Heavy Machinery loads on pipelines
Heavy Machinery loads on pipelines
(OP)
I need to determine the acceptability of external transverse loads exerted on pipeline as a result of construction and farming machinery crossing the pipeline at locations other than designated roads.
The calculation can be carried out for 900mm, 1200mm and 1500mm depth of covers as per API-1102. But there are some instances that depth of cover is 750mm. Figures 15 and 17 of API1102 (Highway Geometry Factor for Cyclic Circumferential/Longitudinal Stresses) do not cover 750mm DoC and as per Clause 4.5 of API1102, extrapolations beyond the design curve limits are not recommended. So calculation for 750mm DoC should be done using another method. i.e. Spangler method or etc.As far as I know there are various doubts on the validity of the Spangler method for high pressure steel pipelines.
Does anyone have a suggestion and/or guideline that can be used.
Thanks in advance
The calculation can be carried out for 900mm, 1200mm and 1500mm depth of covers as per API-1102. But there are some instances that depth of cover is 750mm. Figures 15 and 17 of API1102 (Highway Geometry Factor for Cyclic Circumferential/Longitudinal Stresses) do not cover 750mm DoC and as per Clause 4.5 of API1102, extrapolations beyond the design curve limits are not recommended. So calculation for 750mm DoC should be done using another method. i.e. Spangler method or etc.As far as I know there are various doubts on the validity of the Spangler method for high pressure steel pipelines.
Does anyone have a suggestion and/or guideline that can be used.
Thanks in advance





RE: Heavy Machinery loads on pipelines
First rule of Engineering is common sense. If you can't muster up any of that, this will be a tough business for you.
Normal soil cover WITHOUT ANY SPECIAL CONSIDERATIONS FOR HEAVY MACHINERY IS 3 feet, 0.91 meters.
On what basis are you proposing to put heavy machinery on 750 mm cover? You said it is for nondesignated locations, so I assume you will not case the pipe, or put a reinforced concrete spanning slab on top everywhere you expect to have a nondesignated crossing locations.
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek
RE: Heavy Machinery loads on pipelines
3feet is the minimum cover if you design to B31.8.
Australian Standards allow 750mm depth of cover. If infrequent crossing of heavy machinery, farming machinery, etc. does not cause any problem for the pipeline there is no reason to have 900mm DoC.
RE: Heavy Machinery loads on pipelines
So, if you are already under 1102 recommended cover, you must be pleanty close to the limit then, right. If you guys start using "heavy" farm equipment some day, that sounds like trouble. The reason API 1102 doesn't cover those shallow clearances is that 3 ft is the absolute minimum and 4 feet is the customary US depth for normal weight farm equipment passages, due to usual maximum depths of root plow penetration, and for unpaved track crossings. Yes, we bury the pipe at 4 feet cover in farmland. I and 1102 are telling you 750 mm isn't safe for what I/we would consider as "heavy farm equipment", no matter what is, or isn't, allowed under Oz standards.
Do Oz standards allow heavy farm equipment passing on 750 mm cover, or is that really just the minimum clearance allowed, to which you must add extra depth when it is expected that "heavy" farm machinery will cross? Read your Oz code with a more critical eye and see if your opinion is still the same.
I'm afraid that with 750 mm cover, in a farm area where heavy equipment is active, I would want to fence off the RoW completely.
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek
RE: Heavy Machinery loads on pipelines
RE: Heavy Machinery loads on pipelines
What magnitude of load is considered "heavy" farm equipment in AU?
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek
RE: Heavy Machinery loads on pipelines
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek
RE: Heavy Machinery loads on pipelines
Bury a 20-ft joint of pipe with exactly 750mm of cover on one end, rising to 600mm of cover on the other.
Then run a Chisle plow across the pipe, set to dig deep. You should dig up and/or scar the shallow end, might scar the 'deep' end. Think about tolerances in the "Real World". If you specify 750mm, anticipate getting 600-900mm of cover in places. If you specify 900mm, you should never end up with less than 750mm of cover. Digging ditches is not like machining parts -- the tolerance zone is pretty wide.
RE: Heavy Machinery loads on pipelines
"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek
RE: Heavy Machinery loads on pipelines
RE: Heavy Machinery loads on pipelines
RE: Heavy Machinery loads on pipelines
Ibrahim Demir
RE: Heavy Machinery loads on pipelines
RE: Heavy Machinery loads on pipelines
This standard cannot be used for steel pipes.
RE: Heavy Machinery loads on pipelines
Regards,
Ibrahim Demir
RE: Heavy Machinery loads on pipelines
Structural Mechanics of Buried pipelines by Watkins
Two very good books on the subject.
“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King
http://waterhammer.hopout.com.au/
RE: Heavy Machinery loads on pipelines
I believe it is appropriate for steel pipelines as they are flexible in diameters that you refer. In fact ductile iron pipe is also referenced in the standard. The criteria assessed are strain, stress , buckling, deflection and combined loading. The standard is quite conservative particularly in the use of native soil modulus. The concept follows that of Spangler Iowa, ATV etc.
Rigorous assessment using this standard will render you a design. The native soil will carry most of the load when the steel pipe deflects. Hence you need to assess the properties of the native soil, design an embedment to suit and make sure it is installed correctly.
If you are concerned about fatigue with a large number of cycles then you will need to establish the number. Does it apply to the whole pipeline or just for tracks and road crossings? If so then perhaps a pavement is required for crossings.
Even at 750mm deep the trapezoidal spread of wheeled loads will reduce the pressure at the pipe considerably.
“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King
http://waterhammer.hopout.com.au/