Aerial Crossing of Natural Gas Pipeline
Aerial Crossing of Natural Gas Pipeline
(OP)
What forces must be considered when attaching a pipeline to an existing bridge? How do you mitigate thermal expansion of the pipe? Are thrust forces a factor? The span is 1200' long. Any help is appreciated.
Thanks
Thanks





RE: Aerial Crossing of Natural Gas Pipeline
Alternately, expansion loops could be added, if space is available.
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Aerial Crossing of Natural Gas Pipeline
If there are differences in temperature, there will be differences in the expansion/contraction rate and you will have to account for those, either by allowing the movement in a controlled manner without affecting the stability of the pipe or by restraining the pipe enought o account for the strain generated by the thermal expansion.
RE: Aerial Crossing of Natural Gas Pipeline
I assumed (maybe incorrectly) that you were talking about a steel pipe. If it is steel, what I said is correct. If it is PVC or other material, the rate of expansion/contraction does not necessarily have to be the same as that of the bridge structure.
RE: Aerial Crossing of Natural Gas Pipeline
Ftot = Fp + Fs + Ff + Fc
Where:
Fp = p * A
Thrust due to inside pressure (p = pressure in N/m2 and A = transverse area of the expansion joint bellow in m2)
Fs = K*dL
Spring force of the bellows (K = spring constant of the bellow in N/m and dL = length variation due to thermal expansion in m)
Fa = F*M
Friction force (F = friction factor and M total weight of the pipeline between anchors)
Fc = (2*At*w * v^2)*sin (ang/2)
Centrifugal force (At = transverse area of the pipe in m2, w = specific weight of the fluid inside the pipe in kg/m3, v = fluid velocity in m/s and ang = angle of the pipe).
Usually the last term Fc has to be taken into account for high pipe diameter and fluid with an high specific weight.
RE: Aerial Crossing of Natural Gas Pipeline
NO EXPANSION JOINTS SHOULD BE USED HERE!
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Aerial Crossing of Natural Gas Pipeline
1) Dead Loads, weight of the pipe acting on supports
2) Dynamic Loads, any vibratory excitations from the bridge structure (may be quite nasty for a bridge) or pulsations in you gas flow causing shaking of the pipe (not likely).
3) Thermal growth loads, Loads imparted to the structure from the thermal growths of the pipe. These growths are calculated from the temperature of the fluid in the pipe and the thermal growth properties of your pipe material. Follow BigInche's advice on the control of thermal expansions. These expansions will also produce thrust loads on your intermediate supports due to the normal force from dead loads multiplied by the appropriate friction factor (0.4 for steel on steel) for your pipe and support materials. This must be taken into account for all sliding supports.
4) Wind Loads, load on the supports due to wind on the pipes cross sectional area, likely to be significant for a bridge with the pipe exposed
.
5) Earthquake loads, Dead load accelerated in the lateral directions by earthquake, size in accordance with you local requirements.
Just my two cents worth.
Always remember, free advice is worth exactly what you pay for it!
RE: Aerial Crossing of Natural Gas Pipeline
RE: Aerial Crossing of Natural Gas Pipeline
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Aerial Crossing of Natural Gas Pipeline
RE: Aerial Crossing of Natural Gas Pipeline
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Aerial Crossing of Natural Gas Pipeline
What are the "cons" of using expansion joints when dealing with steel pipes instead of ductile iron pipes?
RE: Aerial Crossing of Natural Gas Pipeline
Maintenance, maintenance, maintenance, maintenance. Did I mention maintenance (in an often far away location)?
Not to mention the typically higher pressure, leaks, with the added potential of endangering the public by a flamable gas being released into an area with no lack of ignition sources.
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Aerial Crossing of Natural Gas Pipeline
All it will take is a minor change to the support during maintance 5 years from now by a road crew who never should have touch it and BAM, blown bellows.
I avoid a bellows unless its absolutly needed, usually only due to a lack of arrangment space to get the needed flexibility or extremely tight pressure drop requirements.
Always remember, free advice is worth exactly what you pay for it!
RE: Aerial Crossing of Natural Gas Pipeline
Thanks for your explanation: a good display of skills and competence.
RE: Aerial Crossing of Natural Gas Pipeline
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Aerial Crossing of Natural Gas Pipeline
rmw
RE: Aerial Crossing of Natural Gas Pipeline
http
Thread header was in the pumps forum, "DissolvedGasAndCavitation"
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Aerial Crossing of Natural Gas Pipeline
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Aerial Crossing of Natural Gas Pipeline
RE: Aerial Crossing of Natural Gas Pipeline
Keith Cress
kcress - http://www.flaminsystems.com
RE: Aerial Crossing of Natural Gas Pipeline
While it is true that thermal loads are routinely considered, I have designed some pipe restraints in nuclear facilities for whip loads from pipe breaks, but never have I done that for refinery, pipeline stations, or offshore platforms, except at specific blowdown and relief valve locations. Some specific pipe supports or underground "thrust blocks" may be installed and designed for loads due to change-of-direction of fluid flow thrusts at elbows, tees and blowdown points where the pipe itself may not carry those loads, but for outright pipe breaks, I can't say its typical practice.
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Aerial Crossing of Natural Gas Pipeline
Also, about the only other thing I would add seeing others responses already to this thread is that under the heading "Combustable Fluids" (not my spelling, but you can tell Engineers did it!) MOP #89 says, "A casing extending the length of the bridge and a sufficient distance beyond is usually recommended." While not purporting to know all the reasons for such casing (or in effect double pipe) recommendation, I would think it could be argued that casings might reduce the vulnerability or increase the security of such crossings in perhaps multiple respects.
RE: Aerial Crossing of Natural Gas Pipeline
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Aerial Crossing of Natural Gas Pipeline
RE: Aerial Crossing of Natural Gas Pipeline
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Aerial Crossing of Natural Gas Pipeline
RE: Aerial Crossing of Natural Gas Pipeline
RE: Aerial Crossing of Natural Gas Pipeline