Wharf Construction using E71 T-8 wire

By Weld0253 Date 10-31-2008 18:22

Hello,

I am new to this web site. We are currently building a wharf with approximately 50 welders using a 1.8mm E71 T-8 wire. The majority of the welding is joining 16mm thick piles to headstocks. The jetty is approx. 3.5km long and the wharf extension is about 0.5km. All the welders on site have been qualified in the 4G position (single bevel one sided butt) using 16mm plate. The client has called for 100% ultrasonic and Magnetic Particle testing on all butt welds and we are rarely getting failures from this testing. Due to the marine environment and the clients painting specification, the visual welding requirements are quite stringent. We are having to blast and repair the welds up to 4 or 5 times before the final weld visual inspections meet the standard required by our client. I have worked on other large projects using E71-T1 wires and haven't had the level of surface defects I am seeing on this project. Due to the strong coastal breezes, I feel a T-8 wire is the only option we have, unless we use a T-1 and tarp to block the wind?

Can anyone offer some advice on practical solutions to the problems we are experiencing with the T-8 wire. Perhaps we could try a different wire size or there might be other options that I could consider to reduce the amount of re-work, which is costing considerable dollars in re-work.

Thanks in advance

By aevald

Date 10-31-2008 22:45

HelloWeld0253, first off welcome to the forum. A couple of points of clarification for everyone. What diameter of wire are you using? Are there specific job specifications or code requirements that limit you to using the T-8 rated wire? Are there seismic requirements for these weldments? A little more specific description of your limitations, or lack of limitations, might help to illicit more responses. You did mention using the FCAW Gas-shielded wire and then using wind breaks or hooches. That option would certainly provide better aesthetics in most cases and your welders would probably rather run that combination.
The visuals for most of the T-8 wires that I have been around aren't quite as nice as many of the T-11 wires, so if you could use a wire from this classification you may be able to more readily meet the visuals that your customer is seeking. Try to include some more specifics and information and you will likely see other responses to your question. Best regards, aevald

By Weld0253 Date 11-01-2008 15:04

Hi aevald,

Thankyou for taking the time to reply to my questions. The diameter of the wire that we are using is 0.072 in. (1.8mm) E71 T-8 wire. We don't have impact requirements for the wire on this project, however, we do have a H10 requirement on the wire. An E71 T-11 wire wouldn't be an acceptable option to our client.

Earlier in the project, we did attempt to use an E71 T-1 wire, and found that we spent more time grinding the weld out than putting it in. We quite often get ocean breezes around 30 knots which makes wind breaks very difficult.

The majority of welding is in the overhead and vertical positions, doing full penetration single bevel butt welds in 16mm plate. The welding code that we are working to allows certain amounts of welding defects such as undercut and porosity, however, there is another site specification for "marine standard welding requirements for surfaces requiring painting".

When I perform weld inspections on site, the majority of the welds comply with the welding code, however, much of the welding doesn't comply to the marine standard. The marine standard allows no defects such as undercut, surface porosity and requires a smooth toe transition. Initial visual inspection prior to blasting can show extremely small pin holes, however, after blasting these holes become significantly larger and can have some depth. To repair these holes we groove the area no less than 5mm and use a low hydrogen SMAW electrode, and then dress the completed area after welding. After re-blasting more holes can appear. The client inspector will not accept any defects.

In conclusion, what I would like advice on is:

1. Are there any procedural changes I could try and implement to reduce the surface defects we are getting with an E71 T-8 wire?

2. Would it be worth trying a different wire size, or are there any experiences with E71 T-8 wires that result in a good surface finish?

3. Can you successfully use an E71-T1 wire on a project with strong breezes. If so, would it be worth going to the effort to try and block the breezes?

Thanks again in advance.

By aevald

Date 11-01-2008 21:36 Edited 11-01-2008 23:42

Hello again Weld0253, your additional information should certainly make responses from others much more likely. From my own experiences and point of view I would try a few basic things first. I believe the diameter is rather large for the thickness and positional applications that are being done. Many wire manufacturers will have "suggested" positional limitations/suggestions for various diameters of their wires. I believe the vertical application of the .072 is one of those instances where the electrode diameter doesn't match the application. 1/16" wire would be better suited for this and possibly even .052 might be even better. I would suggest this as an example: if you were going to do a vertical fillet weld on 1/2" material theoretically 1/4" E7018, by it's AWS designation could be considered a vertical position rod that could be used. Most individuals would definitely not use the 1/4" in this case,they would probably either use 5/32" or 1/8" electrode instead. To me it comes down to a matter of economics in a sense, the folks who are doing the work will sometimes opt for a process that they feel will provide a higher level of production to accomplish the work more quickly, yet this increase in production can lead to issues of quality. I feel this may be the case here to a certain degree.
   I would make a number of suggestions for you:

1. If they don't want to consider changing electrode diameter, be sure that the wire is fresh and hasn't been subjected to storage where moisture could be absorbed by it. Since you are near to the water where the work is being done this is especially important.

2. Be sure that the welders are using the proper welding parameters for the specific type and diameter of wire and the stick-out is correct, with the .072 diameter they should probably be using between 3/4 and 1" of stick-out. One of the reasons that I am stressing the parameter aspect would have to do with the way that the fluxes react to stick-out and amperage settings. If the stick-out is too short this can prevent proper preheating of the wire and may not activate the fluxes properly which will add to the porosity issues that you might see and a lower amperage setting may contribute in a similar manner.

3. Consider smaller diameter wires if you determine that you are having problems welding within suggested parameters for the .072. By using a smaller diameter wire you may be able to arrive at better aesthetics on your finished weld beads and achieve the visual acceptance described by the code.

4. Also consider trying other manufacturers brands of wires as some are easier to run or run slightly differently, you may find that a different manufacturers brand of wire better suits the welders that you have on the job.

   Please keep us informed on your progress or any breakthroughs that you have, myself and I'm sure others would like to hear about it. In closing here I would definitely take a look at the storage and handling for the wire that is being used, a coastline, or body of water automatically tells me that there is a much higher chance of humidity and moisture contamination of the welding consumables and could certainly have detrimental effects on finished weld beads. Best regards, aevald