dth of welds

By raptor34 (**)

Date 12-15-2011 00:02

I have only ever worked on pipe, but I would have to say it is a procedure issue more than a code issue.

By ozniek

Date 12-15-2011 13:53

Hi fitter

Mostly when this is mentioned in WPS's etc, it is given as the width of "weave". However, if you weave this much, the width of the weld can be substantially wider, or conversely you can get a really wide weld without "weaving" at all. For me a much better measure is the bead width. (As you have mentioned.) The bead width is also correlated with the heat input for SMAW, so also has this added benefit. A bead width of 12mm when welding with a 3mm electrode is not excessive, and this will then be 4X rod diameter.

Is this a code requirement? Indirectly it is, as the wider the weld bead, the higher the heat input, and heat input is an essential or suplementary essential variable, depending on the code. I can not recall having seen an actual limiting value for bead width in any code, but I am certainly open to correction on this point.

Regards
Niekie

By js55

Date 12-16-2011 13:29

ozniek,
Bead width limitations are pretty much where they should be, an engineering decision not a code requirement. Even the Section IX requirements generally only kick in when low temp toughness is at issue. The argument for toughness is valid but it has problems. Quite often wider beads demonstrate better toughness than narrow beads because they may be thinner and subject to greater stress relief and recrystalllization from subsequent beads. Also, not all services are created equal, the argument for heat input control in toughness regimes is predominantly based upon controlling grain size, but this is directly opposed to the mechanical requirements of creep regimes where a larger grain size is beneficial.
Also, the argument for austenitics is perhaps more robust in non toughness applications, typical for austenitics since they, as a general rule, have tremendous low temp toughness, and so the concern shifts to corrosion and segregation etc.
I can only anticipate that any attempt to impose such a requirement by a code committee would soon find itself bogged down in the realities and ambiguities of metallurgy. A simple rule would not survive and the thing would dovetail into a profound revision and subsequently greater confusion.

By welderbrent (*****)

Date 12-16-2011 02:07

Fitter,

Use the 'Search' function above and enter 'Weld Width'. You will find several threads/posts covering this topic. One fairly current. This question comes around quite often in one form or another.

To ask the direct question "Is this code?" would bring a 'NO' from me for MOST cases/codes. And also a 'NO' for "Is it the same for pipe and structural?"

In few cases will you find a direct 'this is how wide the weld is to be' statement within the codes. Even when looked at as some ratio between electrode size and weld width.

Have a Great Day, Brent

By R McLead (**)

Date 12-16-2011 01:05

Below are some examples of typical requirements, some are general suggestions while other are specific and depend on prequalification of WPS.

API STANDARD 1104 Twentieth Edition

7.8 POSITION WELDING

7.8.2 Filler and Finish Beads
The face of the completed weld should be approximately 1/8 in. (3 mm) wider than the width of the original groove.

7.9 ROLL WELDING

7.9.2 Filler and Finish Beads
The face of the completed weld should be approximately 1/8 in. (3 mm) wider than the width of the original groove.

AWS D14.3:2005

7.5.5 Prequalified Procedures for Manual Shielded Metal Arc Welding (SMAW)

7.5.5.5 The maximum thickness of layers subsequent to the root pass of fillet welds and of all layers of groove, welds shall be:
(1) 1/4 in. for root passes of groove welds
(2) 1/8 in. for subsequent layers of welds made in the flat position
(3) 3/16 in. for subsequent layers of welds made in the vertical, overhead, and horizontal positions

7.5.5.6 The maximum size fillet weld which may be made in one pass shall be:
(1) 3/8 in. in the flat position;
(2) 5/16 in. in horizontal or overhead positions;
(3) 1/2 in. in the vertical position.

AWS D1.1:2006

3.7General WPS Requirements

3.7.2 Width/Depth Pass Limitation; Neither the depth nor the maximum width in the cross section of the weld metal deposited in each weld pass shall exceed the width at the surface of the weld pass (see Figure 3.1)

Table 3.7 Prequalified WPS Requirements
Maximum single pass fillet weld size
Flat 3/8 in
Horizontal 5/16 in
Vertical 1/2 in
Overhead 5/16 in

Ray

By raptor34 (**)

Date 12-17-2011 02:50

Ray,

You wouldn't happen to know what the maximum width is for B31.3 would you? I had a weld I came across today that was a 2"x.218"w with a finished cap width of approx. 1.25". It had a 3 bead cap, but was still not something I liked.

By R McLead (**)

Date 12-17-2011 15:51

raptor34,

Unfortunately I do not, I know there are people on the forum that would know.

Ray

By js55

Date 12-19-2011 13:01

"Still not somehting I liked"?
You're kidding right?

By 803056

Date 12-19-2011 16:59

I concur with several of the posts that in general the width of the weld bead is not controlled by the governing code. An exception to the general statement involves one of the ASME construction codes where a welded repair can be performed after PWHT if the width of the weld bead is limited blah, blah, blah.

There have been many "wives tales" over the years about the need to limit the width of a low hydrogen weld deposited with SMAW to 2X, 3X, or 4X the diameter of the electrode. Some of these tales are based on the need to limit heat input for quench and tempered steels or where there is a need to limit heat input to ensure toughness requirements can be met. However, the codes do not limit the width of a weave bead unless heat input must be controlled as in the case where toughness requirements are invoked.

In general, a wide weave results in higher heat input which results in slower cooling. Slower cooling in general results in increased ductility at the expense of hardness and strength if the discussion is limited to carbon and high strength low alloy steels. The same cannot be said of nonferrous alloys. Slow cooling produces larger grain size which enhances creep properties, but smaller grains typical exhibit improved low temperature toughness in comparison if all else is held equal.

I agree with JS' statement, "Still not something I liked? You're kidding right?"

Well stated. If the individual that is assessing the weld is a qualified inspector, he should know that the requirements of the applicable welding standard and the approved welding procedure are the basis of accepting or rejecting a weld. Personal opinion should be reserved for those occasions when an opinion is requested, not for inspection. The acceptance criteria included in the applicable welding standards (or referenced by the welding standard such as is the case with NAVSEA S9074-AR-GIB-010/278) is the basis of accepting or rejecting a weld, not personal likes or dislikes.

Best regards - Al

By js55

Date 12-19-2011 19:07

Always far more eloquent than myself, Al.

By raptor34 (**)

Date 12-20-2011 00:11

I never said I rejected the weld based on how wide it was. I believe that personal opinion does matter, if it didn't matter then why would multiple code say that the welds should be of professional appearance? Wouldn't that mean somebody would have to give a professional opinion on it appearance? If I am wrong correct me. Now issues of "I don't like the way you weave your bead so I am going to make you cut it out" should not happen, but a cap that is nearly 6x wider then the thickness of the part does not constitute a professional appearance to me.

By jon20013 (*****)

Date 12-20-2011 00:29

I've never liked "excessively wide" beads (weaves) it's the way I was trained while studying for my CWI and aso force fed to me on so many nuclear jobs after entering the inspection field.

That said, if one does a search on the topic of pipeline welding, one may eventually find an old Lincoln Electric document that preaches wide beads (weaves). I was lucky enough many years ago to meet one of the old timers who helped write that guide. He didn't convinve me at the time but now that I've learned a bit more I'm not so sure...

I agree with the others, especially js55 and Al.

By JTMcC

Date 12-20-2011 01:40

Line pipe used today is on average quite a bit higher grade material that what was used years ago (same with operating pressures , 2000psi is the new 1500psi)and I think you'll find it pretty normal for gas companies to require the cap be split into multiple beads at .500 wall.
Some go to two bead cap at .500 wall, some go to three bead. Some go to two bead at .500W and three bead at .600W.
They also will put meters on your machine check amps & volts from time to time, then mark off a foot of weld and time your progression speed.
The old timers remember when they puddle capped .650W, but those days are gone.
In transmission work the gas company always has requirements above and beyond the code.

So you have to take an "old" Lincoln Electric document as maybe interesting and historical but not a reflection of the materials, consumables or procedures in use today.

JTMcC

By 803056

Date 12-20-2011 04:37 Edited 12-20-2011 05:01

I have no problem with controlling the width of a weld bead as long as it not based on unfounded personal opinion or "because it is required by code".

There are reasons to control bead width with certain materials or for certain service applications, but anytime restrictions are place on welding technique there are costs associated with those restrictions.

My experience has been that when restrictions are put in place, it is usually not based on metallurgical considerations, but on personal opinion based on "how we did it on my last job" mentality. The mentality; "I can make as wide a weave as I want, because that's the way I've always dun it" is just as bad as "no weave more than 3X the diameter of the rod" when neither is based on sound metallurgical principles.

Restrictions imposed on the welder that ensure consistent results from one welder to the next, that is to say ensures the mechanical properties are met consistently are reasonable and justifiable. Unnecessary restrictions imposed because "that's the way I want it" are often wasteful and detrimental to producing welds with the required properties.

Raptor; I don't want to cast dispersions your way, but that is one of the points I was trying to make. The inspector's personal opinion should be held in reserve. Acceptance criteria included in most welding standards is not based on the opinion of one person, but a group of people that have extensive experience that usually have test data to substantiate their position. The welding standard sets the ground rules, the inspector simple determines if the rules are met or they are not met. The inspector, working in isolation, is not the individual that formulates the rules. Few codes include terminology such as "first class workmanship", "in a professional manner", or "professional appearance". Those criteria are subjective rather than objective. They provide no means of applying metrics to the welds being evaluated. Instead, most welding standards are prescriptive define the empirical acceptance criteria, i.e., undercut is limited to 1/16 inch depth, overlap is prohibited, face reinforcement is limited to 3/32 inch, etc., so any accept/reject decision is objective rather than subjective. Any two or three inspectors should be able to examine the same weld and come to the same conclusion based on objective criteria. When subjective criteria are the basis of inspection, no two inspectors will judge the weld the same.

Best regards - Al