Hydro test pressure exeeds the set value
Hydro test pressure exeeds the set value
(OP)
10" Sch 120 pipe is hydrotested at 165.45Barg pressure. The relief valve was set of 1.1 times this pressure (181.99Barg). However during test the pressure went upto 188 Barg. due to improper settings.
Will this raise in pressure (188Barg) have any impact on properties of pipe material? Has any permanent deformation set in? How do I justify this?
Any help is of great benefit.
Thanks.
Will this raise in pressure (188Barg) have any impact on properties of pipe material? Has any permanent deformation set in? How do I justify this?
Any help is of great benefit.
Thanks.





RE: Hydro test pressure exeeds the set value
Do you have a plot of volume of water injected vs pressure? (And if not why not?) If you plot volume (x axis) vs pressure (y axis) and it's still a straight line then you should be OK. If it flattens off ( unlikely) then you've strained the pipe, but you would need to look at it carefully.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Hydro test pressure exeeds the set value
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
RE: Hydro test pressure exeeds the set value
Still need to see what the material and what your design pressure and temp is to confirm, but I think you've almost certainly got away with it so long as you're using Carbon Steel.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Hydro test pressure exeeds the set value
We checked the line list and found that the line is designed for 110 Barg pressure whereas the pipe class selected allows us to design for 138.8 Barg. This allows us to reach upto 208.2 Barg test pressure without bothering SMYS. A pressure of 188 Barg is well within this valve (208.2 Barg).
Thanks LittleInch for giving the idea of design pressure. Relieved to have gotten away with it without doing some complex analysis... :)
Shaff
RE: Hydro test pressure exeeds the set value
If so, you can up to 1.5 times the flange rating @ ambient Temp. without any problem for the hydro case. From your OP and replies, I cant make up if this is true.
138.8 bar(g) is a flange rating for a B16.5 grp 1.17 flange @ 200 C, and F12 Cl 2 or F5 are (low-alloy) carbon steels if Im not mistaken.
PS: carbon steel a MoC designation is too plain. Carbon steel comes in several specs (ASTM/EN) and a wide variety of grades. Be more specific next time.
RE: Hydro test pressure exeeds the set value
For instance, let's say I calculate for a CS pipe that I need for a 4" pipe a wall thickness of 5mm (based on standard tension calculation) and I add a corrosion allowance of 1,5mm to that. That brings me to 6,5mm. Schedule STD is 6mm, so I have to go up a level, which brings me to Schedule XS; 8,6mm. That gives you 2,1mm extra to play with. In you case you might have a similar situation.