Welding - NACE

[Deepray]

Hi,

Does anyone know about welding to be qualify as NACE?

Recently i was told by someone that the old water pipeline my company designed is not suitable to be converted to Oil pipeline as the weld on the water pipeline offshore is not NACE. I have checked in many industrial code and have yet to find something regarding this.

Can any expert here enlighten me a bit on this theory; whether is it correct and where i can find the relevant write-up or requirement on this?

 

[EngineerTex]

You would want to consult NACE spec MR-1075.

The long and the short of it is that water pipelines rarely have to deal with hydrogen sulfide while it is often a component of crude oil.

On the other hand, the NACE spec directs the customer to supply the designer/engineer/fabricator with the chemical composition of the fluids in order for the designer to select the appropriate metallurgical makeup of the pipeline as well as the weld.

After you determine what is needed for the weld, then you can determine if the welds you have will meet the requirements.

Engineering is not the science behind building. It is the science behind not building.

 

[SJones]

If it is a carbon steel pipeline, the welds and HAZs will only have two criteria as per ISO 15156-2 (please note that I am quoting ISO because, at 2009, it is a more up to date version than the joint MR0175 which is only just out for acceptance vote):

Maximum hardness 22 HRC
Maximum nickel content < 1 mass%

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[PAN]

Deepray,

The old water pipeline might not be controlled at the same quality level of oil pipeline during construction...

At first, I suggest you to review the QA/QC dossier of existing water pipeline and inspect the present condition of this line before further process...

 

[GregLamberson]

Deepray,

Agree with PAN, you'll need to look at the as-builts and data books, pipe dia & wt, and do the calcs. A hydrotest would be in order plus an intelligent pig run to identify corrosion at a minimum. Valve suitable is another.

You mention offshore, I would be very hesitant to use an "old water pipeline" to carry oil offshore, seems like a huge liability potential. It would take allot of convincing to pursuade me that new was not the way to go.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[whammett]

I agree with GregLamberson. This is definately not an area where you would want to take shortcuts, especially not without extensive testing.

"I came, I saw, I made it better."
-Ode to Industrial Engineers
Will ChevronTexaco Corp.

 

[Deepray]

Its a new water injection pipeline that the Client are looking at converting it to oil line.

From Design point of view, as long as the pressure and temperature is acceptable then it is fine. Not sure from material point of view. This is why the qns is rised.

 

[JRMacGregor]

Deepray

I think EngineerTex has given you good advice

NACE is commonly specified if the system has to handle H2S

If your petroleum engineers can guarantee no H2S then you may be able to ignore this NACE standard and use your pipe.

You are on the right tracks - NACE is a MATERIAL issue - pressure and temperature etc are separate.

You are right to question your colleague who implies that all hydrocarbon lines have to be NACE.

Crude oil tankers (ships) carry crude oil and they dont normally need NACE specs. Admittedly that is not exactly the same as the crude oil in the well stream, but you get my drift.

 

[nhliew]

If you haven't constructed it, specify the materials, welding, NDE and stress relief to comply to NACE requirements.

If you have, take the materials, welding, NDE and strees relief records and compare with NACE requirements. If in the process of construction some requirement is not accounted for, don't try your luck.