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Weldolet Questions
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(Mechanical)
(OP)
7 Oct 15 22:16Hello All,
When welding a smaller weldolet (WOL) fitting to a larger run pipe for a branch connection, would the weld to the run pipe/header be considered a buttweld or fillet weld? What is the standard bevel angle for the WOL fitting on the side that welds to the run pipe? I can't seem to find this dimensional info from Bonney Forge, MSS SP97, or any other source.
I'm trying to determine whether or not a WOL (i.e. integrally reinforced outlet fitting) is considered to attach to the run pipe/header as a fillet weld as described in ASME B31.4, 404.3.4(b). If so, this would mean the WOL needs to be beveled down to the same thickness as the run pipe/header in many cases.
Thanks
(Mechanical)
8 Oct 15 01:48 Krausen-I'd suggest you read page 35 (right hand side of page 19 of the pdf) of the catalog: http://www.bonneyforge.com/resources/BC.pdf Note that the weld as shown in both the longitudinal and transverse sections is a full pen groove weld.
(Mechanical)
(OP)
8 Oct 15 03:55jte - excellent, thank you for this link. Not having much background in welding, I assume this full pen groove weld is NOT a type of fillet weld.
I've had more experienced coworkers mention the idea of using re-pads underneath larger, heavier wall WOL welds to run pipe (e.g. a 4" XS WOL welded to 20" 0.500" w.t. run pipe). They mentioned something about "buttering" the run pipe at the WOL weld location. They said this was done to dissipate heat and protect the run pipe from warping/heat damage. I'm not sure I follow. I don't see anywhere in the pressure piping codes where this is required. It appears that if any WOL is installed properly with a single full pen groove weld than you're set, regardless of WOL schedule or run pipe wall thickness. Would you agree?
Thanks
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(Petroleum)
8 Oct 15 09:24When using integrally re-inforced fittings you should have no need for a re - pad - this is built into the fitting.Buttering I had heard about and had to go look up, but essentially it is used either for welding dissimilar metals or for when you've cut too large a hole. It could be used in this instance to pre-weld the re-inforcing passes, but seems a bit extreme.You probably won't find things in the codes because this is about practical construction issues.normally bending is only really an issue if you have fittings close to the run size of the pipe and thick ones. A 4" on a 20" shouldn't be an issue to me.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
(Petroleum)
8 Oct 15 09:52Buttering along with temper bead techniques are routinely used in Canada, and to a lesser extent in the U.S. It adds some structural support, lowers the potential for underbead cracking, and depth of Heat Affected Zone. We use it almost daily with great success. The September 2014 Welding Journal has an article that describes the method along with the results of an experiment demonstrating its effectiveness to significantly decrease hardness.
(Mechanical)
(OP)
8 Oct 15 12:02Littleinch - not needing any additional reinforcement (re-pad, saddle, etc.) for WOL connections to run pipe/headers was my understanding as well.
SectionIX - I will try to get ahold of the Sep 14 Welding Journal you mention. Would you provide any more details on this buttering proces as it applies to a WOL? Say for a 10" XS WOL to be welded to a 26" 0.500" w.t. run pipe (I'm actually needing to evaluate this case proposed by a client) ... Would buttering the run pipe in this case entail laying down a number of circular beads around the hole cut out for the 10" WOL connection?
Thanks
(Industrial)
8 Oct 15 13:39 http://www.absa.ca/wp-content/uploads/2015/04/2008...(Petroleum)
9 Oct 15 12:49Krausen
This method is generally applied to In-Service welding where the technique provides the greatest benefit.
(Short version:) UT target location; avoid areas with corrosion loss, lamination, etc. Low hydrogen electrode stringer beads are tightly placed around and beyond the periphery of the area where the olet is to be attached. Starts and stops are staggered by at least an inch or so. This first pass is ground to a height ~ 3mm. Next [temper] pass is placed directly over previous pass. Repeat: Number of passes depends on OD/thickness/material grade/etc. MT final pass with a wet method.
As previously mentioned, this is a technique generally applied to in-service welding for which you will need to have qualified welders and welding procedures. API 1104 Appendix B and ASME Section IX QW-283 provide guidance. Appendix B of the 21st edition of API 1104, published but not yet adopted by PHMSA is a better resource than the current 20th edition.
I strongly recommend against you using this method until you gain suitable experience and knowledge as the method, because, if improperly performed, can result in a deleterious weld. I cannot stress this enough.
(Mechanical)
10 Oct 15 02:12back to the original question
When welding a smaller weldolet (WOL) fitting to a larger run pipe for a branch connection, would the weld to the run pipe/header be considered a buttweld or fillet weld?
the bonneyforge document says its a full penetration groove weld but B31.3, 328.5.4 welded branch connections says its a full penetration V-groove finished with a cover fillet weld.
(Petroleum)
10 Oct 15 12:34I thinks, Weld to the rung pipe/header is groove weld or branch weld, it was not butt or fillet
(Petroleum)
12 Oct 15 09:39It's a combination groove an fillet.
(Structural)
12 Oct 15 17:24Weld-o-let, thread-o-lot, etc. are brand names. You will not find them referenced by the construction codes. However, if one looks for an "integrally reinforced branch fitting" you should see that they are a completely joint penetration groove weld with a reinforcing fillet around the outside circumference. The size of the reinforcing fillet is dependent on the specific construction code and is based on the thickness of the branch pipe.Typically the IRB fitting is manufactured to fit a couple of pipe sizes. The welder is expected to hand fit and grind the fitting to sit on the run pipe with the proper root opening and root face around the fitting. If the welders can, they will set the fitting on the run pipe and ignore the need for hand fitting it. Tricky little devils, these welders.
Best regards - Al
(Mechanical)
14 Oct 15 15:18It's been my experience that typically o-let manufacturers provide a "weld line" on the fittings, especially the larger ones, which is usually the first transition point in the bevel of the fitting. When installing the fitting the welder fits and tacks the o-let into place on the run pipe and then fills out the groove to the "weld line" at a minimum. The cover fillet weld is then deposited after the groove weld is completed.
If no weld line is indicated on the fitting the best practice is to make sure that the thickness of the completed groove weld is at least as thick as the branch wall that will be attaching to the fitting, again finished with the required cover fillet weld.
numberfive
(Mechanical)
(OP)
14 Oct 15 20:37Thank you all for your responses. This has been very helpful. I'd still like to understand the welding term "buttering" a bit more, but I will continue to research this.
gtaw - Not sure what you meant by the welder having to "grind the fitting to sit on the run pipe ..." The weld ends should be beveled on both the branch groove weld side and other buttweld side. As you mentioned, o-lets are also forged to different contours (or no contour) on the branch side in order to fit different run size ranges. Where would the grinding come into play?
(Materials)
14 Oct 15 21:52I have nothing intelligent to offer about weldolets, but buttering is just laying down a bead that's not intended to fuse a joint. It's pretty typical for dissimilar metal welds where welding directly would result in an undesirable microstructure (martensite), so a different alloy is laid down first so that no undesirable microstructures are formed in the weld bead with yet a different filler. Spend some time staring at a Schaeffler Diagram if that doesn't make sense.It's like putting peanut butter on toast before the jelly because if you don't it just makes a soggy disappointing sandwich...You do see it occasionally applied in situations where someone is concerned about heat input (warping or burnthrough), so they'll lay down a bead with a lower heat input than the actual weld first.
www.linkedin.com/pub/nathan-brink/35/861/18
(Petroleum)
14 Oct 15 23:47krausen,
The optimum root gap is one that is equal all around.
O'lets are supplied for a range of pipe sizes - they will only fit perfectly on one actual run pipe diameter.
The other diameters will require grinding to shape the fitting to the run pipe.
As Al mentioned some welders get lazy and just pop them on and weld - maybe 2 mm root gap in places and 4 mm in others.
No problem if they obtain 100% root fusion but they increase the chance of root defects by starting off with a poorly fitted up weld joint.
Hope that makes sense,
Cheers,
DD
(Structural)
15 Oct 15 03:54DekDee; I couldn't have said it better or I would have! Well put my friend.
Best regards - Al
(Mechanical)
(OP)
15 Oct 15 12:35DekDee & gtaw - Interesting ... So for example, would that mean a 2" WOL made for a run size range between 8" - 24" will only properly fit the 8" run pipe without grinding? I never knew this but will consider adding a note to our drawings since we've been dealing with some branch connection welds that have failed (started slowly weeping) after a few years in service.
Thanks
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