Is it safe and reliable operation to mix 3-phase production stream gathered from a certain offshore oil platform and planned to be connected down stram a pump that discharges liquid stream (oil and formation water)to an onshore separtor? Keeping in mind that pump discharge pressure is greater...
GDD
Thanks alot for your long breath discussion and valuable comments that i would highly appreciate.
I would ask about your advice regarding such below issues.
Till we, based on an organisational scale investigation, catch the most likely failure root cause and although this is a hard mission...
Come back,
We have informed recently via verbal confirmations, that many times when instrumentation guys do their routine PM at the production platform, they reported verbally a non conformance events, they found the level control loop of the production separator upstream the pipeline routinely...
Conversely, another important information that disrupt my guess in fatigue failure is that the diver points in a diving vedio to a confirmed hole beside one of the ruptures with dimensions of 2.5 cm length in 1 cm width!
Video is attached; the hole is clearly seen at the second 71 (01 minute:11...
The 4 O'Clock rupture is the nearest one to shore line so nearly it has the highest elevation (-11 m)relative to the upstream remaining three ruptures as the line runs from -40 @ riser seabed-touchpoint to the downstream onshore terminal of a relatively sea level elevation.
Another issue that...
In the above main thread, I did mention the below status:
On the other hand, few months ago, the onshore section connected to this subsea pipeline has suffered a lateral movement of about 1.5 meter over the resting concrete supports that caused damage observed for the old pig trap supports...
@Steve
The TWI study target the normalized residual stress readings (residual/yield - Y axis) versus a specific location relative to the sample thickness (normalized thickness-X axis).
This is different issue that I would present.
In metallurgy science,the below is a rule:
Increasing the carbon...
@GDD
The line pipe spec. as requested by the Engineering company was PLS2.
Iam trying to find the MTR of the purchased line pipe received from steel mill.
Note:
In the attachment, the bottom green mark/arrow refer to No Sour as supplementary requirements of the line pipe specification sheet...
@ GDD
One thing I am wondering is why the cracks are all at 0 O'Clock position.
No. I didn't mention that, refer to the main thread, I mentioned the same O'Clock not 0 o'Clock position.
Anyway, the divers vedios reported the 6 O'Clock position; definitely, three locations at 6 O'Clock and the...
@ weldstan (material)
Firstly, thanks for your comment.
I think you get broaden the uncertainty domain of the parameters relevant to this pipeline failure case.
But, as stated in your audit results which concludes that a major percentage of the mill produced pipes for defined steel grades are...
@Mr. Steve
I have quickly browsed the relevant technical paper you have recently attended but shurely, it needs much time to study and well recognize it's invaluable content.
Really it focuses on a critical parameter (residual stress effects) that should be profoundly considered and controlled...
@GDD
Thanks alot 👍 for your thorough engineering comments.
I did suppose that the pipeline design had referencd NACE compliance as all site precess offshore and onshore pressure vessels were actually designed to comply with NACE requirements for sour service.
But, now, I don't suppose that...
@Mr. Steve
Thanks for attaching such relevant and important technical paper.
I will read it soon to pick such relevant issues.
Again, highly appreciate your cooperation.
@SJones
The effect of HAZ residual stress would promote cracking when welding conditions support this.
But our case, we have mild steel grade X52 of very low carbon content and small wall thickness of 9.5 mm sch.40 pipes at all leakage/rupture locations. Those with accompanied qualified WPS...
Also, here's the pipeline general data.https://files.engineering.com/getfile.aspx?folder=7f5fc453-bd28-4b75-a957-f67017081c84&file=New_12_inch_crude_oil_transmission_line.pptx
Here is the general characteristics of the crude oil analysis.https://files.engineering.com/getfile.aspx?folder=93e423c5-036a-4977-9a59-f1571730c17e&file=RB-Generalcaractaristic_crude_oil_Analysis.pdf
Reply to Mr. SJones (Petroleum):
Did the "corrosion inhibitor management" include assessment of the propensity for the inhibitor to cause preferential weld corrosion? The weld metal composition is also an interlinked parameter.
-At the beginning, i got suspect in the selective girth weld...
Reply to Mr. blacksmith37 (Materials):
Depending on total pressure , 200 ppm H2S can cause sulfide SCC of hard weld HAZ; that would be the first place I looked.
-From this point of view, I wouldn't think in the HAZ SCC, as the pipeline operating pressure doesn't exceed the 6 or 7 bar of the 40...
Reply to Mr. LittleInch (petroleum):
Also: If you get a response it's polite to respond to it.
- Here I present my apology to all esteemed participants repeating my previous status:
Execuse me, every one, nearly all times I login, the website, i get server error/access denied.
Thanks for all...
Reply to Mr. Black Smith 37 (material) and 1503-44 (Petroleum).
The produced crude is not sour one, the H2S content doesn't exceed 200ppm.
On the other hand the pipeline design specs had referencd the NACE 0175 for any future sour service operation.
