J-Groove Or Fillet Weld Type

[TorsionalStress]

The application consists of capping both ends of a pipe with plates, by means of preparing the edges. The welding will be done by the outside circumferential joints. The drawing indicates a J-groove weld type which requires more work. Can a beveled fillet weld instead of a J-groove weld be performed on these joints? If not, what is the rule of thumb for weld size for J-groove welds?

Any response will be greatly appreciated!

 

[racookpe1978]

True, your concern about the J prep shape being more expensive than a simple bevel prep - NOT a "fillet" is likely correct.

So, change the drawing. (That is, justify to your boss and the person who has to change the drawing, and that person's boss that his/her time spent changing the drawing is less expensive than the time to make a J-shape at the end of the pipe by the workers.)

But, until the drawing is changed to a bevel prep by a cognizant engineer by a formal change process, you have no choice but to follow the drawing.

 

[TorsionalStress]

I personally think a fillet weld is more than enough, it’s a simple bracket. The only issue is that it’s going in a nuclear environment which has no bearing on the weld type.

 

[SnTMan]

Nuclear? You will be money ahead by far to make the J-groove weld rather than get a drawing change, I'll bet.

Regards,

Mike

 

[vanci]

Depending on design, J grooves typically require less filler metal. When determining joint prep several factors are taken in to account; such as wall thickness, welding process and whether it is manual or machine, quality inspection requirements, and what the design/ weld engineer personally prefers. Since it is a nuclear application, an additional factor is where the "simple bracket" will be installed, i.e. how close to the reactor and what equipment does it support? Is it a full penetration weld? All things considered, I agree with SnTMan, just weld the J groove.

 

[Duwe6]

1 - The J-groove callout means that only a full-penn weld is acceptable.

2 - vanci is pretty much right, except than ANY full-penn weld will fuful the design requirements.

3 - SnTMan has hit the *essential* point. Getting a Change Order run through for Nuke work takes months, if they like you and if they consider your proposed change worthwhile. Thus, the odds of getting a Change Order before Halloween are somewhat between slim, and none [and Slim has left town].

Just build it like it was drawn, and be a little more detail-oriented the next time you bid on Nuke work. Nuke stuff has to be essentially perfect, for them to consider that work as 'marginally acceptable'. Not kidding on this one. I strated out building nuke plants in the USA in 1981. We scrapped a BUNCH of 'good' work, and had it remade until it was essentially perfect. Those aren't really nuke plants you are looking at, those are the world's biggest Swiss watches.

 

[TorsionalStress]

What is the rule of thumb for weld size regarding J-groove welds?

 

[Duwe6]

"Full-Penetration", meaning "Fill it Up"

A small-to-zero root protrusion "root reinforcement", and a small cap protrusion "cap reinforcement".

 

[Guest102023]

We should start out by knowing the pipe diameter - ¾ or 36 inch?

 

[TorsionalStress]

3 pipe sizes;
• Nominal pipe 8, OD 8.62 x .32 wall
• Nominal pipe 14, OD 14 x .59 wall
• Nominal pipe 16, OD 16 x .66 wall

 

[wannabeSE]

Modern Steel recently had an article discussing the economy of welds.

http://www.modernsteel.com/Uploads/Issues/July_2011/072011_July11_Welding_web.pdf

 

[TorsionalStress]

The article basically states common sense approach as I’ve stated in my question, J-Groove or Fillet Weld Type? Unfortunately, the article did not mention minimum weld size requirement for J-Groove welds which is what I was hoping for.

 

[racookpe1978]

No.

The requirements for the final "shape" of the J-prepped weld have been presented above: The "groove" must be fully filled up ABOVE the surface of the original pipe wall. The final weld contour must be "positive" (higher than the original OD of the pipe), with a nominal maximum height limited by YOUR COMPANY's weld procedure. Usually, this maximum reinforcement height is 1/8 inch, but you have not presented your company's WPS for review to confirm this.

By the way, expect the power plant's nuclear weld inspectors to require a copy of this WPS procedure, your welder's qualifications, your welder training requirements and re-cert papers, the weld material and weld filler cert's, and your company's QA inspections of the intermediate pass and final weld NDE inspections.

As stated above, if you want to want to change the weld design to something else for this nuclear application, change the drawing. If you don't want to pay for changing the drawing, follow the drawing - and be able to prove to the power plant that you followed all parts of the drawing.

True, true. It is not a pressure boundary of a piece of radiactive-containing high-pressure pipe in a safety system. I don't care, the plant will not care. it is being installed under their approval inside their plant in accordance with their approved drawing.

You are apparently providing a support inside a nuclear plant (which will be stressed under earthquake or accident conditions and under operational cycles and pressures and strains); and we who will be working underneath your support and who will be providing equipment and piping and machinery installed underneath your support really, really, really really want your support to be built in accordance with the plans you were provided.

 

[TorsionalStress]

racookpe1978, I understand what you are saying; this is the reason why I posted this question, because I have concerns since I’m the one designing the fixtures. The welding will be done by an automated robot. Someone will be responsible to ensure that the welds conform to specification. The engineer who designed the brackets is telling me that it’s just a bracket, so you (meaning me) can make the weld anything you want. He’s indicated on the drawing a 0.14” J-groove weld at a 30? for a pipe thickness of .32” and a ½” thick plate. This obviously is not a full penetrated weld. I think you can now understand my concern. If the procedure is a full penetrated weld, does this mean a “Root face thickness” of zero or a minimum value i.e. (1/16”)?

 

[vanci]

What welding process are you going to use? As for the dimensions you listed, is the 0.14" the depth of the joint or a radius?

 

[TorsionalStress]

I’m not involved in the welding process at all. The 0.14” is the joint depth.

 

[Duwe6]

If the "depth of prep" is 0.14", then the requirement is that your weld fill the joint, with a slight 'cap' - external reinforcement. Since the depth-of-prep is limited, then there is no expectation of full-pennetration. Just fill up the J-groove.

 

[TorsionalStress]

Using the .322” pipe & the .5” plate, what joint depth, joint total angle & joint radius would you suggest if you had the choice?

 

[SnTMan]

What you need to do is get the engineer to fully specify the weld(s). That's his job.

Regards,

 

[vanci]

SnTMan is correct, the engineer should specify what he requires. When you ask him to specify the exact joint dimensions, that would also be a good time to ask about the single bevel instead of the J. Perhaps if this job comes around again it will be a bevel.