Pipelines pressure tes - To be or not to be
Pipelines pressure tes - To be or not to be
(OP)
Dear mates,
In some oil fields, vandalization of flowlines is very common, some times is the first cause of leaking, spillage, etc., more than corrosion.
The question come out when repair or sectional replacements, with new and duly certified piping, are to be done, after the welding job is completed the criteria some times is about "golden welds", but when the quantity replaced is bigger, normally hydrotest of the complete lenght of the line should be requested.
But, is right to perform this test when the line was previously in operation and even sometimes its integrity condition is not well known.
So, this is te question, thanks in advance for any input you can have.
In some oil fields, vandalization of flowlines is very common, some times is the first cause of leaking, spillage, etc., more than corrosion.
The question come out when repair or sectional replacements, with new and duly certified piping, are to be done, after the welding job is completed the criteria some times is about "golden welds", but when the quantity replaced is bigger, normally hydrotest of the complete lenght of the line should be requested.
But, is right to perform this test when the line was previously in operation and even sometimes its integrity condition is not well known.
So, this is te question, thanks in advance for any input you can have.





RE: Pipelines pressure tes - To be or not to be
An alternative is to strength test the new section (1.5 X dp or whatever code you use) and then leak test the whole line while you can to Design Pressure or 1.1 x DP to prove the entire section.
If you have concerns about integrity then you should deal with this separately, not as part of a replacement section pressure / leak test. An operating company I used to work for did an annual leak test to Design pressure in product as a way of "proving" integrity in the days before intelligent pigs becam small enough to run in lines < 16", but that is not normally undertaken now. Pressure testing in water is a way of proving integrity at the time of the test, but can weaken pipelines if a small secion has corroded and is plastically deformed, but not enough to rupture.
Only you can determine whether the relative risks and knowledge of the pipeline justify the time and expense of a complete pressure test or not.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Pipelines pressure tes - To be or not to be
RE: Pipelines pressure tes - To be or not to be
Independent events are seldomly independent.
RE: Pipelines pressure tes - To be or not to be
RE: Pipelines pressure tes - To be or not to be
MJCronin - sorry but can you explain what we're supposed to be in denial about?
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Pipelines pressure tes - To be or not to be
My question should be, why to penalize the entire lenght of the flowline, which was in operation before, by making a pressure test, when just a portion of it was replaced by duly certified pipes and the welds joints released as a golden welds.
RE: Pipelines pressure tes - To be or not to be
You were the one who made the comment regarding hydrotesting the whole line and you also noted the integrity may be unknown.
Are you the contractor or the owner of this pipeline ?
If you are the contractor you are probably not concerned with the integrity of the remainder of the pipeline.
If you are the owner of the pipeline you should most certainly be concerned with the integrity.
Both Big Inch and Little Inch make valid points.
As far as I am aware there is no code requirement anywhere that states you must test the complete line if you replace 1, 10 or 100 lengths of pipe.
Perform NDT on all welds, hydrotest the replacement section or sections,remove the end caps, install the section or sections, NDT the two golden welds and then place the line back in service.
As Little Inch noted, Pressure testing the whole line to DP with product to determine integrity is one way of doing it but as also mentioned smart pigs now make that practice pretty much redundant.
Cheers,
Dek Dee
RE: Pipelines pressure tes - To be or not to be
Independent events are seldomly independent.
RE: Pipelines pressure tes - To be or not to be
RE: Pipelines pressure tes - To be or not to be
"But, is right to perform this test when the line was previously in operation and even sometimes its integrity condition is not well known." Is it "right"? It is not right or wrong. Pipeline companies make "maintenance" hydrotests all the time as a way to verify the integrity of the line, at that moment, ususally when other options are not avaialable, or to get it operating again after a failure, etc. So yes, operators are hydrotesting lines previously in operation all the time. Hydrotests are not just for commissioning new pipe.
If you don't want to hydrotest the entire line, I don't see what the issue is with hydrotesting the spools prior to installation and then completing full NDT of the golden welds? You may not have to hydrotest, assuming the regulations where you are would be similar to others.
I don't understand how you would be "penalizing" the line, my opinion is that you would not be "penalizing" the rest of the flowline, but helping it. If this scenario came up for me, I would welcome a hydrotest when the integrity condition of the line is unknown. It would demonstrate at least the line can hold a certain pressure today, which is more information than you had before. You can also use the pressure test data to back calculate the size of a remaining anomaly etc. and use this information to help with the integrity assessment moving forward. I don't know why you would want to risk having a product failure as opposed to a hydrotest failure? It is a lot easier to deal with a hydrotest failure from a regualroty perspective than a product failure, at least you can say you were completing some due diligence on the line, whereas before it was a case of neglect.