crack in flange during welding

[jamNauman]

during welding of the following flange with A106 pipe, crack produces on flange with E/6010/7010 electrode, why?
flange isentification is
H/N G5247
ADO S/L 09147-2
3"-1/8 API 5K R-35X2-27 MIN BORE
XXS

P/N 142349-01-03-01 REV03 PAK
6A PS TUDD-NL EE-NL PSL1
6A-0553
04/09

 

[MiketheEngineer]

OOPS !! Hate that when that happens...

Uneven heating produced thermal stresses and bingo

 

[blacksmith37]

You are at the thin line between API wellhead (higher strength, LOOSE alloy limits) and ANSI/ASME/ASTM materials. The 1986 (15 ed) of API 6A (some say vintage, some say obsolete) has min yld of 45,000 , C -0.35 max, Mn-1.05 max, Si- 1.35 max. Alloy elements not specified, It may well have alloy because the mfgr does not want to carry inventory (and other wellhead components require alloy to make strength with thickness ).
About all you can do with an existing flange is pre-heat pretty high ,like 400F or more.
The higher rated equipment (10,000/ 20,000 psi) was always a challange to mate to pipeline materials.

 

[stanweld]

Your cracking problem is more than likely due to hydrogen contained in the cellulosic electrodes and lack of appropriate preheat. Either weld with low hydrogen electrodes or preheat to 200F to 250F minimum.

 

[MJCronin]

Can we see pictures of the crack ???

 

[Duwe6]

stanweld is probably correct. Preheat properly: 150 deg F or more at 1.5" thickness [in any direction], use E-7018 from a rod oven or 'fresh' out of an unopened can. Either should correct the cracking problem, by doing both you have about a 99.9% chance of success. If doing the above fails, reject this Heat Number/Lot of flanges -- they are unweldable and fail to meet the metallurgy spec.

ps; did they come from a 3rd-world country????

 

[jamNauman]

yes dear friend u can see the pic but this time i dont have to upload because these was in my colligue cell fone and now he has gone for rotation

dear friends
can any but tell me all these requirement like preheating by the refernce of code and standard and i want to know its chemical composition

regards

Jam Nauman
Moody International

 

[blacksmith37]

Unless API 6A has changed, it has a "flexible" chemistry to permit alloys like 4130 and 8630. You would have to go to your vendor/mill certs for actual composition.

 

[Duwe6]

Additionally, most pipe Codes assume that you know that when you are welding on cast or forged thick fittings, the necessary preheat is much higher than that required for the pipe. Are your welders actually using a WPS? What is the minimum preheat, per that WPS, for the thickness and material group being welded? Do they actually preheat per the WPS?

"Thickness" of flange needs to be measured 'generously', i.e. tape measure thru hub on a slip-on flange; to include the Raised Face and the welding hub height. That's the actual amount of 'cold' steel giving your weld a cooling rate so fast that the weld is ripping itself apart.

 

[stanweld]

As blacksmith37 implied, do find out what the chemistry of the flange is! You may well be forced into using low hydrogen weld processes and higher preheat temperature or possibly scrapping the flange. I have seen such flanges produced from the alloy steels listed above.

Steels may also be mixed. We recently received some AISI 52100 alloy in lieu of carbon steel ordered and as marked from Vietnam. Needless to say, I scrapped the material.

 

[jamNauman]

dear folks

thanks for your attemt to solve the issue

now as asking about wps, we have only a wps for p1 material
and i dont have MTC of these flange
i dont know about the classification of this material
so i want to know about this material either it is covering in P1 material or not
only the identification found on the flange is mentioned on the 1st top section of this page

see on the top

regards

Jam Nauman Anjum

 

[jbeckhou]

IF the 3-1/8" API flange is most likely 4130 45k min. The manufacture of the flange is Ados Pakistan Limited.

http://www.akbarassociates.com.

You have all the information to obtain the MTR's from the flange.
Since you have their API License number, just search thru API's Composite list.

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