For our main and cross country pipeline welding we are have qualified the WPS for API 5L X-60 to API 5L X-60 pipeline.
Now we have some canals where we are using Seamless pipe of API 5L X52 (12.7 mm) which will be welded with the main pipeline API 5L X-60 (6.4 mm).
I like to ask you that according to API 1104 Para 5.4.2.2 where it says “A change in base material constitutes an essential variable. When welding material of two separate material groups, the procedure for the higher strength group shall be used”.
Group A : SA 106 Gr. B, API 5L Gr. B, API 5L X-42
Group B : API 5L X-52, API 5L X-56, API 5L X-60
Group C : API 5L X-65
Can we use the same WPS qualified for API 5L X-60 on the combination of materials i.e. X-52 to X-60 as both materials lies in same material group (Group B) and we have qualified the procedure for the higher strength material per the code guidelines !
Very little is black and white in API 1104.
When in doubt, ask the engineering firm that has overall authority on the project.
Al
Yes, according to 5.4.2.2. as long as your PQR was made with the highest tensile material in the group (Group B API 5L X-60), and the other material is also in Group B (API 5L X-52), you may use the WPS (Assuming all other essential variables are covered)
There is a Note in 5.4.2.2 that states that metallurgical and mechanical properties need to be considered IF you pre and post heat treat.
Can we use E 7018 on the same joints (Second question)
Some opinions are that E 7018 have good resistance to under bead cracks. If it is true for higher strengths pipes then why we shouldn't used E 7018 instead of earlier qualified E 8010 P1 (Pipeline Electrode)
Sorry this response is a little late. Cellulosic electrodes (EXX10's) are very common when welding the mid-high yield strength groups up to and including API 5L - X70. What you mention has merit. Due to the nature of the high production rates associated with these electrodes and the common skill sets of the various locals/contractors performing these welds E8010 is used quite frequently.Typically when addressing these concerns (hydrogen cracking for example) when using EXX10 electrodes a strict preheat and inter-pass maintenance is utilized, usually around 225 degrees F minimum. Upon completion of welding a 'hydrogen bake-out' process is applied. The weld zone temp is either reheated or verified that it is still approximately above the minimum preheat temp and held for a specified duration to allow hydrogen diffusion, often wrapped to slow the cooling rate. Not addressing concerns like the one you have mentioned when using EXX10's on API 5L-X52 and up materials, especially when welding on older pre-1970 pipelines, would be irresponsible. Specific information regarding issues like this one can be found at the Pipeline Research Council International (PRCI)...
Also, to use E7018 would require procedure qualification. These can not be substituted for E8010's per qualification variables in 5.4.2.6 and table 1.
The ability to weld a open root 7018 is an uncommon skill. Not a skill used or learned by pipeline welders. And not a process that is conducive to rapid production. Cracking of DH welds and other bead defugilties is easy to control by close monitoring of pre-heat and proper weld disposition rates. Using minimal grinding of the root and holding the clamps until the bead is fully welded and the pipe is set on the skids.
Some are under the impression a 7018 weld is a "better weld". A poor 7018 weld is not better than a XX10 weld simply because it is LH. And I have personal experience of 99-100% fail rates on welders testing on the open root 7018. Most welders who run 7018 day in and out cannot do it, And when you are trying to do it on say 0.375 wt, pipe, well lets just say, it is not going to be pretty.
Cross country pipeline have proven for many years the DH XX10 rods make sound welds.
This is a training issue - root passes with EXX18, 15, 16 low hydrogen electrodes. I'm actually re-qualifying 30 U.A welders this week on open root utilizing E7016-H4. True, EXX10's have been used successfully but also have contributed to failure. Pre-heat and inter-pass temp control in certain conditions and on certain materials is strongly recommended by the electrode manufacturers and by regulators. US D.O.T. (PHMSA) strongly recommends the use of low hydrogen processes/electrodes on higher yield materials. If cellulosic electrodes must be used then corrective actions preventing hydrogen assisted cracking should be utilized, including adequate delay times for NDT and 'time at temperature' or 'hydrogen bake-out' methods to allow for hydrogen diffusion. A couple references regarding this issue (posted here before):
https://primis.phmsa.dot.gov/construction/docs/ConstructionIssues.pdfhttp://ntl.bts.gov/lib/44000/44200/44214/44214.pdf
A training issue to say the least. Fit up is CRITICAL and UHOR bead on standard wall pipe in a production situation is something I would sell tickets to. ORLH bead calls for a welder who understands the relationship between the gap and the land. A fitter has to be trained just like the welder unless you are in a situation where the welder is responsible for the fit up. In that case, you are not talking about a XCountry pipeline.
I have tested over 300 welders in ORLH bead and of the first time welders 100% busted. And of the ones I kept up with or came back to test again over 50% failed the second time. This is the old Philips/DCP test using 2'' and 8'' sch 80. Now you may have a better pool of welders to draw from and it has been a few years since I was doing this, but that is a hard test. And very mental. You are using the right rod for the root instead of 7018, but you have to be sure when the welders are doing work they have the 7016-H4 available.
But hey, its just a training issue.
Correct, not a skill that one will just come in and test for. We worked with the locals for about 5 years before the requirements were implemented to give them ample time to practice and update their training curriculum. Not required by us while stringing pipe with contractors. In these situation preheat/inter-pass temp control is required per the approved WPS's. We do however use low hydrogen when installing new mains with company employed welders. Required of all for in-service welding and certain types of weld repair. Engineering call for high yield fittings/flanges/valves, heavy wall tie-ins in/around compressor stations. All contractors doing this type of work are required to maintain a supply of E7016-H4 including storage and handling requirements established in job specifications, OQ program and O&M manual. Adequate training takes time and effort to develop and implement.
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