Back purge setup

Attached Files 'Y' at flowmeter. For a really inexpensive and simple option, try Solarflux or Superior No. No back purge necessary. I use Superior No. Can someone tell me what the purpose of the purge is? Is this only for TIG? I never purge C25 on my mig welder. Thanks in advance. SS is extreamly suseptable to air contamination so you need to protect the back side of the weld or it will become contaminated. SS is the only place i see MIG needing a back purge and that would depend on the thickness and settings.

Can't find a catlog in the mess on my desk, but check out www. Originally posted by phila. We just opened the torch side all the way, set the flow and then opened up the back gas. Drew Guldalian Engin Cycles www. Re: Back Purge Setup I saw someone else do this but i used air compressor fittings work really well as quick-connects and also shut off the flow when disconnected.

One line goes to the fixture and one goes to the BB heatsink when i'm welding in the Park stand. I've purchased the parts-list zank cooked up in this MTBR forum: Two tanks or dual out put flow meter for back purging? It looks like Tyler Firefly only purges the joint he's working on: I believe quite a few of you hook all of the heatsinks up and fill the entire bike up.

Any downsides to purging one joint at a time? Thanks, James PJ Nelson. Re: Back Purge Setup There are things to consider here about purging and your goals.

Steel purging is very simple as you are not really doing anything other than a basic step to help prevent hardened penetration on the inside of the weld. It takes almost no argon to achieve this and having oxygen present along with the argon is still fine.

Titanium is another story and you need to be very concerned with the argon presence and turbulence. I look at each joint as having three points of entry. I tend to run argon in two of the ports the lower two and allow the third port to exhaust the dirty air.

The chain stays and seat stays are much trickier since your argon is entering the tube from the seat tube or the BB and you are trying to allow for exhaust from the same tube you are filling with argon. The breather hole needs to be large enough to prevent pressure build up inside the tube. You would never want to have all the points of entry getting argon. How does the dirty air escape if you pump stuff in from all points of entry? Not sure if that helps or answers your question.

Similar Threads Any back experts here? Lower back pain issues By Saab in forum General Discussion. Replies: 43 Last Post: , PM. Back to Back Days -- Block head training? By Watoni in forum General Discussion. Replies: 3 Last Post: , PM. Replies: 14 Last Post: , PM. Bookmarks Bookmarks Google Facebook. All times are GMT The time now is AM. All rights reserved. Whatever type of block you use to create a seal for your back purging, you need to have some sort of some sort of vent for the atmospheric gas to escape.

Venting is important. They will try to escape through the only opening, which will be the weld you are working on and possibly cause an explosion. Make several small tack welds spaced along the diameter of the object to keep things in place while you do the final root pass weld. Be careful not to add too many tack welds as they can cause weld decay before you even start.

The gas chamber needs to be filled with argon before you start your weld. Be patient. Turn on the gas regulator and wait about 30 seconds for the chamber to fill completely with the argon.

Remember argon is a heavy gas and will fill from the bottom up. If you are using helium, a lighter gas, it will flow in from the top.

Use your flow meter to ensure you have the right levels. When the gas has completely filled the chamber, the inside of the tube should be shielded and ready for you to start welding and back purging. Stainless steels, and alloys with titanium, nickel and zirconium when heated to high levels, react to water, grease, and gases floating free in the environment among other things.

This reaction causes the filler used in the weld to mix with the contaminant and oxidize or sugar. This contaminated weld creates an ugly, weak surface affecting the integrity of the weld. TIG welding provides a constant shield when welding from the top side. The TIG method works fine for the outside of the weld.

Not only does it create a stronger weld, it looks good too, but only on the outside; the side you see. To get a stronger, more dependable weld that is just as smooth on the inside as on the outside, you need to produce that same shielding environment on the inside as you do on the outside.

Back purging shields the underside of the weld from the elements in the surrounding atmosphere. This gives the root weld a stronger seam and a smoother surface on both sides. With back purging, that same even finish that is visible on the outside is created on the inside of the seam.

This makes for a better weld that results in better flow rates and virtually no chance of contamination. For some people, out of sight, is out of mind. Sometimes using gas for back purging may not be the best or most cost effective choice. Neither of these are good reasons to not back purge. There are several alternatives to using argon gas for back purging. A few options are listed below. Which method you use depends on how your project will be used.

As with any project, you should make sure the final product is thoroughly cleaned and any residue removed. The shielding flow of an inert gas be it argon, helium, or nitrogen, in TIG welding protects the surface root weld, but leaves the underneath surface exposed.

This is easy to fix in flat surfaces. Hollow objects such as tubes and pipes are vulnerable to oxidation on the hidden underside. Without back purging, the weld looks great from the outside, but will ultimately fail. If you are unsure of which metals need back purging, you should always refer to a WPS Welding Procedure Specification for coding specs and guidance.