5000psi Hydraulic Piping 1

[BoiseENG]

Sorry if this is the wrong thread, but I'm just looking for help.

I'm trying to find out if there are any standards out there (AWS, ASME, ASTM, ISO, etc.) that specify the requirements for the finish (grinding, pickling, etc.) and welding of 5000psi hydraulic piping in a field installation/assembly.

6000lb full socket weld fittings will be used and all pipes will be butt welded as necessary.

Piping material is sch40 carbon steel.

Any help would be greatly appreciated.

 

[zdas04]

"Sched 40 carbon steel" gives you a MAWP of 1500 psi at 100F in 2-inch. In 1-inch it is up to 2100 psi. Even at 1/8 inch it is only rated at 3500 psi at 100F. If you are planning on 6000 psi, why would you specify S40?

David

 

[BoiseENG]

Sorry. That was a typo.

Piping is SCH80 carbon steel.

 

[zdas04]

Sched 80 gets you all the way to 2500 psi in 2-inch (only 4,800 psi in 1/8 inch). From your first two posts I would guess that you are a bit over your head. You need some considerable help with the basics (e.g., what pipe size/schedule is required for the flow and pressures of the system) before you can get meaningful answers about pickling and such. Doing a great job on the stuff you asked about and a horrible job on the rest is very much like lacquering a turd--it is all pretty an shiny, but still a piece of crap.

David

 

[BoiseENG]

David,
This was a "research" topic my boss asked me to do for him. He's a PE so I was assuming that he had already done the calcs for the pipe thickness. Maybe he hasn't. Not really the issue I was getting at though. I need help finding codes and/or standards for the field installation that I can reference. My problem wasn't the design of the system, just finding the applicable codes/standards.

I realize from your questions/answers that there are some unknowns here based on the original information I supplied. I've asked for more info from my boss and will post once I have it. Do you have any idea of codes/standards that I could explore while waiting for this info?

 

[EdDanzer]

Seamless schedule 80 pipe has a higher working pressure for hydraulics than 4800 psi. We make hydraulic cylinders that frequently see 10,000 to 15,000 psi pressure spikes and operate at 4500 to 5000 psi working pressure. After much experimentation we found that the best life is ½” schedule 80 seamless pipe welded to ports and manifolds or DOM tube with .035 E80SD2 solid wire and a 90-10 shield gas, use a 100°F localized preheat if possible. The tubes are cold bent to eliminate weld elbows as each weld is a potential leak. Thick wall DOM has to be hot bent which reduces its strength and will not last as long as the pipe. We have used ¾ and 1” seamless sch.80 on excavator plumbing with good results. Be sure any fittings you use are not made from free machining material. If the finish is smooth and shines it is probably a free machining material and you will have weld failure. For high pressure application CD1018 or HR 8620 are the best materials for ports and manifolds that have to be welded.

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com

 

[MJCronin]

Boise...

You are aware of the fact that "6000lb" fittings are not rated for 6000 psig service ?....Right..?

See ASME B16.11 for more information on allowable pressures for socket welded and threaded fittings. You should know that "9000lb" fittings also exist.

You also stated about your boss: "He's a PE so I was assuming that he had already done the calcs for the pipe thickness."

As an ancient PE, I find both your faith in him and his lack of competent direction deeply disturbing....

Things can blow up....

-MJC

 

[unclesyd]

Here is a little information from Tube-Mac that may help you understand the process of hydraulic piping design, hoping you will realize your limitations in this process. This not to question or criticize your effort, all we want is for you to get it right.

I concur with the above statement concerning you need to get some help from someone well versed in the mechanics and art of hydraulic system and piping design. I've seen some very bad life altering accidents from hydraulic systems at far less pressure than you are working with.

http://www.tube-mac.com/designers.asp

 

[zdas04]

EdDanzer,
Any pipe MAWP is based on an Engineer's willingness to accept risk. It always starts with a version of Barlow's formula to calculate hoop stress and then compares the calculated stress to the manufacturer's SMYS specification. Everyone uses a different acceptable value for this ratio. One of my client's uses 20%. Another 30%. I've rarely seen anyone use a number much higher than 40% on purpose.

The MAWP values I mentioned above are the ones published in ASME B36-10 for 100F. I don't recall their allowable hoop stress as a percentage of SMYS.

The link that unclesyd provided has higher values for MAWP than ASME has. Different thresholds, different materials. DOM tubing has a 100,000 psi SMYS, so 1-inch 0.179 wall (sched 80) with a 25% allowable hoop stress would have a MAWP of 6500 psi as stated in the linked table if the corrosion allowance is 1/128 inches. Using the ASME Tables and the API 5L pipe that they based the calculations on would have a MAWP of 3500 psi with their corrosion allowance assumptions.

My rule on these boards is that if someone specifies something like "Sched 40 Carbon Steel" then I assume they know what they are talking about and don't assume that they really mean DOM tubing even though that would be a more common choice at these pressures.

While some might find this to be an interesting review of MAWP techniques, it is really irrelevant to the OP's question. I'm not interested in his original question so I guess I'll stop now.

David

 

[unclesyd]

zdas04,
Looking in their catalogue pipe section it gives the allowables used for the MAWP used in their tables.

TMP 52CD A519 CD 24,000 psi
TMP 44HR A519 Sm 20.000 psi
TMP 106HR A106-B Sm 20,000 psi
not in tables
TMP 46CD 34,000 psi

How do these values compare with ANSI 31.1?

 

[vpl]

BoiseENG:

Ah the dangers of too much (and not enough) information!

You want to know if there are any standards that apply to finishing and welding.

The short answer is yes. The longer answer is that we'd need different information than what you've supplied.

An easier way to find out might be to talk to your local authorized inspector as the required standards of use differ by state, country, locality, and field. Otherwise it's a game of 20 questions while we try to guess which of the multitude of standards apply to your situation ... or where we go off on tangents because the rest of the information doesnt make sense.

Patricia Lougheed

******

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[Giuliano81]

I'm a new "material man" and i don't understand which is the problem.

I suppose that if I design a piping system using the ASME B31.3 i'll follow the ASME B31.3 for the welding spec.

If this sentence is right, why don't Boise ask to his PE (what does it mean PE???) what kind of manual he used to choose the SCH of the piping system?

 

[BoiseENG]

All,
Here is all of the information I was unable to give on my original post:
Material = ASTM A312 Grade B - 304L Stainless Steel
Schedule = XXH, 2-1/2" piping (2.875" OD, .552" wall)
Using the thick walled cylinder equation, a safety factor of 4 and the MAWP of 5,000psi, the resulting stress is well within the tensile strength of the material. Also there are no welded branches on the system. All fitting are to be butt welded - Hopefully this helps those with questions regading the design of the system (even though it really wasn't my original question).

I used the ASME B31.3 - Chapter 9 High Pressure Piping - to write most of my welding specification. There wasn't any information in B31.3 that required any pickling or other surface treatments that I had originally been wondering if I needed. I don't have access to the ASME BPV Code which could be applicable under the customer mandated high pressure classification of the hydraulic system - B31.3 states that anything under a class 2500 (6,000psi) fitting is not necessary high pressure unless it is mandated as such by the owner/engineer.

Does anyone have any experience with the actual installation of a system like this and any special surface treatments required or am I in the wrong form as most of you are looking for design criteria?

 

[TBP]

You guys all know that unless something has changed recently, the ASME pressure piping codes very specifically EXCLUDE hydraulics - and have since "Day One" right?

 

[BoiseENG]

TBP,
Is there a specific ASME code (or another code/standard out there - ISO, AWS, etc. - that you know of) that is meant specifically for hydraulic systems????

Thanks

 

[EdDanzer]

Here is the page for the NFPA pressure code.

http://www.nfpa.com/Standards/Standards_Details.asp?sid=ANSI/(NFPA)T2.6.1

R2-2001 (R2005)

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com

 

[TBP]

I'm not THE hydraulics guy, by any means. I have a friend - not an engineer - he's the guru at at big local fluid power supplier, who is, though. I've talked to him in the past about what codes apply to hydraulic piping. He doesn't know either. All the local TSSA (Ontario) inspector ever said was "We don't even look at hydraulic piping. It's got nothing to do with us."

The hydraulics book my buddy lives out of is "IPT's Industrial Hydraulics Handbook", by James A. Archer. It uses Barlow's formula. It's a small book, written for mechanics, that's a real time-saver.

http://www.iptbooks.com

 

[racookpe1978]

Back up and think twice - about the original problem, and about how you intend to attack it (materials (stainless or carbon steel, tube or pipe, small diameter (good for higher pressure, worse for flow over any measureable distance) or headers and longer pipes, connections and spec's.) The bosses' guidelines need themselves review by a hydraulic expert as well.

I'm troubled by the "simple" changes stated in the material and pipe callout: from carbon steel to stainless 304L, from Sch40 to Sched 80 to "Schedule = XXH, 2-1/2" piping (2.875" OD, .552" wall)".

Just throwing more metal (and a different kind of metal) at the weakest small symptom of one part of a design problem only assures you that you've overlooked (accidentally, but still overlooked nonetheless) a significant hidden problem elsewhere. Like connections or flex hoses or flushing and cleanliness or flow rate under use or ....)

 

[eadwine]

From the NAVCO Piping Datalog: hydraulic piping 4500#

1/2"-3/4" sch.160 grB smls. c.s.
1"-3" xxs grb smls. c.s.
4"-10" Calculate wall thk. smls. c.s.

At or above 6000 psi calculate wall thk.
wall thk. become specials

Fittings: utilize pipe bends of calculated thk.

Flg.'s special hydraulic: type 1 sq. or type 2 rnd.

gasket: copper. 1/16" to 1/8" thk.

bolting: a193-b7 w/a194 gr 2h nuts min.
bolt load tension: (int. area of pipe x int. press + gasket area x int. press. x 3)/ (no.of bolts x stress area ea. bolt)

And support & restrain this stuff like there is no tomorrow.