LEAKS ON NEW INSTALLED PIPE : API 5L GRB PSL1 and or 2 5

[Alaa1992]

Hy guys,

Any one can help me in figuring-out reasons on leaks, happened suddenly on a newly installed 6'' and 3'' process piping.

How can this happens fastly?
Has any body faced such a problem ?

DATA:
Time between commissionning and leaks occuring = 4 mounths ONLY !!!! Not years !!!!!! it is a couple of mounths !!!!!!!!
Liquid: Salty produced water
Station: Primary petroleum processing facility
Materials: API 5L GRB PSL1 and PSL 2 pipes, SCH40, Certified europeean standards and norms.
Hydraulic test pressure in field after installation: 16 bars for 2hrs ==> Test was OK

PS: I have verified all inspection reports; All parameters such as chemical compositions, yield strenth, mill hydraulic test are submitted within the standardized ranges, and our suppliers are with a good reputation in europe. (not chineese products)

Alaa Edine SMAALI
Energy (Oil&Gas) Project Engineer

 

[mk3223]

The thing happens for a reason. And you need to find out the real why(s).

It's not clear form your post, such as where the leak, how the leak looks like, the operation conditions, any process upset during operation, etc. It could be helpful to see some photos.

 

[weldstan]

"salty produced water" What temperature? What else is in the water? Did the pipe have some corrosion pits which accelerated corrosion in service? You do need to cut a section containing the leaks to perform a proper metallurgical evaluation. This could simply be the wrong material for the service.

 

[EdStainless]

Or biological attack, or any of about 6 other possibilities.
My favorite always is when there leave pipe wet after hydro and cause serious pitting. It then fails in service and everyone is surprised, when it reality it was already doomed.

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P.E. Metallurgy

 

[miningman]

Gasket details ??? Torque values ??? schedule rating ?? Theres a pile of missing detail here

 

[Alaa1992]

thanks gyus for your prompt answers,

I'm still searching for logical reasons by doing a re-verification of all inspection certificates done in the mill. i did'nt found something with a conflict.

Brief description:
the appearance of the first leak was near to a weld joint,so we thought at the beginning that damage might be issued from a bad radiography interpretation or a metal overheating during welding process . we verified the RT films but everything was acceptable.
I can provide you with a picture of this leak.(see attachement)

At this time, i knew that there is something wrong either with the metal itself or with construction work.
A second leak appeared on a straight pipe portion. and it was unfortunately after a couple a weeks (just yesterday).
I will upload the corresponding picture as soon as i can.

@mk3223 & weldstan: operation conditions: produced salty water @90°C. it's a recirculation 3'' line long approx 150m, related to a smal centrifugal pump discharge Pdis= 4 bars. Operators confirm to me that no process upset was happened. however there is a hight portion of H2S and some oil slugs due to the inificient seperation and we have considered this factor during pipe design and purchasing phasis (you know the compliance of pipe nuance with certain NACE requirements etc.. in addition that pipe was replaced on like-for-like basis: SMLS API 5L GRB PSL1)

@EdStainless: Wath other 6 possibilities ? i'm thinking about this and the corrosion pits, But how can this be so quick !!!???

Alaa Edine SMAALI
Energy (Oil&Gas) Project Engineer

 

[EdStainless]

What is the corrosion inhibitor that you use?
I would not expect carbon steel to stand up in 90C salt water, 100 days sounds about right.
Was the ID inspected? Ever?
How long between hydro and service?
What was the hydro water? Cl content? Biocide?

As to the like-for-like issue if the old material started in service with less severe conditions you may have formed a somewhat protective corrosion film, even though this isn't very reliable in CS.

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P.E. Metallurgy

 

[weldstan]

Agree with Ed especially if air (Oxygen) has been introduced.

 

[weldstan]

I would suggest doing some x-ray of the pipe to see how much pitting there is - general or isolated.

 

[EdStainless]

I'd start by grabbing a fiber scope and looking inside at some of the leaks and the nearby areas.
I bought a 5m long one that uses my phone as the viewer, and I have seen 10m long semi-rigid ones for less than $100USD.
Let us know what you find.
I never believe that above ground lines are oxygen free. Downhole yes, but once it at the surface you cannot realistically exclude all air, there will be leaks someplace.

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P.E. Metallurgy

 

[Alaa1992]

hy guys,

I have received photos about the 3'' pipe leak ocuured recently (see below)

@Edstainless:
I remember that there is no much time between hydro test, pipe dewatering and commissionning (couple of hours)!
No troubles were been detected during pressure mounting (especially with trapped air pockets) and it was performed with fresh water (with no harmful cl content). The ID/OD/WT of pipes were checked at mill with different instruments (this is mentionned at certifications) and i think that there is no remarkable metal loss. (PS: To detect any initial metal loss/manufuctering damage, i have compared the weight/length ratio during pipe reception with standarized values and it seems normal, I don't expect this is accurate, but it gave me an idea about a such possibility)

I reviewd your statement about the failure of carbon steel vs hot salty produced water during only 100 days and yes!
NORSOK M-DP-001 ''MATERIAL SELECTION'' claims clearely that The use of carbon steel (e.g A106 GRB, API5L GRB PSL1/PSL2) is very limited as long as fluid corrosion rate > 10mm devided by the design piping life.
Moreover,a table was given later describing material selection for topside facilities and it is recommended that produced water in Oil and gas production must be handled using one of the following steel grades: SS316, 22Cr duplex, 6Mo, Titanium or GRP.
In other words, if the Produced water at the facility nowadays is more corrosive, then the removed pipe nuance (API 5L GRB B, PSL1) can't be suitable anymore and can't resist!!

According to your experience, how far this can be a strong reason?
And if so (High corrosion rate), does it possible to happenned within a short period like this ? sorry I'm a little bit surprised but does a 100-days period enough to produce a failure like this (With the assumption that initial pipe state was pretty good)?

Alaa Edine SMAALI
Energy (Oil&Gas) Project Engineer

 

[Dhurjati Sen]

In one of your posts, you have mentioned H[sub]2[/sub]S.

You need to check the velocity of the fluid, as this H[sub]2[/sub]S or CO[sub]2[/sub] mixed water is highly erosive.

And surely the erosion could produce a leak within 100 days.

Carry out ultrasonic scanning around the leak and also the elbow to confirm erosion corrosion. The elbow, being thicker than the pipe, is yet to leak.

Best of luck.

DHURJATI SEN
Kolkata, India

 

[TugboatEng]

If this is welded pipe, both the butt welds and the seam, the weld tends to be less noble and will act as a sacrificial anode to the rest of the pipe. This could cause greatly accelerated corrosion at all welds.

 

[Alaa1992]

hy guys

DHURJATI SEN: I'm investigating different reasons, in particular fluid velocity, Many studies claimed that the faster the fluid is (with a huge amount of CO2 & Salinity), The greater its corrosion rate (which can reach 11mm per year). Additional pipe tests (chemical & mechanichal analysis) are in progress.

@TuboatENG: It is a Seamless pipe. Otherwise, How this can be possible. Across my experience, I didn't saw something similar before. (I'm talking about weld joints are acting as a sacrificail anodes). Is this has a relationship with a such metal non compliance with the fluid inside ?

Alaa Edine SMAALI
Energy (Oil&Gas) Project Engineer

 

[EdStainless]

TBE, and in some cases the welds act more noble and the HAZ gets eaten quickly.
Look inside and talk with your corrosion inhibitor people.

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P.E. Metallurgy

 

[Alaa1992]

Ed, you mean a wrong about the used corrosion inhibitor?

Alaa Edine SMAALI
Energy (Oil&Gas) Project Engineer

 

[EdStainless]

Wrong one, wrong balance between two that are used together, wrong amount, broken injection quill, there are lot of things that can go wrong.
You also need to really look into the cathodic protection system also.

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P.E. Metallurgy

 

[LittleInch]

Hang on a minute here.

This post is bouncing around all over the place.

First - What exactly is the fluid? Hot / warm salty fluid with CO2 and H2S in, especially if it has any level of Oxygen more than about 30 ppm, is incredibly corrosive to Carbon Steel.
Is there corrosion inhibitor injection?
Are there any linings?

The HAZ is often subject to corrosion more than the main pipe.

316 will pit so you're into Duplex or lined or nonmetals.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.