Hydraulic Hose Operating Pressure

I'd go directly to the source and not rely on hear-say opinions.

You have your internal safety people, your insurance carrier, local, state and federal (OSHA) agencies to satisfy also.

Hydraulic Hose, Fittings and Equipment - Parker

Parker - Engineering Your Success - Motion Control Technology ...

The working pressure should be the max pressure attained in your process that the hose will be expected to contain.....The safety factors are for possible failures that can or might result in pressures exceeding working pressure but not resulting in catastrophic failure(min burst pressure)....and can be used as a safety benchmark in determining hose robustness under certain operating conditions and environments....

"I'd go directly to the source and not rely on hear-say opinions."

And you know what we (my mechanical guy basically) in the past found when we asked folks about this? None of them would say "this hose with an operating pressure of 5000psi can be run occasionally at 7500psi without problems", but they would say "we proof the hose at 2x and found during testing that the burst pressure is typically about 4x". We've gotten the same type of comments when asking distributors about fittings (in particular SS versus Titanium).

Which, up until now is why we've occasionally been running over the operating pressure. If I had to guesstimate, I'd say some -16 hoses we have that are rated to 6000psi have seen a few thousand hours at 5000psi and probably a few hundred at 7500psi.

You want too much.

There's a reason hose guys don't tell guys like you that "the hose is fine up to 7,900 PSI" because you would then feel that you have license to, "pump 'er up to 9,000 Bobby, it'll take it for a few minutes."

That's an exaggeration of course, but the manufacturer will not suggest that their product can be run at any pressure that they are not sure they can guarantee will not fail.

I'm also not suggesting that you would put anyone in danger. Attorneys can find intent in many places when they're looking for $.

Had the same problems when trying to get manufacturers to certify their products for space flight. Different issues, but limiting liability is the name of the game in both cases.

Good luck.

<edit> I see now that I've repeated some of Gene's post's cautions.

If the hose is expected to operate at 7500psi, then it is no good having a hose with a maximum working pressure of 5000psi; the selected hoses are wrong. Do not operate the plant. Go back to the hose supplier and replace the hoses with ones of the correct pressure rating before restarting it.

An accident investigator will call at the facility at some point otherwise.

Excellent answer, MrGeneRall. I would only add that final installed geometry and movement can degrade a hose fast. Pressure pulses and their frequency can also play havoc. Some times even the 4:1 factor is not a warranty that a hose assembly will meet the projected life. An experienced hose vendor, with the proper credentials will always check a large number of aspects before recommending a hose replacement, unless it is a very common (and known) one. Amclaussen.

Wow! . . . Never put 400 Amps on a 200 amp rated cable, 200 Watts into a 100 watt rated speaker, and especially 7500 psi on a 5000 psi rated hose. the later of which will generally involve spraying high pressure liquids or steam in any number of directions potentially causing injury or death. Wow!!

"Can anyone decipher what is really meant by operating pressure and safety factor, etc? My googling hasn't given me a definitive answer on this."

No need to decipher anything. Look at Parker catalog 4400. It states that hose burst pressure is typically 4X published working pressure. That's your ultimate safety factor.

"No need to decipher anything. Look at Parker catalog 4400. It states that hose burst pressure is typically 4X published working pressure. That's your ultimate safety factor."

Why not call a 5000 psi 4:1 safety factor hose a 6666 psi 3:1 safety factor hose...which is basically what my mechanical guy is doing.

In this case what you're really asking is...is it safe to work with a 3:1 "ultimate" (based on burst pressure) safety factor? The answer is no. There are many reasons why Parker has a minimum 4:1 s.f rating on their hose. They specifically state in their catalogs to not use the "burst pressure" rating as a guide for sizing your system. The burst pressure values are obtained through controlled testing. Real world applications are not controlled and that's why they explicitly state to never exceed rated working pressures.

I thought I'd add some more to this thread

"Real world applications are not controlled and that's why they explicitly state to never exceed rated working pressures."

I still haven't read what my mechanical guy has referenced that says 3:1 is ok, but in the course of the past few weeks we've had quite a few discussions about pressure ratings. For our application, the pressure for all intents and purposes IS controlled. We operate at 5000psi for all of the testing except proof testing where we do expect to see small "shocks" (in the 50-150psi range) as (unloaded) actuators are commanded in and out and valves have their solenoids turned on and off. However the 7500psi proof tests are are static. I think that is how all the people involved with this system let us get to the point where we are using lower rated hoses for our purposes.

Regardless, we are going to eat the few months delay to get properly rated hoses.

Some folks brought up an interesting point, the fittings on the components are only rated for 5000 psi operating pressures, and yet the acceptance test specifically calls for testing them at 7500psi for proof. This doesn't s jive with what you guys are saying regarding operating pressure, that it shouldn't be exceeded. Thoughts?

If your test stand will be operating at 7500psi on a regular basis then your system should have fittings rated for 7500psi.