deemed “expensive” and thus are ignored in design.

Please, don’t rush to judgment! Before you berate me about my negative comments, ask yourself if the hydraulic systems you design comply with OSHA’s lockout procedures with respect to de-energization and verification – probably not! If they do, you fit into the less than .01%category - and you have my respect!

These ongoing oversights by hydraulic system designers force people to be creative when needing to test hydraulic systems – bearing in mind that when production goes down everything is done in haste.

Production managers will not, and should not, have to deal with the fact that when a production machine breaks down they have to wait for hours, and sometimes days, for untrained maintenance personnel to "hack" components together to make-up hydraulic test fittings. Poor maintenance management forces maintenance personnel to work unsafely and, inefficiently.

As far as procuring the proper test connectors while the machines are operating – that would be classified as “pro-active.” The vast majority of hydraulic “maintenance” is done on a “reactive” basis.

People who are not properly trained to troubleshoot hydraulics will not know what they need until they need it, which forces them to “compromise their way out of the problem!”

The practice of making test connectors on an “emergency only” basis must be stopped in its tracks – before someone dies! Hydraulic test connectors can undergo extreme pressure and force conditions and MUST therefore be designed and manufactured by competent personnel.

People who troubleshoot hydraulic components and systems MUST be properly trained. Under no circumstances should an untrained person be allowed to troubleshoot hydraulic components and systems. Untrained personnel are always at risk of suffering severe injury or death.

I urge you to make the practice of making “home-made” hydraulic pressure-test connectors unlawful in your company – with immediate effect!

If your supervisor "looks the other way" when you are forced to "design and manufacture" hydraulic test connectors, find a new job! Rather you at home with your family without a job, than the familiy at home without you - never forget that!

The Fluid Power Safety Institute welcomes constructive comments reagrding our safety alerts -
Your comments are welcome.


Rory S. McLaren
Fluid Power Safety Institute


About the FPSI™ | Safety Alerts | FPSI™ Resources | Safety Products | Industry Safety Links | Family/Community Safety | Site Map | Contact FPSI™ | HOME

Copyright © 2002-2006 - FPSI™