Operating a pipe above the design pressure

[hniaboujemaa]

Hi guys,
Given that the pipe has been tested @ 1.5xDP, what will be the impact on operating this pipe above the Design pressure..

Thanks

 

[chicopee]

Not advisable.

 

[augern]

Some piping codes (B31.1, B31.3) allow occasional operation above design pressure given certain conditions.

 

[MiketheEngineer]

Other than someone might die - no problem!!

 

[Chance17]

I copied this from a reference for ASME B31.3 (process pipe)
"Pressure of not more than 33% above the design pressure at the temperature of the increased condition is permitted
for a maximum of 10 hours at any one time and for less than 100 hours per year,
provided the restrictions in Par. 11.3.4 are met."
To comply with B31.3 you also need a means to measure and document overpressure occurrences.
The main impact of operating above a pipe's design pressure is administrative i.e. are you following acceptable Industry standards. If not, some legal issues may be triggered.
There is no legal exposure operating below the design pressure if the pipe is designed to Code.
It is gross negligence to operate above the hydrotest pressure.

 

[C2it]

Operating at +33% above design prssure means that the hoop stress in the pipe may be at specified yield stress, thus no margins left for any unforseen problems. Not illegal but beware.

 

[Eddycurrentguy]

Not withstanding the above comments, the pipe may have passed a 1.5 hydrotest at some time, but the capability to withstand that pressure now may not be possible under current conditions--pressure cycling, frost thaw/heave, SCC, corrosion, etc....

 

[racookpe1978]

What project? What plant? What state?

(I need to make sure my schedule avoids the place.)

 

[hniaboujemaa]

Thanks guys for your valuable information.

 

[cvg]

the impact is a higher probability of failure. What is the consequence of that failure? Persons at risk? Life safety? Property damage? Environmental contamination? What does the insurance company think about your decision to do something risky?

 

[TGS4]

Where are you located? If you are in a jurisdiction that makes the ASME B31.3 Code the law, then exceeding the provisions that Chance17 and others have stated above is ILLEGAL, and doing so could find you in a heap of trouble.

 

[MJCronin]

What has not yet been mentioned above is flange leakage.

If you have a flammable. cumbustable or toxic liquid and you operate above the design pressure, the lawyers may come to knock on your door.

Flanges commonly (but not always)leak before piping fails....