Pipeline Welding Techniques

[thandion]

Good morning,

I am working with piping company which specialized on only aboveground pipeworks. And there is an upcoming pipeline work that we will possible get awarded.

Our old procedures are outdated, could anyone explain me current pipeline works. I mean is 2-3 group stick SMAW welding still popular?

Should we do Argon GTAW root and then SMAW fill? Work is roughly 100km, will full SMAW be faster? Or is it not worth it due to the better root result with GTAW root.

Thanks,

 

[denlow60]

Hoi thandion's ,

what is the thickness of the pipe ?

Denlow

 

[thandion]

denlow60,
Pipe is 20 inch probably standard sch. 9.53mm. X60 material.
Regards,

 

[denlow60]

thandion's

GTAW root and then SMAW fill like good to my.
group 2-3 stick SMAW is cool.

But I don't now how other gay's think about this matter.

Denlow

 

[weldstan]

Assuming you have competent pipeline welders, EX010 will be considrably more economical than a GTAW root.

 

[denlow60]

weldstan,

X60 have a Yield strength of 415 MPa ,EX010 have a Yield strength of 330 MPa Howe you want to fix this?

 

[weldstan]

denlow60,
There are many grades of EX010; e.g.,E7010-G, E7010-A1, E8010-G, E9010-G. Not just E6010.

 

[wegm]

thandion,
It's true that GTAW gives good root but if you prefer higher productivity you can switch to GMAW-STT that is a type of GMAW process with which root can be effectively welded. Please have a look at this link: GMAW-STT (Surface Tension Transfer) for CS
regards,
wegm

 

[denlow60]

hello Weldstan,

denlow60,
There are many grades of EX010; e.g.,E7010-G, E7010-A1, E8010-G, E9010-G. Not just E6010.

thandion ask for sticks in group 2 or 3 , but only E9010 are in this list and it have a yield strength of 530 Mpa and this is to much

regards,
Denlow

 

[weldstan]

E8010 is in Group 2 as well. Understand that E7010-G has been commonly used to weld X60 pipe for decades. All weld metal tests in the as welded condition have repeatedly exhibited Y.S. > 60 ksi.

 

[denlow60]

Weldstan,

Yes you are right about E8010 this is good for X60.

but for the ISO standard is this really so but ASME 2013 SECTION II, PART C talk about this( E7010-G Yield strength ksi 57 / Mpa 390 and Tensile strength ksi 70 / Mpa 490 ).

regards,
Denlow

 

[DekDee]

Denlow,
You keep quoting yield and tensile strengths from ASME II (SFA 5.1 & 5.5) but these are not relevant to the discussion - they only show minimum required yields and tensiles for the manufacture of the electrodes.
Firstly - you do not have to match mechanical properties of filler metal to base metal for every application.
Some applications require matching, some require over-matching and some even require under-matching.

Secondly, as weldstan has noted E7010-G has been used for years to weld X-60 pipe.
Have a look at Lincoln Electrics web-site, probably the largest supplier of cellulosic electrodes in the world.
Lincoln states E7010-G may be used for X-60 and X-65 pipe.

Regards,
DD

 

[denlow60]

DekDee,
I'm coming back to you findings in a few days.


A7.1.8 EXX10-P1 (Pipeline) Electrodes. These
electrodes have been designed primarily for welding typical
high-strength pipe butt joints in the vertical welding
position with downward or upward progression. With their
cellulosic coverings, they produce deep penetrating, spraytype
welding arcs and thin, easily removable slag. This
combination is best suited for achieving full penetration
and radiographic quality for the downhill welding of butt
joints when the axis of the pipe is in the horizontal position.
While weld metals produced from these electrodes do
not have any minimum chemical composition requirements,
the supplier must provide sufficient alloying elements to
meet the increased mechanical property requirements. Special
emphasis must be placed upon the minimum yield
strength values, since most transmission pipeline materials
and systems are designed to yield strength limits. Typical
application for E7010-P1 [E4910-P1], E8010-P1 [E5510-
P1], and E9010-P1 [E6210-P1] electrodes is the welding
of API-5L-X52, API-5L-X65, and API-5L-X70 piping
assemblies, respectively.

Regards,
Denlow

 

[DekDee]

Denlow,
Try this hypothetical.
I take two pieces of API 5L X60.
I weld them together with E6010.
I perform all the mechanical tests required by API 1104 and they all pass.

Do I have an API 1104 qualified Welding Procedure or not ?
Regards,
DD

 

[denlow60]

DekDee,

Welding aspects :
Weld metal yield strength equal to yield strength base material
Strength weld is determined by strength in weld metal
1.design strength is determined by the base material

EXX10 excess hydrogen electrode has therefore has no preference.
Low hydrogen electrode with a < 5 ml have preference. Hydrogen from the material and filler material shall be minimum
With high strength material, be careful for crack in HBZ zone .

with second -generation high strength material : if you weld de root you have to use about 100 MPa, less than the parent material

Regards,
Denlow