Piping Overpressure
Piping Overpressure
(OP)
Does anyone know what the guidelines are for piping ruptures i.e., at what pressure will piping rupture without a blocked flow condition (fluid with a open flow path to a low pressure rated vessel). I'm looking for a good resource on this subject. For example: 2000 psig gas flowing through 250 psig rated piping into a 250 design pressure vessel.





RE: Piping Overpressure
When the downstream outlet pressure plus the pressure drop of the flow through all the equipment is greater than or equal to the lowest burst pressure of any piece of equipment, you've found your maximum flowrate.... the hard way.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Piping Overpressure
I think the Crane TP 410 paper may discuss this.
RE: Piping Overpressure
In the pipe design pressure formula, there is a Basic Design Factor F that takes into account the intended use and location of the piping. This design factor varies from 20% to 60% pressure derating. You have not provided enough information to get into any more detail.
RE: Piping Overpressure
bimr, "F" =1 when investigating yield hoop stress and "F" = ultimate_tensile_stress/yield, when investigating rupture hoop stress.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Piping Overpressure
MAWP = Maxmum allowable working pressure. (ie design P)
P = 1* MAWP to 2* MAWP < Low probability of failure
P = 2* MAWP to 3* MAWP < Probable failure (0.5 chance)
P = 3 * MAWP > Near certain failure.
depending on the code you can replace the 3 with the 4.
Unless the pipe is overdesigned DONT SEND 2000 psig gas down the line YOU WILL FAIL THE LINE AND VESSEL
RE: Piping Overpressure
I know we've gotten pretty far off track from the initial question, but that question was quite confusing. What is the relevance of a connection to a low pressure vessel? Why specify that the outlet is not blocked? You may not get the responses you want because the presentation does not make sense.
Does that make any sense?
Doug
RE: Piping Overpressure
But if he's trying to figure safety factor or something, that's legal engineering work. Wether he works for the US Army or Al Qaeda is not my business.
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Piping Overpressure
We will leave the risk lawyers to sort out probability of failure and how much to pay orphans.
RE: Piping Overpressure
Pressure is driving force. As Pressure decreases, gas expands and velocity increases. Temperature can increase or decrease depending upon relative effect of gas expansion and friction.
Rupture will occur at a fixed sonic velocity (the critical value) with mass flow influenced by the upstream pressure. Sonic velocity is approximately 1400 plus ft/sec.
RE: Piping Overpressure
There are three commonly used formulas for calculating the burst pressure of seamless piping and tubing, Barlow’s formula, Boardman’s formula and Lame’s formula. Each uses the ultimate tensile strength of the material, at test temperature.
The formula that is incorporated into ASTM destructive test of piping is the Barlow formula, and is mentioned in the piping handbook.
Now, you should be aware that there are a lot of unknowns in burst testing of piping. Small defects and occlusions on the OD can affect the results. Variations in material properties and "out-of-roundness" can have an affect....
Testing of the same sample of piping will vary. Same with several other parameters.
The power piping code, ASME B31.1 allows a short time overpressurization of 20% if it occurs less than 1% ( as i recall) of the operating life.
Good luck..
-MJC
RE: Piping Overpressure
I don't understand your reasoning. Souldn't rupture occur at point where a specific pressure differential (inside to outside) occurs?
Also flow is not limited by sonic velocity for steady state gaseous flow. For isothermal flow (steady state)of a perfect gas the limiting Mach no = 1/sqrt(gamma) where gamma is the ration of Cp/Cv.
Regards
RE: Piping Overpressure
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: Piping Overpressure
BigInch - Not to make too many waves but got a chuckle out of your statement, "Wether he works for the US Army or Al Qaeda is not my business."
There is some wonderful satire on this. Tom Lehrers' song on "Wernher Von Braun". Very funny.. Wernher von braun makes the point that, "Where the rockets come down... thats not my department.. says Wenher Von Braun.".
RE: Piping Overpressure
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com